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Introducing ASP.NET Web Pages 2 |
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Mike Pope |
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Summary: This set of tutorials gives you an overview of ASP.NET Web Pages |
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(version 2) and Razor syntax, a lightweight framework for creating dynamic |
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websites. It also introduces WebMatrix, a tool for creating pages and sites. The |
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tutorials take you from novice programmer through seeing your site live on the |
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Internet. Topics include how to install Microsoft WebMatrix (a set of tools for |
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creating sites); how to work with forms; how to display, add, update, and delete |
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data; how to create a consistent site layout; and how to publish to the Web. |
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Category: Step-by-Step |
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Applies to: ASP.NET Web Pages 2 RC, Visual Studio 2012 RC |
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Source: ASP.NET site (link to source content) |
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E-book publication date: June 2012 |
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Copyright © 2012 by Microsoft Corporation |
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All rights reserved. No part of the contents of this book may be reproduced or transmitted in any form or by any |
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means without the written permission of the publisher. |
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Microsoft and the trademarks listed at |
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http://www.microsoft.com/about/legal/en/us/IntellectualProperty/Trademarks/EN-US.aspx are trademarks of the |
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Microsoft group of companies. All other marks are property of their respective owners. |
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The example companies, organizations, products, domain names, email addresses, logos, people, places, and |
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events depicted herein are fictitious. No association with any real company, organization, product, domain name, |
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email address, logo, person, place, or event is intended or should be inferred. |
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This book expresses the author’s views and opinions. The information contained in this book is provided without |
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any express, statutory, or implied warranties. Neither the authors, Microsoft Corporation, nor its resellers, or |
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distributors will be held liable for any damages caused or alleged to be caused either directly or indirectly by this |
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book. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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2 |
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Contents |
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Tutorial 1: Getting Started ............................................................................................................. 4 |
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Tutorial 2: Programming Basics ................................................................................................... 19 |
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Tutorial 3: Displaying Data ........................................................................................................... 39 |
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Tutorial 4: HTML Form Basics ...................................................................................................... 56 |
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Tutorial 5: Entering Database Data by Using Forms ...................................................................... 70 |
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Tutorial 6: Updating Database Data ............................................................................................. 82 |
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Tutorial 7: Deleting Database Data .............................................................................................. 97 |
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Tutorial 8: Creating a Consistent Layout .................................................................................... 104 |
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Tutorial 9: Publishing a Site by Using WebMatrix ....................................................................... 118 |
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Appendix: Code Listings ............................................................................................................. 127 |
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This set of tutorials gives you an overview of ASP.NET Web Pages (version 2) and Razor syntax, a |
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lightweight framework for creating dynamic websites. It also introduces WebMatrix, a tool for |
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creating pages and sites. |
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Level: New to ASP.NET Web Pages. |
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Skills assumed: HTML, basic cascading style sheets (CSS). |
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Prerequisites: Windows XP SP3 or later. (See What Do You Need? later for more details.) |
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Downloads: Completed website for the ASP.NET Web Pages introductory tutorial |
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Note This tutorial is based on the ASP.NET Web Pages version 2 RC and Microsoft |
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WebMatrix 2 RC. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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3 |
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Tutorial 1: Getting Started |
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What you'll learn in the first tutorial of the set: |
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• What ASP.NET Web Pages technology is and what it's for. |
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• What WebMatrix is. |
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• How to install everything. |
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• How to create a website by using WebMatrix. |
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Features/technologies discussed: |
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• Microsoft Web Platform Installer. |
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• WebMatrix. |
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• |
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.cshtml pages |
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What Should You Know? |
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We're assuming that you're familiar with: |
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• HTML. No in-depth expertise is required. We won't explain HTML, but we also don't use |
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anything complex. We'll provide links to HTML tutorials where we think they're useful. |
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• Cascading style sheets (CSS). Same as with HTML. |
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• Basic database ideas. If you've used a spreadsheet for data and sorted and filtered the |
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data, that's the level of expertise we're generally assuming for this tutorial set. |
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We're also assuming that you're interested in learning basic programming. ASP.NET Web Pages |
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use a programming language called C#. You don't have to have any background in programming, |
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just an interest in it. If you've ever written any JavaScript in a web page before, you've got plenty |
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of background. |
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Note that if you are familiar with programming, you might find that this tutorial set initially moves |
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slowly while we bring new programmers up to speed. As we get past the first few tutorials, |
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though, there will be less basic programming to explain and things will move along at a faster clip. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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4 |
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What Do You Need? |
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Here's what you'll need: |
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• A computer that is running Windows 7, Windows Vista SP2, Windows XP SP3, Windows |
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Server 2003 SP2, Windows Server 2008, or Windows Server 2008 R2. |
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• A live internet connection. |
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• Administrator privileges (required for the installation process). |
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What Is ASP.NET Web Pages? |
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ASP.NET Web Pages is a framework that you can use to create dynamic web pages. A simple |
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HTML web page is static; its content is determined by the fixed HTML markup that's in the page. |
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Dynamic pages like those you create with ASP.NET Web Pages let you create the page content on |
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the fly, by using code. |
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Dynamic pages let you do all sorts of things. You can ask a user for input by using a form and then |
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change what the page displays or how it looks. You can take information from a user, save it in a |
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database, and then list it later. You can send email from your site. You can interact with other |
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services on the web (for example, a mapping service) and produce pages that integrate |
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information from those sources. |
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What Is WebMatrix? |
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WebMatrix is a tool that integrates a web page editor, a database utility, a web server for testing |
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pages, and features for publishing your website to the Internet. WebMatrix is free, and it's easy to |
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install and easy to use. (It also works for just plain HTML pages, as well as for other technologies |
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like PHP.) |
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You don't actually have to use WebMatrix to work with ASP.NET Web Pages. You can create pages |
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by using a text editor, for example, and test pages by using a web server that you have access to. |
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However, WebMatrix makes it all very easy, so these tutorials will use WebMatrix throughout. |
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About These Tutorials |
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This tutorial set is an introduction to how to use ASP.NET Web Pages. There are 9 tutorials total in |
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this introductory tutorial set. It's part of a series of tutorial sets that takes you from ASP.NET Web |
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Pages novice to creating real, professional-looking websites. |
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This first tutorial set concentrates on showing you the basics of how to work with ASP.NET Web |
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Pages. When you're done, you can work with additional tutorial sets that pick up where this one |
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ends and that explore Web Pages in more depth. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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5 |
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We deliberately go easy on the in-depth explanations. And whenever we show something, for this |
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tutorial set we always chose the way that we think is easiest to understand. Later tutorial sets go |
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into more depth and show you more efficient or more flexible approaches (also more fun). But |
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those tutorials require you to understand the basics first. |
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The tutorial set you've just started covers these features of ASP.NET Web Pages: |
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Introduction and getting everything installed. (That's in the tutorial you're reading.) |
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• |
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• The basics of ASP.NET Web Pages programming. |
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• Creating a database. |
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• Creating and processing a user input form. |
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• Adding, updating, and deleting data in the database. |
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At any point you can publish (deploy) your site to a hosting provider. We'll talk about that at the |
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end of this tutorial set and link you to a tutorial on how to do that. |
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What Will You Create? |
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This tutorial set and subsequent ones revolve around a website where you can list movies that |
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you like. You'll be able to enter movies, edit them, and list them. Here are a couple of the pages |
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you'll create in this tutorial set. The first one shows the movie listing page that you'll create: |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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6 |
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And here's the page that lets you add new movie information to your site: |
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Subsequent tutorial sets build on this set and add more functionality, like uploading pictures, |
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letting people log in, sending email, and integrating with social media. |
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Ok, let's get started. |
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Note You can download a finished version of the website that's described in these |
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tutorials. |
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Installing Everything |
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You can install everything by using the Web Platform Installer from Microsoft. In effect, you install |
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the installer, and then use it to install everything else. |
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To use Web Pages, you have to be have at least Windows XP with SP3 installed, or Windows |
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Server 2008 or later. |
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On the Web Pages page of the ASP.NET website, click Install WebMatrix. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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7 |
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This button takes you to the Web Platform Installer page on the Microsoft.com site. |
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If the download doesn't start automatically, click the Install Now button. Then click Run. (If you |
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want to save the installer, click Save and then run the installer from the folder where you saved |
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it.) |
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The Web Platform Installer appears, ready to install WebMatrix. Click Install. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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8 |
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The installation process figures out what it has to install on your computer and starts the process. |
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Depending on what exactly has to be installed, the process can take anywhere from a few |
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moments to several minutes. |
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Hello, WebMatrix |
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When it's done, the installation process can launch WebMatrix automatically. If it doesn't, in |
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Windows, from the Start menu, launch Microsoft WebMatrix. |
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In Windows, start Microsoft WebMatrix. |
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To begin, you'll create a blank website and add a page. In the next tutorial set, you'll use one of |
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the built-in website templates. |
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In the start window, click Templates. Templates are prebuilt files and pages for different types of |
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websites. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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9 |
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In the Quick Start window, select Empty Site and name the new site "WebPagesMovies". |
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Click Next. |
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WebMatrix creates and opens the site: |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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10 |
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At the top, there's a Quick Access Toolbar and a ribbon, like in Microsoft Office 2010. At the |
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bottom left, you see the workspace selector where you switch between tasks (Site, Files, |
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Databases, Reports). On the right is the content pane for the editor and for reports. And across |
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the bottom you'll occasionally see a notification bar for messages. |
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You'll learn more about WebMatrix and its features as you go through these tutorials. |
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Creating a Web Page |
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To become familiar with WebMatrix and ASP.NET Web Pages, you'll create a simple page. |
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In the workspace selector, select the Files workspace. This workspace lets you work with files and |
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folders. The left pane shows the file structure of your site. The ribbon changes to show file-related |
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tasks. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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11 |
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In the ribbon, click the arrow under New and then click New File. |
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WebMatrix displays a list of file types. Select CSHTML, and in the Name box, type "HelloWorld". A |
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CSHTML page is an ASP.NET Web Pages page. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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12 |
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Click OK. |
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WebMatrix creates the page and opens it in the editor. |
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As you can see, the page contains mostly ordinary HTML markup, except for a block at the top |
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that looks like this: |
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@{ |
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} |
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That's for adding code, as you'll see shortly. |
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Notice that the different parts of the page — the element names, attributes, and text, plus the |
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block at the top — are all in different colors. This is called syntax highlighting, and it makes it |
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easier to keep everything clear. It's one of the features that makes it easy to work with web pages |
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in WebMatrix. |
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Add content for the <head> and <body> elements like in the following example. (If you want, you |
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can just copy the following block and replace the entire existing page with this code.) |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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13 |
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@{ |
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} |
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<!DOCTYPE html> |
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<html lang="en"> |
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<head> |
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<meta charset="utf-8" /> |
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<title>Hello World Page</title> |
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</head> |
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<body> |
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<h1>Hello World Page</h1> |
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<p>Hello World!</p> |
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</body> |
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</html> |
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In the Quick Access Toolbar or in the File menu, click Save. |
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Testing the Page |
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In the Files workspace, right-click the HelloWorld.cshtml page and then click Launch in browser. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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14 |
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WebMatrix starts a built-in web server (IIS Express) that you can use to test pages on your |
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computer. (Without IIS Express in WebMatrix, you'd have to publish your page to a web server |
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somewhere before you could test it.) The page is displayed in your default browser. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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15 |
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localhost and port numbers |
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Notice that when you test a page in WebMatrix, the URL in the browser is something like |
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http://localhost:33651/HelloWorld.cshtml. The name localhost refers to a local server, meaning |
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that the page is served by a web server that's on your own computer. As noted, WebMatrix |
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includes a web server program named IIS Express that runs when you launch a page. |
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The number after localhost (for example, localhost:33651) refers to a port number on your |
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computer. This is the number of the "channel" that IIS Express uses for this particular website. |
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The port number is selected at random from the range 1024 through 65536 when you create your |
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site, and it's different for every site that you create. (When you test your own site, the port |
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number will almost certainly be a different number than 33561.) By using a different port for each |
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website, IIS Express can keep straight which of your sites it's talking to. |
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Later when you publish your site to a public web server, you no longer see localhost in the URL. At |
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that point, you'll see a more typical URL like http://myhostingsite/mywebsite/HelloWorld.cshtml |
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or whatever the page is. You'll learn more about publishing a site later in this tutorial series. |
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Adding Some Server-Side Code |
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Close the browser and go back to the page in WebMatrix. |
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Add a line to the code block so that it looks like the following code: |
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@{ |
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var currentDateTime = DateTime.Now; |
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} |
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This is a little bit of Razor code. It's probably clear that it gets the current date and time and puts |
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that value into a variable named currentDateTime. You'll read more about Razor syntax in the next |
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tutorial. |
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In the body of the page, after the <p>Hello World!</p> element, add the following: |
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<p>Right now it's @currentDateTime</p> |
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This code gets the value that you put into the currentDateTime variable at the top and inserts it |
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into the markup of the page. The @ character marks the ASP.NET Web Pages code in the page. |
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Run the page again (WebMatrix saves the changes for you before it runs the page). This time you |
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see the date and time in the page. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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16 |
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Wait a few moments and then refresh the page in the browser. The date and time display is |
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updated. |
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In the browser, look at the page source. It looks like the following markup: |
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<!DOCTYPE html> |
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<html lang="en"> |
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<head> |
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<meta charset="utf-8" /> |
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<title>Hello World Page</title> |
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</head> |
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<body> |
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<h1>Hello World Page</h1> |
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<p>Hello World!</p> |
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<p>Right now it's 1/18/2012 2:49:50 PM</p> |
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</body> |
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</html> |
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Notice that the @{ } block at the top isn't there. Also notice that the date and time display shows |
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an actual string of characters (1/18/2012 2:49:50 PM or whatever), not @currentDateTime like you |
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had in the .cshtml page. What happened here is that when you ran the page, ASP.NET processed |
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all the code (very little in this case) that was marked with @. The code produces output, and that |
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output was inserted into the page. |
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This Is What ASP.NET Web Pages Are About |
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When you read that ASP.NET Web Pages produces dynamic web content, what you've seen here |
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is the idea. The page you just created contains the same HTML markup that you've seen before. It |
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can also contain code that can perform all sorts of tasks. In this example, it did the trivial task of |
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getting the current date and time. As you saw, you can intersperse code with the HTML to |
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produce output in the page. When someone requests a .cshtml page in the browser, ASP.NET |
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processes the page while it's still in the hands of the web server. ASP.NET inserts the output of the |
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code (if any) into the page as HTML. When the code processing is done, ASP.NET sends the |
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resulting page to the browser. All the browser ever gets is HTML. Here's a diagram: |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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17 |
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The idea is simple, but there are many interesting tasks that the code can perform, and there are |
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many interesting ways in which you can dynamically add HTML content to the page. And ASP.NET |
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.cshtml pages, like any HTML page, can also include code that runs in the browser itself (JavaScript |
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and jQuery code). You'll explore all of these things in this tutorial set and in subsequent ones. |
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Coming Up Next |
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In the next tutorial in this series, you explore ASP.NET Web Pages programming a little more. |
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Additional Resources |
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• HTML Tutorial on the W3Schools site. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 1: Getting Started |
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18 |
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Tutorial 2: Programming Basics |
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This tutorial gives you an overview of how to program in ASP.NET Web Pages with Razor syntax. |
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What you'll learn: |
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Some basic C#, which is the programming language you'll use. |
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Some fundamental programming concepts for Web Pages. |
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• The basic "Razor" syntax that you use for programming in ASP.NET Web Pages. |
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• |
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• |
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• How to install packages (components that contain prebuilt code) to use with your site. |
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• How to use helpers to perform common programming tasks. |
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Features/technologies discussed: |
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• NuGet and the package manager. |
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• The Twitter helper. |
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This tutorial is primarily an exercise in introducing you to the programming syntax that you'll use |
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for ASP.NET Web Pages. You'll learn about Razor syntax and code that's written in the C# |
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programming language. You got a glimpse of this syntax in the previous tutorial; in this tutorial |
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we'll explain the syntax more. |
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We promise that this tutorial involves the most programming that you'll see in a single tutorial, |
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and that it's the only tutorial that is only about programming. In the remaining tutorials in this set, |
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you'll actually create pages that do interesting things. |
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You'll also learn about helpers. A helper is a component — a packaged-up piece of code — that |
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you can add to a page. The helper performs work for you that otherwise might be tedious or |
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complex to do by hand. |
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Creating a Page to Play with Razor |
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In this section you'll play a bit with Razor so you can get a sense of the basic syntax. |
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Start WebMatrix if it's not already running. You'll use the website you created in the previous |
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tutorial (Getting Started). To reopen it, click Open Site and choose My Sites: |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 2: Programming Basics |
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19 |
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Choose the WebPagesMovies site, and then click OK. |
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Select the Files workspace. |
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In the ribbon, click New to create a page. Select CSHTML and name the new page |
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TestRazor.cshtml. |
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Click OK. |
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Copy the following into the file, completely replacing what's there already. |
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Note When you copy code or markup from the examples into a page, the indentation and |
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alignment might not be the same as in the tutorial. Indentation and alignment don't affect |
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how the code runs, though. |
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Introducing ASP.NET Web Pages 2 |
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Tutorial 2: Programming Basics |
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20 |
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@{ |
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// Working with numbers |
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var a = 4; |
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var b = 5; |
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var theSum = a + b; |
|
|
|
// Working with characters (strings) |
|
var technology = "ASP.NET"; |
|
var product ="Web Pages"; |
|
|
|
// Working with objects |
|
var rightNow = DateTime.Now; |
|
} |
|
|
|
<!DOCTYPE html> |
|
<html lang="en"> |
|
<head> |
|
<title>Testing Razor Syntax</title> |
|
<meta charset="utf-8" /> |
|
<style> |
|
body {font-family:Verdana; margin-left:50px; margin-top:50px;} |
|
div {border: 1px solid black; width:50%; margin:1.2em;padding:1em;} |
|
span.bright {color:red;} |
|
</style> |
|
</head> |
|
<body> |
|
<h1>Testing Razor Syntax</h1> |
|
<form method="post"> |
|
|
|
<div> |
|
<p>The value of <em>a</em> is @a. The value of <em>b</em> is @b. |
|
<p>The sum of <em>a</em> and <em>b</em> is <strong>@theSum</strong>.</p> |
|
<p>The product of <em>a</em> and <em>b</em> is <strong>@(a*b)</strong>.</p> |
|
</div> |
|
|
|
<div> |
|
<p>The technology is @technology, and the product is @product.</p> |
|
<p>Together they are <span class="bright">@(technology + " " + |
|
product)</span></p> |
|
</div> |
|
|
|
<div> |
|
<p>The current date and time is: @rightNow</p> |
|
<p>The URL of the current page is<br/><br/><code>@Request.Url</code></p> |
|
</div> |
|
|
|
</form> |
|
</body> |
|
</html> |
|
|
|
Examining the Example Page |
|
|
|
Most of what you see is ordinary HTML. However, at the top there's this code block: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
21 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
@{ |
|
// Working with numbers. |
|
var a = 4; |
|
var b = 5; |
|
var theSum = a + b; |
|
|
|
// Working with characters (strings). |
|
var technology = "ASP.NET"; |
|
var product ="Web Pages"; |
|
|
|
// Working with objects. |
|
var rightNow = DateTime.Now; |
|
} |
|
|
|
Notice the following things about this code block: |
|
|
|
• The @ character tells ASP.NET that what follows is Razor code, not HTML. ASP.NET will |
|
|
|
treat everything after the @ character as code until it runs into some HTML again. (In this |
|
case, that's the <!DOCTYPE> element. |
|
|
|
• The braces ( { and } ) enclose a block of Razor code if the code has more than one line. |
|
|
|
The braces tell ASP.NET where the code for that block starts and ends. |
|
|
|
• The // characters mark a comment — that is, a part of the code that won't execute. |
|
|
|
• Each statement has to end with a semicolon (;). (Not comments, though.) |
|
|
|
• You can store values in variables, which you create (declare) with the keyword var.When |
|
|
|
you create a variable, you give it a name, which can include letters, numbers, and |
|
underscore (_). Variable names can't start with a number and can't use the name of a |
|
programming keyword (like var). |
|
|
|
• You enclose character strings (like "ASP.NET" and "Web Pages") in quotation marks. (They |
|
|
|
must be double quotation marks.) Numbers are not in quotation marks. |
|
|
|
• Whitespace outside of quotation marks doesn't matter. Line breaks mostly don't matter; |
|
the exception is that you can't split a string in quotation marks across lines. Indentation |
|
and alignment don't matter. |
|
|
|
Something that's not obvious from this example is that all code is case sensitive. This means that |
|
the variable TheSum is a different variable than variables that might be named theSum or thesum. |
|
Similarly, var is a keyword, but Var is not. |
|
|
|
Objects and properties and methods |
|
|
|
Then there's the expression DateTime.Now. In simple terms, DateTime is an object. An object is a |
|
thing that you can program with—a page, a text box, a file, an image, a web request, an email |
|
message, a customer record, etc. Objects have one or more properties that describe their |
|
characteristics. A text box object has a Text property (among others), a request object has a |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
22 |
|
|
|
|
|
|
|
Urlproperty (and others), an email message has a From property and a To property, and so on. |
|
Objects also have methods that are the "verbs" they can perform. You'll be working with objects a |
|
lot. |
|
|
|
As you can see from the example, DateTime is an object that lets you program dates and times. It |
|
has a property named Now that returns the current date and time. |
|
|
|
Using code to render markup in the page |
|
|
|
In the body of the page, notice the following: |
|
|
|
<div> |
|
<p>The value of <em>a</em> is @a. The value of <em>b</em> is @b. |
|
<p>The sum of <em>a</em> and <em>b</em> is <strong>@theSum</strong>.</p> |
|
<p>The product of <em>a</em> and <em>b</em> is <strong>@(a*b)</strong>.</p> |
|
</div> |
|
|
|
<div> |
|
<p>The technology is @technology, and the product is @product.</p> |
|
<p>Together they are <span class="bright">@(technology + " " + |
|
product)</span></p> |
|
</div> |
|
|
|
<div> |
|
<p>The current date and time is: @rightNow</p> |
|
<p>The URL of the current page is<br/><br/><code>@Request.Url</code></p> |
|
</div> |
|
|
|
Again, the @ character tells ASP.NET that what follows is code, not HTML. In the markup you can |
|
add @ followed by a code expression, and ASP.NET will render the value of that expression right at |
|
that point. In the example, @a will render whatever the value is of the variable named a, @product |
|
renders whatever is in the variable named product, and so on. |
|
|
|
You're not limited to variables, though. In a few instances here, the @ character precedes an |
|
expression: |
|
|
|
• |
|
|
|
• |
|
|
|
• |
|
|
|
@(a*b) renders the product of whatever is in the variables a and b. (The * operator means |
|
multiplication.) |
|
@(technology + " " + product) renders the values in the variables technology and |
|
product after concatenating them and adding a space in between. The operator (+) for |
|
concatenating strings is the same as the operator for adding numbers. ASP.NET can |
|
usually tell whether you're working with numbers or with strings and does the right thing |
|
with the + operator. |
|
@Request.Url renders the Url property of the Request object. The Request object contains |
|
information about the current request from the browser, and of course the Url property |
|
contains the URL of that current request. |
|
|
|
The example is also designed to show you that you can do work in different ways. You can do |
|
calculations in the code block at the top, put the results into a variable, and then render the |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
23 |
|
|
|
|
|
|
|
variable in markup. Or you can do calculations in an expression right in the markup. The approach |
|
you use depends on what you're doing and, to some extent, on your own preference. |
|
|
|
Seeing the code in action |
|
|
|
Right-click the name of the file and then choose Launch in browser. You see the page in the |
|
browser with all the values and expressions resolved in the page. |
|
|
|
(Remember that the URL that you see in the browser might use a different port number than |
|
what you see in these screenshots. Instead of locahost:56011, you'll see localhost followed by a |
|
different number.) |
|
|
|
Look at the source in the browser. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
24 |
|
|
|
|
|
As you expect from your experience in the previous tutorial, none of the Razor code is in the page. |
|
All you see are the actual display values. When you run a page, you're actually making a request |
|
to the web server that's built into WebMatrix. When the request is received, ASP.NET resolves all |
|
the values and expressions and renders their values into the page. It then sends the page to the |
|
browser. |
|
|
|
Razor and C# |
|
|
|
Up to now we've said that you're working with Razor syntax. That's true, but it's not the complete |
|
story. The actual programming language you're using is called C#. C# was created by Microsoft |
|
over a decade ago and has become one of the primary programming languages for creating |
|
Windows apps. All the rules you've seen about how to name a variable and how to create |
|
statements and so on are actually all rules of the C# language. |
|
|
|
Razor refers more specifically to the small set of conventions for how you embed this code into a |
|
page. For example, the convention of using @ to mark code in the page and using @{ } to embed a |
|
code block is the Razor aspect of a page. Helpers are also considered to be part of Razor. Razor |
|
syntax is used in more places than just in ASP.NET Web Pages. (For example, it's used in ASP.NET |
|
MVC views as well.) |
|
|
|
We mention this because if you look for information about programming ASP.NET Web Pages, |
|
you'll find lots of references to Razor. However, a lot of those references don't apply to what |
|
you're doing and might therefore be confusing. And in fact, many of your programming questions |
|
are really going to be about either working with C# or working with ASP.NET. So if you look |
|
specifically for information about Razor, you might not find the answers you need. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
25 |
|
|
|
|
|
Adding Some Conditional Logic |
|
|
|
One of the great features about using code in a page is that you can change what happens based |
|
on various conditions. In this part of the tutorial, you'll play around with some ways to change |
|
what's displayed in the page. |
|
|
|
The example will be simple and somewhat contrived so that we can concentrate on the |
|
conditional logic. The page you'll create will do this: |
|
|
|
• |
|
|
|
Show different text on the page depending on whether it's the first time the page is |
|
displayed or whether you've clicked a button to submit the page. That will be the first |
|
conditional test. |
|
|
|
• Display the message only if a certain value is passed in the query string of the URL |
|
|
|
(http://...?show=true). That will be the second conditional test. |
|
|
|
In WebMatrix, create a page and name it TestRazorPart2.cshtml. (In the ribbon, click New, choose |
|
CSHTML, name the file, and then click OK.) |
|
|
|
Replace the contents of that page with the following: |
|
|
|
@{ |
|
var message = "This is the first time you've requested the page."; |
|
} |
|
<!DOCTYPE html> |
|
<html lang="en"> |
|
<head> |
|
<title>Testing Razor Syntax - Part 2</title> |
|
<meta charset="utf-8" /> |
|
<style> |
|
body {font-family:Verdana; margin-left:50px; margin-top:50px;} |
|
div {border: 1px solid black; width:50%; margin:1.2em;padding:1em;} |
|
</style> |
|
</head> |
|
<body> |
|
<h1>Testing Razor Syntax - Part 2</h1> |
|
<form method="post"> |
|
<div> |
|
<p>@message</p> |
|
<p><input type="submit" value="Submit" /></p> |
|
</div> |
|
</form> |
|
</body> |
|
</html> |
|
|
|
The code block at the top initializes a variable named message with some text. In the body of the |
|
page, the contents of the message variable are displayed inside a <p> element. The markup also |
|
contains an <input> element to create a Submit button. |
|
|
|
Run the page to see how it works now. For now, it's basically a static page, even if you click the |
|
Submit button. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
26 |
|
|
|
Go back to WebMatrix. Inside the code block, add the following code after the line that initializes |
|
message: |
|
|
|
if(IsPost){ |
|
message = "Now you've submitted the page."; |
|
} |
|
|
|
The if{ } block |
|
|
|
What you just added was an if condition. In code, the if condition has a structure like this: |
|
|
|
if(some condition){ |
|
One or more statements here that run if the condition is true; |
|
} |
|
|
|
The condition to test is in parentheses. It has to be a value or an expression that returns true or |
|
false. If the condition is true, ASP.NET runs the statement or statements that are inside the |
|
braces. (Those are the then part of the if-then logic.) If the condition is false, the block of code is |
|
skipped. |
|
|
|
Here are a few examples of conditions you can test in an if statement: |
|
|
|
if( currentValue > 12 ){ ... } |
|
|
|
if( dueDate <= DateTime.Today ) { ... } |
|
|
|
if( IsDone == true ) { ... } |
|
|
|
if( IsPost ) { ... } |
|
|
|
if( !IsPost ) { ... } |
|
|
|
if(a != 0) { ... } |
|
|
|
if( fileProcessingIsDone != true && displayMessage == false ) { ... } |
|
|
|
You can test variables against values or against expressions by using a logical operator or |
|
comparison operator: equal to (==), greater than (>), less than (<), greater than or equal to (>=), |
|
and less than or equal to (<=). The != operator means not equal to — for example, if(a != 0) |
|
means if a is not equal to 0. |
|
|
|
Note Make sure you notice that the comparison operator for equals to (==) is not the |
|
same as =. The = operator is used only to assign values (var a=2). If you mix these |
|
operators up, you'll either get an error or you'll get some strange results. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
27 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
To test whether something is true, the complete syntax is if(IsDone == true). But you can also |
|
use the shortcut if(IsDone). If there's no comparison operator, ASP.NET assumes that you're |
|
testing for true. |
|
|
|
The ! operator by itself means a logical NOT. For example, the condition if(!IsPost) means if |
|
IsPost is not true. |
|
|
|
You can combine conditions by using a logical AND (&& operator) or logical OR (|| operator). For |
|
example, the last of the if conditions in the preceding examples means if FileProcessingIsDone is |
|
set to true AND displayMessage is set to false. |
|
|
|
The else block |
|
|
|
One final thing about if blocks: an if block can be followed by an else block. An else block is |
|
useful is you have to execute different code when the condition is false. Here's a simple example: |
|
|
|
var message = ""; |
|
if(errorOccurred == true) |
|
{ |
|
message = "Sorry, an error occurred."; |
|
} |
|
else |
|
{ |
|
message = "The process finished without errors!"; |
|
} |
|
|
|
You'll see some examples in later tutorials in this series where using an else block is useful. |
|
|
|
Testing whether the request is a submit (post) |
|
|
|
There's more, but let's get back to the example, which has the condition if(IsPost){ ... }. |
|
IsPost is actually a property of the current page. The first time the page is requested, IsPost |
|
returns false. However, if you click a button or otherwise submit the page — that is, you post it — |
|
IsPost returns true. So IsPost lets you determine whether you're dealing with a form submission. |
|
(In terms of HTTP verbs, if the request is a GET operation, IsPost returns false. If the request is a |
|
POST operation, IsPost returns true.) In a later tutorial you'll work with input forms, where this |
|
test becomes particularly useful. |
|
|
|
Run the page. Because this is the first time you're requested the page, you see "This is the first |
|
time you've requested the page". That string is the value that you initialized the message variable |
|
to. There's an if(IsPost) test, but that returns false at the moment, so the code inside the if |
|
block doesn't run. |
|
|
|
Click the Submit button. The page is requested again. As before, the message variable is set to |
|
"This is the first time ...".But this time, the test if(IsPost) returns true, so the code inside the |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
28 |
|
|
|
ifblock runs. The code changes the value of the message variable to a different value, which is |
|
what's rendered in the markup. |
|
|
|
Now add an if condition in the markup. Below the <p> element that contains the Submit button, |
|
add the following markup: |
|
|
|
@if(IsPost){ |
|
<p>You submitted the page at @DateTime.Now</p> |
|
} |
|
|
|
You're adding code inside the markup, so you have to start with @. Then there's an if test similar |
|
to the one you added earlier up in the code block. Inside the braces, though, you're adding |
|
ordinary HTML — at least, it's ordinary until it gets to @DateTime.Now. This is another little bit of |
|
Razor code, so again you have to add @ in front of it. |
|
|
|
The point here is that you can add if conditions in both the code block at the top and in the |
|
markup. If you use an if condition in the body of the page, the lines inside the block can be |
|
markup or code. In that case, and as is true anytime you mix markup and code, you have to use @ |
|
to make it clear to ASP.NET where the code is. |
|
|
|
Run the page and click Submit.This time you not only see a different message when you submit |
|
("Now you've submitted ..."), but you see a new message that lists the date and time. |
|
|
|
Testing the value of a query string |
|
|
|
One more test. This time, you'll add an if block that tests a value named show that might be |
|
passed in the query string.(Like this: http://localhost:43097/TestRazorPart2.cshtml?show=true) |
|
You'll change the page so that the message you've been displaying ("This is the first time ...", etc.) |
|
is only displayed if the value of show is true. |
|
|
|
At the bottom (but inside) the code block at the top of the page, add the following: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
29 |
|
|
|
|
|
|
|
var showMessage = false; |
|
if(Request.QueryString["show"].AsBool() == true){ |
|
showMessage = true; |
|
} |
|
|
|
The complete code block now looks like the following example. (Remember that when you copy |
|
the code into your page, the indentation might look different. But that doesn't affect how the |
|
code runs.) |
|
|
|
@{ |
|
var message = "This is the first time you've requested the page."; |
|
|
|
if(IsPost){ |
|
message = "Now you've submitted the page."; |
|
} |
|
|
|
var showMessage = false; |
|
if(Request.QueryString["show"].AsBool() == true){ |
|
showMessage = true; |
|
} |
|
} |
|
|
|
The new code in the block initializes a variable named showMessage to false. It then does an if test |
|
to look for a value in the query string. When you first request the page, it has a URL like this one: |
|
|
|
http://localhost:43097/TestRazorPart2.cshtml |
|
|
|
The code determines whether the URL contains a variable named show in the query string, like this |
|
version of the URL: |
|
|
|
http://localhost:43097/TestRazorPart2.cshtml?show=true |
|
|
|
The test itself looks at the QueryString property of the Request object. If the query string contains |
|
an item named show, and if that item is set to true, the if block runs and sets the showMessage |
|
variable to true. |
|
|
|
There's a trick here, as you can see. Like the name says, the query string is a string. However, you |
|
can only test for true and false if the value you're testing is a Boolean (true/false) value. Before |
|
you can test the value of the show variable in the query string, you have to convert it to a Boolean |
|
value. That's what the AsBool method does — it takes a string as input and converts it to a |
|
Boolean value. Clearly, if the string is "true", the AsBool method converts that value to true.If the |
|
value of the string is anything else, AsBool returns false. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
30 |
|
|
|
|
|
|
|
|
|
Data Types and As( ) Methods |
|
|
|
We've only said so far that when you create a variable, you use the keyword var. That's not the |
|
entire story, though. In order to manipulate values — to add numbers, or concatenate strings, or |
|
compare dates, or test for true/false — C# has to work with an appropriate internal |
|
representation of the value. C# can usually figure out what that representation should be (that is, |
|
what type the data is) based on what you're doing with the values. Now and then, though, it can't |
|
do that. If not, you have to help out by explicitly indicating how C# should represent the data. The |
|
AsBool method does that — it tells C# that a string value of "true" or "false" should be treated as |
|
a Boolean value. Similar methods exist to represent strings as other types as well, like AsInt (treat |
|
as an integer), AsDateTime (treat as a date/time), AsFloat (treat as a floating-point number), and |
|
so on. When you use these As( ) methods, if C# can't represent the string value as requested, |
|
you'll see an error. |
|
|
|
In the markup of the page, remove or comment out this element (here it's shown commented |
|
out): |
|
|
|
<!-- <p>@message</p> --> |
|
|
|
Right where you removed or commented out that text, add the following: |
|
|
|
@if(showMessage){ |
|
<p>@message</p> |
|
} |
|
|
|
The if test says that if the showMessage variable is true, render a <p> element with the value of the |
|
message variable. |
|
|
|
Summary of your conditional logic |
|
|
|
In case you're not entirely sure of what you've just done, here's a summary. |
|
|
|
• The message variable is initialized to a default string ("This is the first time ..."). |
|
• |
|
|
|
If the page request is the result of a submit (post), the value of message is changed to |
|
"Now you've submitted ..." |
|
|
|
• The showMessage variable is initialized to false. |
|
• |
|
• |
|
|
|
If the query string contains ?show=true , the showMessage variable is set to true. |
|
In the markup, if showMessage is true, a <p> element is rendered that shows the value of |
|
message. (If showMessage is false, nothing is rendered at that point in the markup.) |
|
In the markup, if the request is a post, a <p> element is rendered that displays the date |
|
and time. |
|
|
|
• |
|
|
|
Run the page. There's no message, because showMessage is false, so in the markup the |
|
if(showMessage) test returns false. |
|
|
|
Introducing ASP.NET Web Pages 2 |
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|
|
Tutorial 2: Programming Basics |
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|
|
31 |
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|
|
Click Submit. You see the date and time, but still no message. |
|
|
|
In your browser, go to the URL box and add the following to the end of the URL: ?show=true and |
|
then press Enter. |
|
|
|
The page is displayed again. (Because you changed the URL, this is a new request, not a submit.) |
|
Click Submit again. The message is displayed again, as is the date and time. |
|
|
|
In the URL, change ?show=true to ?show=false and press Enter. Submit the page again. The page is |
|
back to how you started — no message. |
|
|
|
As noted earlier, the logic of this example is a little contrived. However, if is going to come up in |
|
many of your pages, and it will take one or more of the forms you've seen here. |
|
|
|
Installing a Helper (Displaying a Twitter Feed) |
|
|
|
Some tasks that people often want to do on web pages require a lot of code or require extra |
|
knowledge. Examples: displaying a chart for data; putting a Facebook "Like" button on a page; |
|
sending email from your website; cropping or resizing images; using PayPal for your site. To make |
|
it easy to do these kinds of things, ASP.NET Web Pages lets you use helpers. Helpers are |
|
components that you install for a site and that let you perform typical tasks by using just a few |
|
lines of Razor code. |
|
|
|
ASP.NET Web Pages has a few helpers built in. However, many helpers are available in packages |
|
(add-ins) that are provided using the NuGet package manager. NuGet lets you select a package to |
|
install and then it takes care of all the details of the installation. |
|
|
|
In this part of the tutorial, you'll install a helper that lets you manage a Twitter feed. You'll learn |
|
two things. One is how to find and install a helper. You'll also learn how a helper makes it easy to |
|
do something you'd otherwise need to do by using a lot of code you'd have to write yourself. |
|
|
|
Introducing ASP.NET Web Pages 2 |
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|
|
Tutorial 2: Programming Basics |
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|
|
32 |
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|
|
|
|
|
In WebMatrix, click the Gallery button. |
|
|
|
This launches the NuGet package manager and displays available packages. (Not all of the |
|
packages are helpers; some add functionality to WebMatrix itself, some are additional templates, |
|
and so on.) |
|
|
|
In the search box, enter "Twitter". NuGet shows the packages that have Twitter functionality. |
|
(The link underneath the package icon links to details about that package.) |
|
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|
Introducing ASP.NET Web Pages 2 |
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|
|
Tutorial 2: Programming Basics |
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|
|
33 |
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|
|
Select the Twitter.Helper package and then click Install to launch the installer. When it's |
|
done,you see a message in the notification area at the bottom of the screen. |
|
|
|
That's it. NuGet downloads and installs everything, including any additional components that |
|
might be required (dependencies). Since this is the first time you've installed a helper, NuGet also |
|
creates folders in your website for the code that makes up the helper. |
|
|
|
If for some reason you have to uninstall a helper, the process is very similar. Click the Gallery |
|
button, click the Installed tab, and pick the package you want to uninstall. |
|
|
|
Using a Helper in a Page |
|
|
|
Now you'll use the Twitter helper that you just installed. The process for adding a helper to a page |
|
is similar for most helpers. |
|
|
|
In WebMatrix, create a page and name it TwitterTest.cshml. (You're creating a special page to test |
|
the helper, but you can use helpers in any page in your site.) |
|
|
|
Inside the <body> element, add a <div> element. Inside the <div> element, type this: |
|
|
|
@TwitterGoodies. |
|
|
|
The @ character is the same character you've been using to mark Razor code. TwitterGoodies is |
|
the helper object that you're working with. |
|
|
|
As soon as you type the period (.), WebMatrix displays a list of methods (functions) that the |
|
TwitterGoodies helper makes available: |
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|
|
Introducing ASP.NET Web Pages 2 |
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|
|
Tutorial 2: Programming Basics |
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|
|
34 |
|
|
|
|
|
|
|
This feature is known as IntelliSense. It helps you code by providing context-appropriate choices. |
|
IntelliSense works with HTML, CSS, ASP.NET code, JavaScript, and other languages that are |
|
supported in WebMatrix. It's another feature that makes it easier to develop web pages in |
|
WebMatrix. |
|
|
|
Press S on the keyboard, and you see that IntelliSense finds the Search method: |
|
|
|
Press Tab. IntelliSense inserts the selected method (Search) for you. Type an open parenthesis ( ( |
|
), then the string "webmatrix" in quotation marks, then a closing parenthesis ( ) ). When you're |
|
done, the line looks like this: |
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|
|
@TwitterGoodies.Search("webmatrix") |
|
|
|
The Search method finds tweets that contain the string that you specify — in this case, it will look |
|
for tweets that mention "webmatrix". (Either in text or in hashtags.) |
|
|
|
Run the page. You see a Twitter feed. (It might take a few moments for the feed to start |
|
populating.) |
|
|
|
Introducing ASP.NET Web Pages 2 |
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|
|
Tutorial 2: Programming Basics |
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|
|
35 |
|
|
|
|
|
To get an idea of what the helper is doing for you, view the source of the page in the |
|
browser.Along with the HTML that you had in your page, you see a block of JavaScript code that |
|
looks roughly like the following block. (It might be all on one line or otherwise compressed.) |
|
|
|
<script> new TWTR.Widget({ version: 2, type: 'search', search: 'webmatrix', interval: |
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|
|
6000, title: '', subject: '', width: 250, height: 300, theme: { shell: { background: |
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|
|
'#8ec1da', color: '#ffffff' }, tweets: { background: '#ffffff', color: '#444444', links: |
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|
|
'#1985b5' } }, features: { scrollbar: false, loop: true, live: true, hashtags: true, |
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|
|
timestamp: true, avatars: true, toptweets: true, behavior: 'all' } }).render().start(); |
|
</script> |
|
|
|
This is code that the helper rendered into the page at the place where you had |
|
@TwitterGoodies.Search. (There's also some markup that's not shown here.) The helper took the |
|
information you provided and generated the code that talks directly to Twitter in order to get |
|
back the Twitter feed that you see. If you know the Twitter programming interface (API), you can |
|
create this code yourself. But because the helper can do it for you, you don't have to know the |
|
details of how to communicate with Twitter. And even if you are familiar with the Twitter API, it's |
|
a lot easier to include the TwitterGoodies helper on the page and let it do the work. |
|
|
|
Return to the page. At the bottom, inside the <body> element, add the following code. Substitute |
|
your own Twitter account name if you have one. |
|
|
|
<div> |
|
@TwitterGoodies.FollowButton("microsoft") |
|
</div> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
36 |
|
|
|
|
|
This code calls the FollowButton method of the TwitterGoodies helper. As you can guess, the |
|
method adds a Follow Me on Twitter button. You pass a Twitter name to this method to indicate |
|
who to follow. |
|
|
|
Run the page and you see the Follow Me button: |
|
|
|
Click it, and you go to the Twitter page for the user you specified. |
|
|
|
As before, you can look at the source of the page in the browser to see what the Twitter helper |
|
generated for you. This time the code looks something like the following example: |
|
|
|
<a href="http://www.twitter.com/microsoft"><img src="http://twitter- |
|
badges.s3.amazonaws.com/follow_me-a.png" alt="Follow microsoft on Twitter"/></a> |
|
|
|
Again, you could have written this code yourself, but the helper makes it much easier. |
|
|
|
Server-Side (Razor) and Client-Side (JavaScript) Programming |
|
|
|
How does Razor code in an ASP.NET Web Pages relate to JavaScript code that runs in the |
|
browser? If you've got experience with JavaScript, you might realize as you work with these |
|
tutorials that many of the tasks could also be done in JavaScript. That's true, especially with the |
|
simple examples you've seen so far. |
|
|
|
A .cshtml page can contain both Razor code and JavaScript code. The traditional division of labor |
|
has been that server code handled tasks that it made sense to run on the server. This included |
|
accessing resources like a shared database and performing various types of business logic. In |
|
contrast, client code has typically been used to create a rich user experience. Pop-up calendars, |
|
sliders, animations, and many other UI effects are created by client code, and can all be done |
|
easily using JavaScript libraries (especially jQuery). |
|
|
|
These days the distinction has blurred a little because client code libraries now let you |
|
communicate with the server in ways that formerly could only be done in server code. In general, |
|
though, it's still useful to think of server code (Razor and C#) as being for back-end work and client |
|
code (JavaScript) as useful for UI. In subsequent tutorial sets you'll learn how to integrate |
|
JavaScript into a .cshtml page for just this purpose, namely to create a lively user experience. |
|
|
|
Coming Up Next |
|
|
|
To keep this tutorial short, we had to focus on only a few basics. Naturally, there's a lot more to |
|
Razor and C#. You'll learn more as you go through these tutorials. If you're interested in learning |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
37 |
|
|
|
|
|
more about the programming aspects of Razor and C# right now, you can read a more thorough |
|
introduction here:Introduction to ASP.NET Web Programming Using the Razor Syntax. |
|
|
|
The next tutorial introduces you to working with a database. In that tutorial, you'll begin creating |
|
the sample application that lets you list your favorite movies. |
|
|
|
Additional Resources |
|
|
|
• Complete Listing for Test Razor Page |
|
• Complete Listing for TestRazorPart2 Page |
|
• Complete Listing for TwitterTest Page |
|
• |
|
|
|
Introduction to ASP.NET Web Programming Using the Razor Syntax |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 2: Programming Basics |
|
|
|
38 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
This tutorial shows you how to create a database in WebMatrix and how to display database data |
|
in a page when you use ASP.NET Web Pages (Razor). |
|
|
|
What you'll learn: |
|
|
|
• How to use WebMatrix tools to create a database and database tables. |
|
• How to use WebMatrix tools to add data to a database. |
|
• How to display data from the database on a page. |
|
• How to run SQL commands in ASP.NET Web Pages. |
|
• How to customize the WebGrid helper to change the data display and to add paging and |
|
|
|
sorting. |
|
|
|
Features/technologies discussed: |
|
|
|
• WebMatrix database tools. |
|
• |
|
|
|
WebGrid helper. |
|
|
|
What You'll Build |
|
|
|
In the previous tutorial, you were introduced to ASP.NET Web Pages (.cshtml files), to the basics |
|
of Razor syntax, and to helpers. In this tutorial, you'll begin creating the actual web application |
|
that you'll use for the rest of the series. The app is a simple movie application that lets you view, |
|
add, change, and delete information about movies. |
|
|
|
When you're done with this tutorial, you'll be able to view a movie listing that looks like this page: |
|
|
|
But to begin, you have to create a database. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
39 |
|
|
|
|
|
A Very Brief Introduction to Databases |
|
|
|
This tutorial will provide only the briefest introduction to databases. If you have database |
|
experience, you can skip this short section. |
|
|
|
A database contains one or more tables that contain information — for example, tables for |
|
customers, orders, and vendors,or for students, teachers, classes, and grades. Structurally, a |
|
database table is like a spreadsheet. Imagine a typical address book. For each entry in the address |
|
book (that is, for each person) you have several pieces of information such as first name, last |
|
name, address, email address, and phone number. |
|
|
|
(Rows are sometimes referred to as records, and columns are sometimes referred to as fields.) |
|
|
|
For most database tables, the table has to have a column that contains a unique value, like a |
|
customer number, account number, and so on. This value is known as the table's primary key, and |
|
you use it to identify each row in the table. In the example, the ID column is the primary key for |
|
the address book shown in the previous example. |
|
|
|
Much of the work you do in web applications consists of reading information out of the database |
|
and displaying it on a page. You'll also often gather information from users and add it to a |
|
database, or you'll modify records that are already in the database. (We'll cover all of these |
|
operations in the course of this tutorial set.) |
|
|
|
Database work can be enormously complex and can require specialized knowledge. For this |
|
tutorial set, though, you have to understand only basic concepts, which will all be explained as |
|
you go. |
|
|
|
Creating a Database |
|
|
|
WebMatrix includes tools that make it easy to create (or define) a database and to create tables in |
|
the database. For this tutorial set, you'll create a database that has only one table in it — Movies. |
|
|
|
Open WebMatrix if you haven't already done so, and open the WebPagesMovies site that you |
|
created in the previous tutorial. |
|
|
|
In the left pane, click the Database workspace. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
40 |
|
|
|
|
|
The ribbon changes to show database-related tasks. In the ribbon, click New Database. |
|
|
|
WebMatrix creates a database (an .sdf file) that has the same name as your site — |
|
WebPagesMovies.sdf. (You won't do this here, but you can rename the file to anything you like, as |
|
long as it has an .sdf extension.) |
|
|
|
Creating a Table |
|
|
|
In the ribbon, click New Table. WebMatrix opens the table designer in a new tab. (If the New |
|
Table option isn't available, make sure that the new database is selected in the tree view on the |
|
left.) |
|
|
|
In the text box at the top (where the watermark says "Enter table name"), enter "Movies". |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
41 |
|
|
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|
|
|
|
|
|
The pane underneath the table name is where you define individual columns. For the Movies |
|
table in this tutorial, you'll create only a few columns: ID, Title, Genre, and Year. |
|
|
|
In the Name box, enter "ID". Entering a value here activates all the controls for the new column. |
|
|
|
Tab to the Data Type list and choose int. This value specifies that the ID column will contain |
|
integer (number) data. |
|
|
|
Note We won't call it out any more here (much), but you can use standard Windows |
|
keyboard gestures to navigate in this grid. For example, you can tab between fields, you |
|
can just start typing in order to select an item in a list, and so on. |
|
|
|
Tab past the Default Value box (that is, leave it blank). Tab to the Is Primary Key check box and |
|
select it. This option tells the database that the ID column will contain the data that identifies |
|
individual rows. (That is, each row will have a unique value in the ID column that you can use to |
|
find that row.) |
|
|
|
Choose the Is Identity option. This option tells the database that it should automatically generate |
|
the next sequential number for each new row. (The Is Identity option works only if you've also |
|
selected the Is Primary Key option.) |
|
|
|
Click in the next grid row, or press Tab twice to finish the current row. Either gesture saves the |
|
current row and starts the next one. Notice that the Default Value column now says Null. (Null is |
|
the default value for the default value, so to speak.) |
|
|
|
When you've finished defining the new ID column, the designer will look like this illustration: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
42 |
|
|
|
|
|
To create the next column, click in the box in the Name column. Enter "Title" for the column and |
|
then select nvarchar for the Data Type value. The "var" part of nvarchar tells the database that |
|
the data for this column will be a string whose size might vary from record to record. (The "n" |
|
prefix represents "national," which indicates that the field can hold character data for any |
|
alphabet or writing system — that is, the field holds Unicode data.) |
|
|
|
When you choose nvarchar, another box appears where you can enter the maximum length for |
|
the field. Enter 50, on the assumption that no movie title that you'll work with in this tutorial will |
|
be longer than 50 characters. |
|
|
|
Skip Default Value and clear the Allow Nulls option. You don't want the database to allow any |
|
movies to be entered into the database that don't have a title. |
|
|
|
When you're done and move to the next row, the designer looks like this illustration: |
|
|
|
Repeat these steps to create a column named "Genre", except for the length, set it to just 30. |
|
|
|
Create another column named "Year." For the data type, choose nchar (not nvarchar) and set the |
|
length to 4. For the year, you're going to use a 4-digit number like "1995" or "2010", so you don't |
|
require a variable-sized column. |
|
|
|
Here's what the finished design looks like: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
43 |
|
|
|
|
|
|
|
|
|
Press Ctrl+S or click the Save button in the Quick Access toolbar. Close the database designer by |
|
closing the tab. |
|
|
|
Adding Some Example Data |
|
|
|
Later in this tutorial series you'll create a page where you can enter new movies in a form. For |
|
now, however, you can add some example data that you can then display on a page. |
|
|
|
In the Database workspace in WebMatrix, notice that there's a tree that shows you the .sdf file |
|
you created earlier. Open the node for your new .sdf file, and then open the Tables node. |
|
|
|
Right-click the Movies node and then choose Data. WebMatrix opens a grid where you can enter |
|
data for the Movies table: |
|
|
|
Click the Title column and enter "When Harry Met Sally". Move to the Genre column (you can use |
|
the Tab key) and enter "Romantic Comedy". Move to the Year column and enter "1989": |
|
|
|
Press Enter, and WebMatrix saves the new movie. Notice that the ID column has been filled in. |
|
|
|
Enter another movie (for example, "Gone with the Wind", "Drama", "1939"). The ID column is |
|
filled in again: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
44 |
|
|
|
|
|
|
|
|
|
|
|
Enter a third movie (for example, "Ghostbusters", "Comedy"). As an experiment, leave the Year |
|
column blank and then press Enter. Because you unselected the Allow Nulls option, the database |
|
shows an error: |
|
|
|
Click OK to go back and fix the entry (the year for "Ghostbusters" is 1984), and then press Enter. |
|
|
|
Fill in several movies until you have 8 or so. (Entering 8 makes it easier to work with paging later. |
|
But if that's too many, enter just a few for now.) The actual data doesn't matter. |
|
|
|
If you entered all the movies without any errors, the ID values are sequential. If you tried to save |
|
an incomplete movie record, the ID numbers might not be sequential. If so, that's okay. The |
|
numbers don't have any inherent meaning, and the only thing that's important is that they're |
|
unique in the Movies table. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
45 |
|
|
|
|
|
|
|
|
|
Close the tab that contains the database designer. |
|
|
|
Now you can turn to displaying this data on a web page. |
|
|
|
Adding the Web Data Package |
|
|
|
You access data in ASP.NET Web Pages sites using helpers that are available in the WebData |
|
package. Because you used the Empty Site template in WebMatrix to create your Movies site, the |
|
WebData package isn't automatically included. Therefore, you have to add the package to your |
|
site. |
|
|
|
In the left pane, click the Files workspace. |
|
|
|
In the ribbon, click the Gallery button. |
|
|
|
The NuGet Gallery is displayed. |
|
|
|
In the search box, enter "Microsoft.AspNet.WebPages.WebData" to narrow down the list of |
|
packages that are displayed. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
46 |
|
|
|
|
|
|
|
Select the Microsoft ASP.NET Web Pages 2 Web Data package and then click Install. |
|
|
|
The Gallery page displays details about the package. |
|
|
|
Click Install. After you accept the license, WebMatrix installs the Web Data package. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
47 |
|
|
|
|
|
|
|
Now you're ready to display data on a page. |
|
|
|
Displaying Data in a Page by Using the WebGrid Helper |
|
|
|
To display data in a page, you're going to use the WebGrid helper. This helper produces a display in |
|
a grid or table (rows and columns). As you'll see, you'll be able refine the grid with formatting and |
|
other features. |
|
|
|
To run the grid, you'll have to write a few lines of code. These few lines will serve as a kind of |
|
pattern for almost all of the data access that you do in this tutorial. |
|
|
|
Note You actually have many options for displaying data on a page; the WebGrid helper is |
|
just one. We chose it for this tutorial because it's the easiest way to display data and |
|
because it's reasonably flexible. In the next tutorial set, you'll see how to use a more |
|
"manual" way to work with data in the page, which gives you more direct control over how |
|
to display the data. |
|
|
|
In the left pane in WebMatrix, click the Files workspace. In the tree view, select the root of the |
|
website. |
|
|
|
The new database you created is in the App_Data folder. If the folder didn't already exist, |
|
WebMatrix created it for your new database. (The folder might have existed if you'd previously |
|
installed helpers.) |
|
|
|
In the ribbon, click New. In the Choose a File Type box, choose CSHTML. |
|
|
|
In the Name box, name the new page "Movies.cshtml": |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
48 |
|
|
|
Click the OK button. WebMatrix opens a new file with some skeleton elements in it. First you'll |
|
write some code to go get the data from the database. Then you'll add markup to the page to |
|
actually display the data. |
|
|
|
Writing the Data Query Code |
|
|
|
At the top of the page, between the @{ and } characters, enter the following code. (Make sure |
|
that you enter this code between the opening and closing braces.) |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
var selectedData = db.Query("SELECT * FROM Movies"); |
|
var grid = new WebGrid(source: selectedData); |
|
|
|
The first line opens the database that you created earlier, which is always the first step before |
|
doing something with the database. You tell the Database.Open method name of the database to |
|
open. Notice that you don't include .sdf in the name. The Open method assumes that it's looking |
|
for an .sdf file (that is, WebPagesMovies.sdf) and that the .sdf file is in the App_Data folder. |
|
(Earlier we noted that the App_Data folder is reserved; this scenario is one of the places where |
|
ASP.NET makes assumptions about that name.) |
|
|
|
When the database is opened, a reference to it is put into the variable named db. (Which could be |
|
named anything.) The db variable is how you'll end up interacting with the database. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
49 |
|
|
|
|
|
The second line actually fetches the database data by using the Query method. Notice how this |
|
code works: the db variable has a reference to the opened database, and you invoke the Query |
|
method by using the db variable (db.Query). |
|
|
|
Thequery itself is a SQL Select statement. (For a little background about SQL, see the explanation |
|
later.) In the statement, Movies identifies the table to query. The * character specifies that the |
|
query should return all the columns from the table. (You could also list columns individually, |
|
separated by commas.) |
|
|
|
The results of the query, if any, are returned and made available in the selectedData variable. |
|
Again, the variable could be named anything. |
|
|
|
Finally, the third line tells ASP.NET that you want to use an instance of the WebGrid helper. You |
|
create (instantiate) the helper object by using the new keyword and pass it the query results via |
|
the selectedData variable. The new WebGrid object, along with the results of the database query, |
|
are made available in the grid variable. You'll need that result in a moment to actually display the |
|
data in the page. |
|
|
|
At this stage, the database has been opened, you've gotten the data you want, and you've |
|
prepared the WebGrid helper with that data. Next is to create the markup in the page. |
|
|
|
Structured Query Language (SQL) |
|
|
|
SQL is a language that's used in most relational databases for managing data in a database. It |
|
includes commands that let you retrieve data and update it, and that let you create, modify, and |
|
manage data in database tables. SQL is different than a programming language (like C#). With |
|
SQL, you tell the database what you want, and it's the database's job to figure out how to get the |
|
data or perform the task. Here are examples of some SQL commands and what they do: |
|
|
|
Select * From Movies |
|
|
|
SELECT ID, Name, Price FROM Product WHERE Price > 10.00 ORDER BY Name |
|
|
|
The first Select statement gets all the columns (specified by *) from the Movies table. |
|
|
|
The second Select statement fetches the ID, Name, and Price columns from records in the |
|
Product table whose Price column value is more than 10. The command returns the results in |
|
alphabetical order based on the values of the Name column. If no records match the price criteria, |
|
the command returns an empty set. |
|
|
|
INSERT INTO Product (Name, Description, Price) VALUES ('Croissant', 'A flaky delight', |
|
1.99) |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
50 |
|
|
|
This command inserts a new record into the Product table, setting the Name column to |
|
"Croissant", the Description column to "A flaky delight", and the price to 1.99. |
|
|
|
Notice that when you're specifying a non-numeric value, the value is enclosed in single quotation |
|
marks (not double quotation marks, as in C#). You use these quotation marks around text or date |
|
values, but not around numbers. |
|
|
|
DELETE FROM Product WHERE ExpirationDate < '01/01/2008' |
|
|
|
This command deletes records in the Product table whose expiration date column is earlier than |
|
January 1, 2008. (The command assumes that the Product table has such a column, of course.) |
|
The date is entered here in MM/DD/YYYY format, but it should be entered in the format that's |
|
used for your locale. |
|
|
|
The Insert and Delete commands don’t return result sets. Instead, they return a number that |
|
tells you how many records were affected by the command. |
|
|
|
For some of these operations (like inserting and deleting records), the process that's requesting |
|
the operation has to have appropriate permissions in the database. That's why for production |
|
databases you often have to supply a user name and password when you connect to the |
|
database. |
|
|
|
There are dozens of SQL commands, but they all follow a pattern like the commands you see |
|
here. You can use SQL commands to create database tables, count the number of records in a |
|
table, calculate prices, and perform many more operations. |
|
|
|
Adding Markup to Display the Data |
|
|
|
Inside the <head> element, set contents of the <title> element to "Movies": |
|
|
|
<head> |
|
<meta charset="utf-8" /> |
|
<title>Movies</title> |
|
</head> |
|
|
|
Inside the <body> element of the page, add the following: |
|
|
|
<h1>Movies</h1> |
|
<div> |
|
@grid.GetHtml() |
|
</div> |
|
|
|
That's it. The grid variable is the value you created when you created the WebGrid object in code |
|
earlier. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
51 |
|
|
|
In the WebMatrix tree view, right-click the page and select Launch in browser.You'll see |
|
something like this page: |
|
|
|
(Remember that the URL that you see in the browser might use a different port number than |
|
what you see in these screenshots — instead of locahost:56011, you'll see localhost followed by a |
|
different number.) |
|
|
|
Click a column heading link to sort by that column. Being able to sort by clicking a heading is a |
|
feature that's built into the WebGrid helper. |
|
|
|
The GetHtml method, as its name suggests, generates markup that displays the data. By default, |
|
the GetHtml method generates an HTML <table> element. (If you want, you can verify the |
|
rendering by looking at the source of the page in the browser.) |
|
|
|
Modifying the Look of the Grid |
|
|
|
Using the WebGrid helper like you just did is easy, but the resulting display is plain. The WebGrid |
|
helper has all sorts of options that let you control how the data is displayed. There are far too |
|
many to explore in this tutorial, but this section will give you an idea of some of those options. A |
|
few additional options will be covered in later tutorials in this series. |
|
|
|
Specifying Individual Columns to Display |
|
|
|
To start, you can specify that you want to display only certain columns. By default, as you've seen, |
|
the grid shows all four of the columns from the Movies table. |
|
|
|
In the Movies.cshtml file, replace the @grid.GetHtml() markup that you just added with the |
|
following: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
52 |
|
|
|
|
|
|
|
|
|
@grid.GetHtml( |
|
columns: grid.Columns( |
|
grid.Column("Title"), |
|
grid.Column("Genre"), |
|
grid.Column("Year") |
|
) |
|
) |
|
|
|
To tell the helper which columns to display, you include a columns parameter for the GetHtml |
|
method and pass in a collection of columns. In the collection, you specify each column to include. |
|
You specify an individual column to display by including a grid.Column object, and pass in the |
|
name of the data column you want. (These columns must be included in the SQL query results — |
|
the WebGrid helper cannot display columns that were not returned by the query.) |
|
|
|
Launch the Movies.cshtml page in the browser again, and this time you get a display like the |
|
following one (notice that no ID column is displayed): |
|
|
|
Changing the Look of the Grid |
|
|
|
There are quite a few more options for displaying columns, some of which will be explored in later |
|
tutorials in this set. For now, this section will introduce you to ways in which you can style the grid |
|
as a whole. |
|
|
|
Inside the <head> section of the page, just before the closing </head> tag, add the following |
|
<style>element: |
|
|
|
<style type="text/css"> |
|
.grid { margin: 4px; border-collapse: collapse; width: 600px; } |
|
.grid th, .grid td { border: 1px solid #C0C0C0; padding: 5px; } |
|
.head { background-color: #E8E8E8; font-weight: bold; color: #FFF; } |
|
.alt { background-color: #E8E8E8; color: #000; } |
|
</style> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
53 |
|
|
|
|
|
This CSS markup defines classes named grid, head, and so on. You could also put these style |
|
definitions in a separate .css file and link that to the page. (In fact,you'll do that later in this |
|
tutorial set.) But to make things easy for this tutorial, they're inside the same page that displays |
|
the data. |
|
|
|
Now you can get the WebGrid helper to use these style classes. The helper has a number of |
|
properties (for example, tableStyle) for just this purpose — you assign a CSS style class name to |
|
them, and that class name is rendered as part of the markup that's rendered by the helper. |
|
|
|
Change the grid.GetHtml markup so that it now looks like this code: |
|
|
|
@grid.GetHtml( |
|
tableStyle: "grid", |
|
headerStyle: "head", |
|
alternatingRowStyle: "alt", |
|
columns: grid.Columns( |
|
grid.Column("Title"), |
|
grid.Column("Genre"), |
|
grid.Column("Year") |
|
) |
|
) |
|
|
|
What's new here is that you've added tableStyle, headerStyle, and alternatingRowStyle |
|
parameters to the GetHtml method. These parameters have been set to the names of the CSS |
|
styles that you added a moment ago. |
|
|
|
Run the page, and this time you see a grid that looks much less plain than before: |
|
|
|
To see what the GetHtml method generated, you can look at the source of the page in the |
|
browser. We won't go into detail here, but the important point is that by specifying parameters |
|
like tableStyle, you caused the grid to generate HTML tags like the following: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
54 |
|
|
|
|
|
<table class="grid"> |
|
|
|
The <table> tag has had a class attribute added to it that references one of the CSS rules that you |
|
added earlier. This code shows you the basic pattern — different parameters for the GetHtml |
|
method let you reference CSS classes that the method then generates along with the markup. |
|
What you do with the CSS classes is up to you. |
|
|
|
Adding Paging |
|
|
|
As the last task for this tutorial, you'll add paging to the grid. Right now it's no problem to display |
|
all your movies at once. But if you added hundreds of movies, the page display would get long. |
|
|
|
In the page code, change the line that creates the WebGrid object to the following code: |
|
|
|
var grid = new WebGrid(source: selectedData, rowsPerPage: 3); |
|
|
|
The only difference from before is that you've added a rowsPerPage parameter that's set to 3. |
|
|
|
Run the page. The grid displays 3 rows at a time, plus navigation links that let you page through |
|
the movies in your database: |
|
|
|
Coming Up Next |
|
|
|
In the next tutorial, you'll learn how to use Razor and C# code to get user input in a form. You'll |
|
add a search box to the Movies page so that you can find movies by title or genre. |
|
|
|
Additional Resources |
|
|
|
• Complete Listing for Movies Page |
|
• |
|
|
|
Introduction to ASP.NET Web Programming Using the Razor Syntax |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 3: Displaying Data |
|
|
|
55 |
|
|
|
|
|
|
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
This tutorial shows you the basics of how to create an input form and how to handle the user's |
|
input when you use ASP.NET Web Pages (Razor). And now that you've got a database, you'll use |
|
your form skills to let users find specific movies in the database. |
|
|
|
What you'll learn: |
|
|
|
• How to create a form by using standard HTML elements. |
|
• How to read the user's input in a form. |
|
• How to create a SQL query that selectively gets data by using a search term that the user |
|
|
|
supplies. |
|
|
|
• How to have fields in the page "remember" what the user entered. |
|
|
|
Features/technologies discussed: |
|
|
|
• The Request object. |
|
• The SQL Where clause. |
|
|
|
What You'll Build |
|
|
|
In the previous tutorial, you created a database, added data to it, and then used the WebGrid |
|
helper to display the data. In this tutorial,you'll add a search box that lets you find movies of a |
|
specific genre or whose title contains whatever word you enter. (For example, you'll be able to |
|
find all movies whose genre is "Action" or whose title contains "Harry" or "Adventure.") |
|
|
|
When you're done with this tutorial, you'll have a page like this one: |
|
|
|
The listing part of the page is the same as in the last tutorial — a grid. The difference will be that |
|
the grid will show only the movies that you searched for. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
56 |
|
|
|
|
|
About HTML Forms |
|
|
|
(If you've got experience with creating HTML forms and with the difference between GET and |
|
POST, you can skip this section.) |
|
|
|
A form has user input elements — text boxes, buttons, radio buttons, check boxes, drop-down |
|
lists, and so on. Users fill in these controls or make selections and then submit the form by clicking |
|
a button. |
|
|
|
The basic HTML syntax of a form is illustrated by this example: |
|
|
|
<form method="post"> |
|
<input type="text" name="name" value="" /> |
|
<br/> |
|
<input type="submit" name="submit" value="Submit" /> |
|
</form> |
|
|
|
When this markup runs in a page, it creates a simple form that looks like this illustration: |
|
|
|
The <form> element encloses HTML elements to be submitted. (An easy mistake to make is to add |
|
elements to the page but then forget to put them inside a <form> element. In that case, nothing is |
|
submitted.) The method attribute tells the browser how to submit the user input. You set this to |
|
post if you're performing an update on the server or to get if you're just fetching data from the |
|
server. |
|
|
|
GET, POST, and HTTP Verb Safety |
|
|
|
HTTP, the protocol that browsers and servers use to exchange information, is remarkably simple |
|
in its basic operations. Browsers use only a few verbs to make requests to servers. When you |
|
write code for the web, it's helpful to understand these verbs and how the browser and server |
|
use them. Far and away the most commonly used verbs are these: |
|
|
|
GET. The browser uses this verb to fetch something from the server. For example, when you type a |
|
URL into your browser, the browser performs a GET operation to request the page you want. If the |
|
page includes graphics, the browser performs additional GET operations to get the images. If the |
|
GET operation has to pass information to the server, the information is passed as part of the URL |
|
in the query string. |
|
|
|
POST. The browser sends a POST request in order to submit data to be added or changed on the |
|
server. For example, the POST verb is used to create records in a database or change existing ones. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
57 |
|
|
|
|
|
Most of the time, when you fill in a form and click the submit button, the browser performs a POST |
|
operation. In a POST operation, the data being passed to the server is in the body of the page. |
|
|
|
An important distinction between these verbs is that a GET operation is not supposed to change |
|
anything on the server — or to put it in a slightly more abstract way, a GET operation does not |
|
result in a change in state on the server. You can perform a GET operation on the same resources |
|
as many times as you like, and those resources don't change. (A GET operation is often said to be |
|
"safe," or to use a technical term, is idempotent.) In contrast, of course, a POST request changes |
|
something on the server each time you perform the operation. |
|
|
|
Two examples will help illustrate this distinction. When you perform a search using an engine like |
|
Bing or Google, you fill in a form that consists of one text box, and then you click the search |
|
button. The browser performs a GET operation, with the value you entered into the box passed as |
|
part of the URL. Using a GET operation for this type of form is fine, because a search operation |
|
doesn't change any resources on the server, it just fetches information. |
|
|
|
Now consider the process of ordering something online. You fill in the order details and then click |
|
the submit button. This operation will be a POST request, because the operation will result in |
|
changes on the server, such as a new order record, a change in your account information, and |
|
perhaps many other changes. Unlike the GET operation, you cannot repeat your POST request — if |
|
you did, each time you resubmitted the request, you'd generate a new order on the server. (In |
|
cases like this, websites will often warn you not to click a submit button more than once, or will |
|
disable the submit button so that you don't resubmit the form accidentally.) |
|
|
|
In the course of this tutorial, you'll use both a GET operation and a POST operation to work with |
|
HTML forms. We'll explain in each case why the verb you use is the appropriate one. |
|
|
|
(To learn more about HTTP verbs, see the Method Definitions article on the W3C site.) |
|
|
|
Most user input elements are HTML <input> elements. They look like <input type="type" |
|
name="name">, where type indicates the kind of user input control you want. These elements are |
|
the common ones: |
|
|
|
• Text box: <input type="text"> |
|
• Check box: <input type="check"> |
|
• Radio button: <input type="radio"> |
|
• Button: <input type="button"> |
|
• |
|
|
|
Submit button: <input type="submit"> |
|
|
|
You can also use the <textarea> element to create a multiline text box and the <select> element |
|
to create a drop-down list or scrollable list. (For more about HTML form elements, see HTML |
|
Forms and Input on the W3Schools site.) |
|
|
|
The name attribute is very important, because the name is how you'll get the value of the element |
|
later, as you'll see shortly. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
58 |
|
|
|
The interesting part is what you, the page developer, do with the user's input. There's no built-in |
|
behavior associated with these elements. Instead, you have to get the values that the user has |
|
entered or selected and do something with them. That's what you'll learn in this tutorial. |
|
|
|
HTML5 and Input Forms |
|
|
|
As you might know, HTML is in transition and the latest version (HTML5) includes support for |
|
more intuitive ways for users to enter information. For example, in HTML5, you (the page |
|
developer) can tell the page that you want the user to enter a date. The browser can then |
|
automatically display a calendar rather than requiring the user to enter a date manually. |
|
However, HTML5 is new and is not supported in all browsers yet. |
|
|
|
ASP.NET Web Pages supports HTML5 input to the extent that the user's browser does. For an idea |
|
of the new attributes for the <input> element in HTML5, see HTML <input> type Attribute on the |
|
W3Schools site. |
|
|
|
Creating the Form |
|
|
|
In WebMatrix, in the Files workspace, open the Movies.cshtml page. |
|
|
|
After the closing </h1> tag and before the opening <div> tag of the grid.GetHtml call, add the |
|
following markup: |
|
|
|
<form method="get"> |
|
<div> |
|
<label for="searchGenre">Genre to look for:</label> |
|
<input type="text" name="searchGenre" value="" /> |
|
<input type="Submit" value="Search Genre" /><br/> |
|
(Leave blank to list all movies.)<br/> |
|
</div> |
|
</form> |
|
|
|
This markup creates a form that has a text box named searchGenre and a submit button. The text |
|
box and submit button are enclosed in a <form> element whose method attribute is set to get. |
|
(Remember that if you don't put the text box and submit button inside a <form> element, nothing |
|
will be submitted when you click the button.) You use the GET verb here because you're creating a |
|
form that does not make any changes on the server — it just results in a search. (In the previous |
|
tutorial, you used a post method, which is how you submit changes to the server. You'll see that |
|
in the next tutorial again.) |
|
|
|
Run the page. Although you haven't defined any behavior for the form, you can see what it looks |
|
like: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
59 |
|
|
|
Enter a value into the text box, like "Comedy." Then click Search Genre. |
|
|
|
Take note of the URL of the page. Because you set the <form> element's method attribute to get, |
|
the value you entered is now part of the query string in the URL, like this: |
|
|
|
http://localhost:45661/Movies.cshtml?searchGenre=Comedy |
|
|
|
Reading Form Values |
|
|
|
The page already contains some code that gets database data and displays the results in a grid. |
|
Now you have to add some code that reads the value of the text box so you can run a SQL query |
|
that includes the search term. |
|
|
|
Because you set the form's method to get, you can read the value that was entered into the text |
|
box by using code like the following: |
|
|
|
var searchTerm = Request.QueryString["searchGenre"]; |
|
|
|
The Request.QueryString object (the QueryString property of the Request object) includes the |
|
values of elements that were submitted as part of the GET operation. The Request.QueryString |
|
property contains a collection (a list) of the values that are submitted in the form. To get any |
|
individual value, you specify the name of the element that you want. That's why you have to have |
|
a name attribute on the <input> element (searchTerm) that creates the text box. (For more about |
|
the Request object, see the sidebar later.) |
|
|
|
It's simple enough to read the value of the text box. But if the user didn't enter anything at all in |
|
the text box but clicked Search anyway, you can ignore that click, since there's nothing to search. |
|
|
|
The following code is an example that shows how to implement these conditions. (You don't have |
|
to add this code yet; you'll do that in a moment.) |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
60 |
|
|
|
|
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
// Do something here |
|
} |
|
|
|
The test breaks down in this way: |
|
|
|
• Get the value of Request.QueryString["searchGenre"], namely the value that was entered |
|
|
|
• |
|
|
|
into the <input> element named searchGenre. |
|
Find out if it's empty by using the IsEmpty method.This method is the standard way to |
|
determine whether something (for example, a form element) contains a value. But really, |
|
you care only if it's not empty, therefore ... |
|
|
|
• Add the ! operator in front of the IsEmpty test. (The ! operator means logical NOT). |
|
|
|
In plain English, the entire if condition translates into the following: If the form's searchGenre |
|
element is not empty, then ... |
|
|
|
This block sets the stage for creating a query that uses the search term. You'll do that in the next |
|
section. |
|
|
|
The Request Object |
|
|
|
The Request object contains all the information that the browser sends to your application when a |
|
page is requested or submitted. This object includes any information that the user provides, like |
|
text box values or a file to upload. It also includes all sorts of additional information, like cookies, |
|
values in the URL query string (if any), the file path of the page that is running, the type of |
|
browser that the user is using, the list of languages that are set in the browser, and much more. |
|
|
|
The Request object is a collection (list) of values. You get an individual value out of the collection |
|
by specifying its name: |
|
|
|
var someValue = Request["name"]; |
|
|
|
The Request object actually exposes several subsets. For example: |
|
|
|
Request.Form gives you values from elements inside the submitted <form> element if the request |
|
is a POST request. |
|
|
|
Request.QueryString gives you just the values in the URL's query string. (In a URL like |
|
http://mysite/myapp/page?searchGenre=action&page=2, the ?searchGenre=action&page=2 section |
|
of the URL is the query string.) |
|
|
|
Request.Cookies collection gives you access to cookies that the browser has sent. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
61 |
|
|
|
To get a value that you know is in the submitted form, you can use Request["name"]. |
|
Alternatively, you can use the more specific versions Request.Form["name"] (for POST requests) or |
|
Request.QueryString["name"] (for GET requests). Of course, name is the name of the item to get. |
|
|
|
The name of the item you want to get has to be unique within the collection you're using. That's |
|
why the Request object provides the subsets like Request.Form and Request.QueryString. Suppose |
|
that your page contains a form element named userName and also contains a cookie named |
|
userName. If you get Request["userName"], it's ambiguous whether you want the form value or the |
|
cookie. However, if you get Request.Form["userName"] or Request.Cookie["userName"], you're |
|
being explicit about which value to get. |
|
|
|
It's a good practice to be specific and use the subset of Request that you're interested in, like |
|
Request.Form or Request.QueryString. For the simple pages that you're creating in this tutorial, it |
|
probably doesn't really make any difference. However, as you create more complex pages, using |
|
the explicit version Request.Form or Request.QueryString can help you avoid problems that can |
|
arise when the page contains a form (or multiple forms), cookies, query string values, and so on. |
|
|
|
Creating a Query by Using a Search Term |
|
|
|
Now that you know how to get the search term that the user entered, you can create a query that |
|
uses it. Remember that to get all the movie items out of the database, you're using a SQL query |
|
that looks like this statement: |
|
|
|
SELECT * FROM Movies |
|
|
|
To get only certain movies, you have to use a query that includes a Where clause. This clause lets |
|
you set a condition on which rows are returned by the query. Here's an example: |
|
|
|
SELECT * FROM Movies WHERE Genre = 'Action' |
|
|
|
The basic format is WHERE column = value. You can use different operators besides just =, like > |
|
(greater than), < (less than), <> (not equal to), <= (less than or equal to), etc., depending on what |
|
you're looking for. |
|
|
|
In case you're wondering, SQL statements are not case sensitive — SELECT is the same as Select |
|
(or even select). However, people often capitalize keywords in a SQL statement, like SELECT and |
|
WHERE, to make it easier to read. |
|
|
|
Passing the search term as a parameter |
|
|
|
Searching for a specific genre is easy enough (WHERE Genre = 'Action'), but you want to be able |
|
to search for any genre that the user enters. To do that, you create as SQL query that includes a |
|
placeholder for the value to search. It will look like this command: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
62 |
|
|
|
SELECT * FROM Movies WHERE Genre = @0 |
|
|
|
The placeholder is the @ character followed by zero. As you might guess, a query can contain |
|
multiple placeholders, and they'd be named @0, @1, @2, etc. |
|
|
|
To set up the query and actually pass it the value, you use the code like the following: |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
selectedData = db.Query(selectCommand, Request.QueryString["searchGenre"]); |
|
|
|
This code is similar to what you've already done to display data in the grid. The only differences |
|
are: |
|
|
|
• The query contains a placeholder (WHERE Genre = @0"). |
|
• The query is put into a variable (selectCommand); before, you passed the query directly to |
|
|
|
the db.Query method. |
|
|
|
• When you call the db.Query method, you pass both the query and the value to use for the |
|
placeholder. (If the query had multiple placeholders, you'd pass them all as separate |
|
values to the method.) |
|
|
|
If you put all these elements together, you get the following code: |
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
searchTerm = Request.QueryString["searchGenre"]; |
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
selectedData = db.Query(selectCommand, searchTerm); |
|
} |
|
|
|
Important! Using placeholders (like @0) to pass values to a SQL command is extremely |
|
important for security. The way you see it here, with placeholders for variable data, is the |
|
only way you should construct SQL commands. |
|
|
|
Never construct a SQL statement by putting together (concatenating) literal text and |
|
values you get from the user. Concatenating user input into a SQL statement opens your |
|
site to a SQL injection attack where a malicious user submits values to your page that hack |
|
your database. (You can read more in the article SQL Injection the MSDN website.) |
|
|
|
Updating the Movies Page with Search Code |
|
|
|
Now you can update the code in the Movies.cshtml file. To begin, replace the code in the code |
|
block at the top of the page with this code: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
63 |
|
|
|
|
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
var selectCommand = "SELECT * FROM Movies"; |
|
var searchTerm = ""; |
|
|
|
The difference here is that you've put the query into the selectCommand variable, which you'll pass |
|
to db.Query later. Putting the SQL statement into a variable lets you change the statement, which |
|
is what you'll do to perform the search. |
|
|
|
You've also removed these two lines, which you'll put back in later: |
|
|
|
var selectedData = db.Query("SELECT * FROM Movies"); |
|
var grid = new WebGrid(source: selectedData, rowsPerPage: 3); |
|
|
|
You don't want to run the query yet (that is, call db.Query) and you don't want to initialize the |
|
WebGrid helper yet either. You'll do those things after you've figured out which SQL statement has |
|
to run. |
|
|
|
After this rewritten block, you can add the new logic for handling the search. The completed code |
|
will look like the following. Update the code in your page so it matches this example: |
|
|
|
@{ |
|
var db = Database.Open("WebPagesMovies") ; |
|
var selectCommand = "SELECT * FROM Movies"; |
|
var searchTerm = ""; |
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
searchTerm = Request.QueryString["searchGenre"]; |
|
} |
|
|
|
var selectedData = db.Query(selectCommand, searchTerm); |
|
var grid = new WebGrid(source: selectedData, defaultSort: "Genre", |
|
rowsPerPage:3); |
|
} |
|
|
|
The page now works like this. Every time the page runs, the code opens the database and the |
|
selectCommand variable is set to the SQL statement that gets all the records from the Movies table. |
|
The code also initializes the searchTerm variable. |
|
|
|
However, if the current request includes a value for the searchGenre element, the code sets |
|
selectCommand to a different query — namely, to one that includes the Where clause to search for a |
|
genre. It also sets searchTerm to whatever was passed for the search box (which might be |
|
nothing). |
|
|
|
Regardless of which SQL statement is in selectCommand, the code then calls db.Query to run the |
|
query, passing it whatever is in searchTerm. If there's nothing in searchTerm, it doesn't matter, |
|
because in that case there's no parameter to pass the value to selectCommand anyway. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
64 |
|
|
|
|
|
|
|
Finally, the code initializes the WebGrid helper by using the query results, just like before. |
|
|
|
You can see that by putting the SQL statement and the search term into variables, you've added |
|
flexibility to the code. As you'll see later in this tutorial, you can use this basic framework and |
|
keep adding logic for different types of searches. |
|
|
|
Testing the Search-by-Genre Feature |
|
|
|
In WebMatrix, run the Movies.cshtml page. You see the page with the text box for genre. |
|
|
|
Enter a genre that you've entered for one of your test records, then click Search. This time you |
|
see a listing of just the movies that match that genre: |
|
|
|
Enter a different genre and search again. Try entering the genre by using all lowercase or all |
|
uppercase letters so that you can see that the search is not case sensitive. |
|
|
|
"Remembering" What the User Entered |
|
|
|
You might have noticed that after you entered a genre and clicked Search Genre, you saw a listing |
|
for that genre. However, the search text box was empty — in other words, it didn't remember |
|
what you'd entered. |
|
|
|
It's important to understand why this behavior occurs. When you submit a page, the browser |
|
sends a request to the web server. When ASP.NET gets the request, it creates a brand-new |
|
instance of the page, runs the code in it, and then renders the page to the browser again. In |
|
effect, though, the page doesn't know that you were just working with a previous version of itself. |
|
All it knows is that it got a request that had some form data in it. |
|
|
|
Every time you request a page — whether for the first time or by submitting it — you're getting a |
|
new page. The web server has no memory of your last request. Neither does ASP.NET, and neither |
|
does the browser. The only connection between these separate instances of the page is any data |
|
that you transmit between them. If you submit a page, for example, the new page instance can |
|
get the form data that was sent by the earlier instance. (Another way to pass data between pages |
|
is to use cookies.) |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
65 |
|
|
|
|
|
A formal way to describe this situation is to say that web pages are stateless. Web servers and the |
|
pages themselves and the elements in the page do not maintain any information about the |
|
previous state of a page. The web was designed this way because maintaining state for individual |
|
requests would quickly exhaust the resources of web servers, which often handle thousands, |
|
maybe even hundreds of thousands, of requests per second. |
|
|
|
So that's why the text box was empty. After you submitted the page, ASP.NET created a new |
|
instance of the page and ran through the code and markup. There was nothing in that code that |
|
told ASP.NET to put a value into the text box. So ASP.NET didn't do anything, and the text box was |
|
rendered without a value in it. |
|
|
|
There's actually an easy way to get around this issue. The genre that you entered into the text box |
|
is available to you in code — it's in Request.QueryString["searchGenre"]. |
|
|
|
Update the markup for the text box so that the value attribute gets its value from searchTerm, like |
|
this example: |
|
|
|
<input type="text" name="searchGenre" value="@Request.QueryString["searchGenre"]" |
|
/> |
|
|
|
In this page, you could have also set the value attribute to the searchTerm variable, since that |
|
variable also contains the genre you entered. But using the Request object to set the value |
|
attribute as shown here is the standard way to accomplish this task. (Assuming you even want to |
|
do this — in some situations, you might want to render the page without values in the fields. It all |
|
depends on what's going on with your app.) |
|
|
|
Note You can't "remember" the value of a text box that's used for passwords. It would be |
|
a security hole to allow people to fill in a password field by using code. |
|
|
|
Run the page again, enter a genre, and click Search Genre. This time not only do you see the |
|
results of the search, but the text box remembers what you entered last time: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
66 |
|
|
|
|
|
Searching for Any Word in the Title |
|
|
|
You can now search for any genre, but you might also want to search for a title. It's hard to get a |
|
title exactly right when you search, so instead you can search for a word that appears anywhere |
|
inside a title. To do that in SQL, you use the LIKE operator and syntax like the following: |
|
|
|
SELECT * FROM Movies WHERE Title LIKE '%adventure%' |
|
|
|
This command gets all the movies whose titles contain "adventure". When you use the LIKE |
|
operator, you include the wildcard character % as part of the search term. The search LIKE |
|
'adventure%' means "starting with 'adventure'". (Technically, it means "The string 'adventure' |
|
followed by anything.") Similarly, the search term LIKE '%adventure' means "anything followed |
|
by the string 'adventure'", which is another way to say "ending with 'adventure'". |
|
|
|
The search term LIKE '%adventure%' therefore means "with 'adventure' anywhere in the title." |
|
(Technically, "anything in the title, followed by 'adventure', followed by anything.") |
|
|
|
Inside the <form> element, add the following markup right under the closing </div> tag for the |
|
genre search (just before the closing </form> element): |
|
|
|
<div> |
|
<label for="SearchTitle">Movie title contains the following:</label> |
|
<input type="text" name="searchTitle" |
|
value="@Request.QueryString["searchTitle"]" /> |
|
<input type="Submit" value="Search Title" /><br/> |
|
</div> |
|
|
|
The code to handle this search is similar to the code for the genre search, except that you have to |
|
assemble the LIKE search. Inside the code block at the top of the page, add this if block just after |
|
the if block for the genre search: |
|
|
|
if(!Request.QueryString["searchTitle"].IsEmpty() ) { |
|
selectCommand = "SELECT * FROM Movies WHERE Title LIKE @0"; |
|
searchTerm = "%" + Request["searchTitle"] + "%"; |
|
} |
|
|
|
This code uses the same logic you saw earlier, except that the search uses a LIKE operator and the |
|
code puts "%" before and after the search term. |
|
|
|
Notice how it was easy to add another search to the page. All you had to do was: |
|
|
|
• Create an if block that tested to see whether the relevant search box had a value. |
|
• |
|
• |
|
|
|
Set the selectCommand variable to a new SQL statement. |
|
Set the searchTerm variable to the value to pass to the query. |
|
|
|
Here's the complete code block, which contains the new logic for a title search: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
67 |
|
|
|
@{ |
|
var db = Database.Open("WebPagesMovies") ; |
|
var selectCommand = "SELECT * FROM Movies"; |
|
var searchTerm = ""; |
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
searchTerm = Request.QueryString["searchGenre"]; |
|
} |
|
|
|
if(!Request.QueryString["searchTitle"].IsEmpty() ) { |
|
selectCommand = "SELECT * FROM Movies WHERE Title LIKE @0"; |
|
searchTerm = "%" + Request["searchTitle"] + "%"; |
|
} |
|
|
|
var selectedData = db.Query(selectCommand, searchTerm); |
|
var grid = new WebGrid(source: selectedData, defaultSort: "Genre", |
|
rowsPerPage:8); |
|
} |
|
|
|
Here's a summary of what this code does: |
|
|
|
• The variables searchTerm and selectCommand are initialized at the top. You're going to set |
|
these variables to the appropriate search term (if any) and appropriate SQL command |
|
based on what the user does in the page. The default search is the simple case of getting |
|
all the movies from the database. |
|
In the tests for searchGenre and searchTitle, the code sets searchTerm to the value you |
|
want to search for. Those code blocks also set selectCommand to an appropriate SQL |
|
command for that search. |
|
|
|
• |
|
|
|
• The db.Query method is invoked only once, using whatever SQL command is in |
|
|
|
selectedCommand and whatever value is in searchTerm. If there is no search term (no genre |
|
and no title word), the value of searchTerm is an empty string. However, that doesn't |
|
matter, because in that case the query doesn't require a parameter. |
|
|
|
Testing the Title Search Feature |
|
|
|
Now you can test your completed search page. Run Movies.cshtml. |
|
|
|
Enter a genre and click Search Genre. The grid displays movies of that genre, like before. |
|
|
|
Enter a title word and click Search Title. The grid displays movies that have that word in the title. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
68 |
|
|
|
|
|
|
|
|
|
Leave both text boxes blank and click either button. The grid displays all the movies. |
|
|
|
Combining the Queries |
|
|
|
You might notice that the searches you can perform are exclusive. You can't search the title and |
|
the genre at the same time, even if both search boxes have values in them. For example, you can't |
|
search for all action movies whose title contains "Adventure". (As the page is coded now, if you |
|
enter values for both genre and title, the title search gets precedence.) To create a search that |
|
combines the conditions,you would have to create a SQL query that has syntax like the following: |
|
|
|
SELECT * FROM Movies WHERE Genre = @0 AND Title LIKE @1 |
|
|
|
And you'd have to run the query by using a statement like the following (roughly speaking): |
|
|
|
var selectedData = db.Query(selectCommand, searchGenre, searchTitle); |
|
|
|
Creating logic to allow many permutations of search criteria can get a bit involved, as you can see. |
|
Therefore, we'll stop here. |
|
|
|
Coming Up Next |
|
|
|
In the next tutorial, you'll create a page that uses a form to let users add movies to the database. |
|
|
|
Additional Resources |
|
|
|
Introduction to ASP.NET Web Programming Using the Razor Syntax |
|
• |
|
SQL WHERE Clause on the W3Schools site |
|
• |
|
• Method Definitions article on the W3C site |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 4: HTML Form Basics |
|
|
|
69 |
|
|
|
|
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
This tutorial shows you how to create an entry form and then enter the data that you get from |
|
the form into a database table when you use ASP.NET Web Pages (Razor). |
|
|
|
What you'll learn: |
|
|
|
• More about how to process entry forms. |
|
• How to add (insert) data in a database. |
|
• How to make sure that users have entered a required value in a form (how to validate |
|
|
|
user input). |
|
|
|
• How to display validation errors. |
|
• How to jump to another page from the current page. |
|
|
|
Features/technologies discussed: |
|
|
|
• The Database.Execute method. |
|
• The SQL Insert Into statement |
|
• The Validation helper. |
|
• The Response.Redirect method. |
|
|
|
What You'll Build |
|
|
|
In the tutorial earlier that showed you how to create a database, you entered database data by |
|
editing the database directly in WebMatrix, working in the Database workspace. In most apps, |
|
that's not a practical way to put data into the database, though. So in this tutorial, you'll create a |
|
web-based interface that lets you or anyone enter data and save it to the database. |
|
|
|
You'll create a page where you can enter new movies. The page will contain an entry form that |
|
has fields (text boxes) where you can enter a movie title, genre, and year.The page will look like |
|
this page: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
70 |
|
|
|
|
|
The text boxes will be HTML <input> elements that will look like this markup: |
|
|
|
<input type="text" name="genre" value="" /> |
|
|
|
Creating the Basic Entry Form |
|
|
|
Create a page named AddMovie.cshtml. |
|
|
|
Replace what's in the file with the following markup. Overwrite everything; you'll add a code |
|
block at the top shortly. |
|
|
|
<!DOCTYPE html> |
|
<html> |
|
<head> |
|
<meta charset="utf-8" /> |
|
<title>Add a Movie</title> |
|
</head> |
|
<body> |
|
<h1>Add a Movie</h1> |
|
<form method="post"> |
|
<fieldset> |
|
<legend>Movie Information</legend> |
|
<p><label for="title">Title:</label> |
|
<input type="text" name="title" value="@Request.Form["title"]" /> |
|
|
|
<p><label for="genre">Genre:</label> |
|
<input type="text" name="genre" value="@Request.Form["genre"]" /> |
|
|
|
<p><label for="year">Year:</label> |
|
<input type="text" name="year" value="@Request.Form["year"]" /> |
|
|
|
<p><input type="submit" name="buttonSubmit" value="Add Movie" /></p> |
|
</fieldset> |
|
</form> |
|
</body> |
|
</html> |
|
|
|
This example shows is typical HTML for creating a form. It uses <input> elements for the text |
|
boxes and for the submit button. The captions for the text boxes are created by using standard |
|
<label> elements. The <fieldset> and <legend> elements put a nice box around the form. |
|
|
|
Notice that in this page, the <form> element uses post as the value for the method attribute. In the |
|
previous tutorial, you created a form that used the get method. That was correct, because |
|
although the form submitted values to the server, the request did not make any changes. All it did |
|
was fetch data in different ways. However, in this page you will make changes—you're going to |
|
add new database records. Therefore, this form should use the post method. (For more about the |
|
difference between GET and POST operations, see the GET, POST, and HTTP Verb Safety sidebar in |
|
the previous tutorial.) |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
71 |
|
|
|
|
|
|
|
|
|
Note that each text box has a name element (title, genre, year). As you saw in the previous |
|
tutorial, these names are important because you must have those names so you can get the |
|
user's input later. You can use any names. It's helpful to use meaningful names that help you |
|
remember what data you're working with. |
|
|
|
The value attribute of each <input> element contains a bit of Razor code (for example, |
|
Request.Form["title"]). You learned a version of this trick in the previous tutorial to preserve the |
|
value entered into the text box (if any) after the form has been submitted. |
|
|
|
Getting the Form Values |
|
|
|
Next, you add code that processes the form. In outline, you'll do the following: |
|
|
|
1. Check whether the page is being posted (was submitted). You want to your code to run |
|
|
|
only when users have clicked the button, not when the page first runs. |
|
|
|
2. Get the values that the user entered into the text boxes. In this case, because the form is |
|
|
|
using the POST verb, you get the form values from the Request.Form collection. |
|
Insert the values as a new record in the Movies database table. |
|
|
|
3. |
|
|
|
At the top of the file, add the following code: |
|
|
|
@{ |
|
var title = ""; |
|
var genre = ""; |
|
var year = ""; |
|
|
|
if(IsPost){ |
|
title = Request.Form["title"]; |
|
genre = Request.Form["genre"]; |
|
year = Request.Form["year"]; |
|
} |
|
} |
|
|
|
The first few lines create variables (title, genre, and year) to hold the values from the text |
|
boxes.The line if(IsPost) makes sure that the variables are set only when users click the Add |
|
Movie button — that is, when the form has been posted. |
|
|
|
As you saw in an earlier tutorial, you get the value of a text box by using an expression like |
|
Request.Form["name"], where name is the name of the <input> element. |
|
|
|
The names of the variables (title, genre, and year) are arbitrary. Like the names that you assign |
|
to <input> elements, you can call them anything you like. (The names of the variables don't have |
|
to match the name attributes of <input> elements on the form.) But as with the <input> |
|
elements, it's a good idea to use variable names that reflect the data that they contain. When you |
|
write code, consistent names make it easier for you to remember what data you're working with. |
|
|
|
Introducing ASP.NET Web Pages 2 |
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|
Tutorial 5: Entering Database Data by Using Forms |
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|
72 |
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|
|
Adding Data to the Database |
|
|
|
In the code block you just added, just inside the closing brace ( } ) of the if block (not just inside |
|
the code block), add the following code: |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
var insertCommand = "INSERT INTO Movies (Title, Genre, Year) VALUES(@0, @1, @2)"; |
|
db.Execute(insertCommand, title, genre, year); |
|
|
|
This example is similar to the code you used in a previous tutorial to fetch and display data. The |
|
line that starts with db = opens the database, like before, and the next line defines a SQL |
|
statement, again as you saw before. However, this time it defines a SQL Insert Into statement. |
|
The following example shows the general syntax of the Insert Into statement: |
|
|
|
INSERT INTO table (column1, column2, column3, ...) VALUES (value1, value2, |
|
value3, ...) |
|
|
|
In other words, you specify the table to insert into, then list the columns to insert into, and then |
|
list the values to insert.(As noted before, SQL is not case sensitive but some people capitalize the |
|
keywords to make it easier to read the command.) |
|
|
|
The columns that you're inserting into are already listed in the command — (Title, Genre, |
|
Year). The interesting part is how you get the values from the text boxes into the VALUES part of |
|
the command. Instead of actual values, you see @0, @1, and @2, which are of course placeholders. |
|
When you run the command (on the db.Execute line), you pass the values that you got from the |
|
text boxes. |
|
|
|
Important!Remember that the only way you should ever include data entered online by a |
|
user in a SQL statement is to use placeholders, as you see here (VALUES(@0, @1, @2)). If |
|
you concatenate user input into a SQL statement, you open yourself to a SQL injection |
|
attack, as explained in HTML Form Basics (the previous tutorial). |
|
|
|
Still inside the if block, add the following line after the db.Execute line: |
|
|
|
Response.Redirect("~/Movies"); |
|
|
|
After the new movie has been inserted into the database, this line jumps you (redirects) to the |
|
Movies page so you can see the movie you just entered. The ~ operator means "root of the |
|
website." (The ~ operator works only in ASP.NET pages, not in HTML generally.) |
|
|
|
The complete code block looks like this example: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
73 |
|
|
|
|
|
@{ |
|
var title = ""; |
|
var genre = ""; |
|
var year = ""; |
|
|
|
if(IsPost){ |
|
title = Request.Form["title"]; |
|
genre = Request.Form["genre"]; |
|
year = Request.Form["year"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
var insertCommand = "INSERT INTO Movies (Title, Genre, Year) " + |
|
"Values(@0, @1, @2)"; |
|
db.Execute(insertCommand, title, genre, year); |
|
Response.Redirect("~/Movies"); |
|
} |
|
} |
|
|
|
Testing the Insert Command (So Far) |
|
|
|
You're not done yet, but now is a good time to test. |
|
|
|
In the tree view of files in WebMatrix, right-click the AddMovie.cshtml page and then click Launch |
|
in browser. |
|
|
|
(If you end up with a different page in the browser, make sure that the URL is |
|
http://localhost:nnnnn/AddMovie), where nnnnn is the port number that you're using.) |
|
|
|
Did you get an error page? If so, read it carefully and make sure that the code looks exactly what |
|
was listed earlier. |
|
|
|
Enter a movie in the form — for example, use "Citizen Kane", "Drama", and "1941".(Or whatever.) |
|
Then click Add Movie. |
|
|
|
If all goes well, you're redirected to the Movies page. Make sure that your new movie is listed. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
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|
Tutorial 5: Entering Database Data by Using Forms |
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|
|
74 |
|
|
|
|
|
|
|
|
|
Validating User Input |
|
|
|
Go back to the AddMovie page, or run it again. Enter another movie, but this time, enter only the |
|
title — for example, enter "Singin' in the Rain". Then click Add Movie. |
|
|
|
You're redirected to the Movies page again. You can find the new movie, but it's incomplete. |
|
|
|
When you created the Movies table, you explicitly said that none of the fields could be null. Here |
|
you have an entry form for new movies, and you're leaving fields blank. That's an error. |
|
|
|
In this case, the database didn't actually raise (or throw) an error. You didn't supply a genre or |
|
year, so the code in the AddMovie page treated those values as so-called empty strings. When the |
|
SQL Insert Into command ran, the genre and year fields didn't have useful data in them, but |
|
they weren't null. |
|
|
|
Obviously, you don't want to let users enter half-empty movie information into the database. The |
|
solution is to validate the user's input. Initially, the validation will simply make sure that the user |
|
has entered a value for all of the fields (that is, that none of them contains an empty string). |
|
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|
Introducing ASP.NET Web Pages 2 |
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|
Tutorial 5: Entering Database Data by Using Forms |
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|
75 |
|
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|
|
|
|
|
Null and Empty Strings |
|
|
|
In programming, there's a distinction between different notions of "no value." In general, a value |
|
is null if it has never been set or initialized in any way. In contrast, a variable that expects |
|
character data (strings) can be set to an empty string. In that case, the value is not null; it's just |
|
been explicitly set to a string of characters whose length is zero. These two statements show the |
|
difference: |
|
|
|
var firstName; // Not set, so its value is null |
|
|
|
var firstName = ""; // Explicitly set to an empty string -- not null |
|
|
|
It's a little more complicated than that, but the important point is that null represents a sort of |
|
undetermined state. |
|
|
|
Now and then it's important to understand exactly when a value is null and when it's just an |
|
empty string. In the code for the AddMovie page, you get the values of the text boxes by using |
|
Request.Form["title"] and so on. When the page first runs (before you click the button), the |
|
value of Request.Form["title"] is null. But when you submit the form, Request.Form["title"] |
|
gets the value of the title text box. It's not obvious, but an empty text box is not null; it just has |
|
an empty string in it. So when the code runs in response to the button click, |
|
Request.Form["title"] has an empty string in it. |
|
|
|
Why is this distinction important? When you created the Movies table, you explicitly said that |
|
none of the fields could be null. But here you have an entry form for new movies, and you're |
|
leaving fields blank. You would reasonably expect the database to complain when you tried to |
|
save new movies that didn't have values for genre or year. But that's the point — even if you |
|
leave those text boxes blank, the values aren't null; they're empty strings. As a result, you're able |
|
to save new movies to the database with these columns empty — but not null! — values. |
|
Therefore, you have to make sure that users don't submit an empty string, which you can do by |
|
validating the user's input. |
|
|
|
The Validation Helper |
|
|
|
ASP.NET Web Pages includes a helper — the Validation helper — that you can use to make sure |
|
that users enter data that meets your requirements. The Validation helper is one of the helpers |
|
that's built in to ASP.NET Web Pages, so you don't have to install it as a package by using NuGet, |
|
the way you installed the Twitter helper in an earlier tutorial. |
|
|
|
To validate the user's input, you'll do the following: |
|
|
|
• Use code to specify that you want to require values in the text boxes on the page. |
|
• Put a test into the code so that the movie information is added to the database only if |
|
|
|
everything validates properly. |
|
|
|
• Add code into the markup to display error messages. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
76 |
|
|
|
In the code block in the AddMovie page, right up at the top before the variable declarations, add |
|
the following code: |
|
|
|
Validation.RequireField("title", "You must enter a title"); |
|
Validation.RequireField("genre", "Genre is required"); |
|
Validation.RequireField("year", "You haven't entered a year"); |
|
|
|
You call Validation.RequireField once for each field (<input> element) where you want to |
|
require an entry.You can also add a custom error message for each call, like you see here. (We |
|
varied the messages just to show that you can put anything you like there.) |
|
|
|
If there's a problem, you want to prevent the new movie information from being inserted into the |
|
database. In the if(IsPost) block, use && (logical AND) to add another condition that tests |
|
Validation.IsValid(). When you're done, the whole if(IsPost) block looks like this code: |
|
|
|
if(IsPost && Validation.IsValid()){ |
|
title = Request.Form["title"]; |
|
genre = Request.Form["genre"]; |
|
year = Request.Form["year"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
var insertCommand = "INSERT INTO Movies (Title, Genre, Year)" + |
|
" Values(@0, @1, @2)"; |
|
db.Execute(insertCommand, title, genre, year); |
|
Response.Redirect("~/Movies"); |
|
} |
|
|
|
If there's a validation error with any of the fields that you registered by using the Validation |
|
helper, the Validation.IsValid method returns false. And in that case, none of the code in that |
|
block will run, so no invalid movie entries will be inserted into the database. And of course you're |
|
not redirected to the Movies page. |
|
|
|
The complete code block, including the validation code, now looks like this example: |
|
|
|
@{ |
|
Validation.RequireField("title", "You must enter a title"); |
|
Validation.RequireField("genre", "Genre is required"); |
|
Validation.RequireField("year", "You haven't entered a year"); |
|
|
|
var title = ""; |
|
var genre = ""; |
|
var year = ""; |
|
|
|
if(IsPost && Validation.IsValid()){ |
|
title = Request.Form["title"]; |
|
genre = Request.Form["genre"]; |
|
year = Request.Form["year"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
var insertCommand = "INSERT INTO Movies (Title, Genre, Year) " + |
|
" Values(@0, @1, @2)"; |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
77 |
|
|
|
|
|
|
|
|
|
|
|
db.Execute(insertCommand, title, genre, year); |
|
Response.Redirect("~/Movies"); |
|
} |
|
} |
|
|
|
Displaying Validation Errors |
|
|
|
The last step is to display any error messages. You can display individual messages for each |
|
validation error, or you can display a summary, or both. For this tutorial, you'll do both so that |
|
you can see how it works. |
|
|
|
Next to each <input> element that you're validating, call the Html.ValidationMessage method and |
|
pass it the name of the <input> element you're validating. You put the Html.ValidationMessage |
|
method right where you want the error message to appear. When the page runs, the |
|
Html.ValidationMessage method renders a <span> element where the validation error will go. (If |
|
there's no error, the <span> element is rendered, but there's no text in it.) |
|
|
|
Change the markup in the page so that it includes an Html.ValidationMessage method for each of |
|
the three <input> elements on the page, like this example: |
|
|
|
<p><label for="title">Title:</label> |
|
<input type="text" name="title" value="@Request.Form["title"]" /> |
|
@Html.ValidationMessage("title") |
|
</p> |
|
|
|
<p><label for="genre">Genre:</label> |
|
<input type="text" name="genre" value="@Request.Form["genre"]" /> |
|
@Html.ValidationMessage("genre") |
|
</p> |
|
|
|
<p><label for="year">Year:</label> |
|
<input type="text" name="year" value="@Request.Form["year"]" /> |
|
@Html.ValidationMessage("year") |
|
</p> |
|
|
|
To see how the summary works, also add the following markup and code right after the <h1>Add a |
|
Movie</h1> element on the page: |
|
|
|
@Html.ValidationSummary() |
|
|
|
By default, the Html.ValidationSummary method displays all the validation messages in a list (a |
|
<ul> element that's inside a <div> element). As with the Html.ValidationMessage method, the |
|
markup for the validation summary is always rendered; if there are no errors, no list items are |
|
rendered. |
|
|
|
The summary can be an alternative way to display validation messages instead of by using the |
|
Html.ValidationMessage method to display each field-specific error. Or you can use both a |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
78 |
|
|
|
|
|
|
|
summary and the details. Or you can use the Html.ValidationSummary method to display a generic |
|
error and then use individual Html.ValidationMessage calls to display details. |
|
|
|
The complete page now looks like this example: |
|
|
|
@{ |
|
Validation.RequireField("title", "You must enter a title"); |
|
Validation.RequireField("genre", "Genre is required"); |
|
Validation.RequireField("year", "You haven't entered a year"); |
|
|
|
var title = ""; |
|
var genre = ""; |
|
var year = ""; |
|
|
|
if(IsPost && Validation.IsValid()){ |
|
title = Request.Form["title"]; |
|
genre = Request.Form["genre"]; |
|
year = Request.Form["year"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
var insertCommand = "INSERT INTO Movies (Title, Genre, Year) " + |
|
" Values(@0, @1, @2)"; |
|
db.Execute(insertCommand, title, genre, year); |
|
Response.Redirect("~/Movies"); |
|
} |
|
} |
|
|
|
<!DOCTYPE html> |
|
<html> |
|
<head> |
|
<meta charset="utf-8" /> |
|
<title>Add a Movie</title> |
|
</head> |
|
<body> |
|
<h1>Add a Movie</h1> |
|
@Html.ValidationSummary() |
|
<form method="post"> |
|
<fieldset> |
|
<legend>Movie Information</legend> |
|
<p><label for="title">Title:</label> |
|
<input type="text" name="title" value="@Request.Form["title"]" /> |
|
@Html.ValidationMessage("title") |
|
</p> |
|
|
|
<p><label for="genre">Genre:</label> |
|
<input type="text" name="genre" value="@Request.Form["genre"]" /> |
|
@Html.ValidationMessage("genre") |
|
</p> |
|
|
|
<p><label for="year">Year:</label> |
|
<input type="text" name="year" value="@Request.Form["year"]" /> |
|
@Html.ValidationMessage("year") |
|
</p> |
|
|
|
<p><input type="submit" name="buttonSubmit" value="Add Movie" /></p> |
|
</fieldset> |
|
</form> |
|
</body> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
79 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
</html> |
|
|
|
That's it. You can now test the page by adding a movie but leaving out one or more of the fields. |
|
When you do, you see the following error display: |
|
|
|
Styling the Validation Error Messages |
|
|
|
You can see that there are error messages, but they don't really stand out very well. There's an |
|
easy way to style the error messages, though. |
|
|
|
To style the individual error messages that are displayed by Html.ValidationMessage, create a CSS |
|
style class named field-validation-error. To define the look for the validation summary, create |
|
a CSS style class namedvalidation-summary-errors. |
|
|
|
To see how this technique works, add a <style> elementinside the <head> section of the page. |
|
Then define style classes named field-validation-error and validation-summary-errors that |
|
contain the following rules: |
|
|
|
<head> |
|
<meta charset="utf-8" /> |
|
<title>Add a Movie</title> |
|
<style type="text/css"> |
|
.field-validation-error { |
|
font-weight:bold; |
|
color:red; |
|
background-color:yellow; |
|
} |
|
.validation-summary-errors{ |
|
border:2px dashed red; |
|
color:red; |
|
background-color:yellow; |
|
font-weight:bold; |
|
margin:12px; |
|
} |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
80 |
|
|
|
|
|
</style> |
|
</head> |
|
|
|
Normally you'd probably put style information into a separate .css file, but for simplicity you can |
|
put them in the page for now. (Later in this tutorial set, you'll move the CSS rules to a separate |
|
.css file.) |
|
|
|
If there's a validation error, the Html.ValidationMessage method renders a <span> element that |
|
includes class="field-validation-error". By adding a style definition for that class, you can |
|
configure what the message looks like. If there are errors, the ValidationSummary method likewise |
|
dynamically renders the attribute class="validation-summary-errors". |
|
|
|
Run the page again and deliberately leave out a couple of the fields. The errors are now more |
|
noticeable. (In fact, they're overdone, but that's just to show what you can do.) |
|
|
|
Adding a Link to the Movies Page |
|
|
|
One final step is to make it convenient to get to the AddMovie page from the original movie |
|
listing. |
|
|
|
Open the Movies page again. After the closing </div> tag that follows the WebGrid helper, add the |
|
following markup: |
|
|
|
<p> |
|
<a href="~/AddMovie">Add a movie</a> |
|
</p> |
|
|
|
As you saw before, ASP.NET interprets the ~ operator as the root of the website. You don't have |
|
to use the ~ operator; you could use the markup <a href="./AddMovie">Add a movie</a> or some |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 5: Entering Database Data by Using Forms |
|
|
|
81 |
|
|
|
|
|
other way to define the path that HTML understands. But the ~ operator is a good general |
|
approach when you create links for Razor pages, because it makes the site more flexible — if you |
|
move the current page to a subfolder, the link will still go to the AddMovie page. (Remember that |
|
the ~ operator only works in .cshtml pages. ASP.NET understands it, but it's not standard HTML.) |
|
|
|
When you're done, run the Movies page. It will look like this page: |
|
|
|
Click the Add a movie link to make sure that it goes to the AddMovie page. |
|
|
|
Coming Up Next |
|
|
|
In the next tutorial, you'll learn how to let users edit data that's already in the database. |
|
|
|
Additional Resources |
|
|
|
• Complete Listing for AddMovie Page |
|
• |
|
• |
|
• Validating User Input in ASP.NET Web Pages Sites. More information about working with |
|
|
|
Introduction to ASP.NET Web Programming Using the Razor Syntax |
|
SQL INSERT INTO Statement on the W3Schools site |
|
|
|
the Validation helper. |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
This tutorial shows you how to update (change) an existing database entry when you use ASP.NET |
|
Web Pages (Razor). |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
82 |
|
|
|
|
|
|
|
What you'll learn: |
|
|
|
• How to select an individual record in the WebGrid helper. |
|
• How to read a single record from a database. |
|
• How to preload a form with values from the database record. |
|
• How to update an existing record in a database. |
|
• How to store information in the page without displaying it. |
|
• How to use a hidden field to store information. |
|
|
|
Features/technologies discussed: |
|
|
|
• The WebGrid helper. |
|
• The SQL Update command. |
|
• The Database.Execute method. |
|
• Hidden fields (<input type="hidden">). |
|
|
|
What You'll Build |
|
|
|
In the previous tutorial, you learned how to add a record to a database. Here, you'll learn how to |
|
display a record for editing.In the Movies page, you'll update the WebGrid helper so that it displays |
|
an Edit link next to each movie: |
|
|
|
When you click the Edit link, it takes you to a different page, where the movie information is |
|
already in a form: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
83 |
|
|
|
|
|
You can change any of the values. When you submit the changes, the code in the page updates |
|
the database and takes you back to the movie listing. |
|
|
|
This part of the process works almost exactly like the AddMovie.cshtml page you created in the |
|
previous tutorial, so much of this tutorial will be familiar. |
|
|
|
There are several ways you could implement a way to edit an individual movie. The approach |
|
shown was chosen because it's easy to implement and easy to understand. |
|
|
|
Adding an Edit Link to the Movie Listing |
|
|
|
To begin, you'll update the Movies page so that each movie listing also contains an Edit link. |
|
|
|
Open the Movies.cshtml file. |
|
|
|
In the body of the page, change the WebGrid markup by adding a column. Here's the modified |
|
markup: |
|
|
|
@grid.GetHtml( |
|
tableStyle: "grid", |
|
headerStyle: "head", |
|
alternatingRowStyle: "alt", |
|
columns: grid.Columns( |
|
grid.Column(format: @<a href="~/[email protected]">Edit</a>), |
|
grid.Column("Title"), |
|
grid.Column("Genre"), |
|
grid.Column("Year") |
|
) |
|
) |
|
|
|
The new column is this one: |
|
|
|
grid.Column(format: @<a href="~/[email protected])">Edit</a>) |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
84 |
|
|
|
|
|
The point of this column is to show a link (<a> element) whose text says "Edit". What we're after is |
|
to create a link that looks like the following when the page runs, with the id value different for |
|
each movie: |
|
|
|
http://localhost:43097/EditMovie?id=7 |
|
|
|
This link will invoke a page named EditMovie, and it will pass the query string ?id=7 to that page. |
|
|
|
The syntax for the new column might look a bit complex, but that's only because it puts together |
|
several elements. Each individual element is straightforward. If you concentrate on just the <a> |
|
element, you see this markup: |
|
|
|
<a href="~/[email protected])">Edit</a> |
|
|
|
Some background about how the grid works: the grid displays rows, one for each database |
|
record, and it displays columns for each field in the database record. While each grid row is being |
|
constructed,the item object contains the database record (item) for that row. This arrangement |
|
gives you a way in code to get at the data for that row. That's what you see here: the expression |
|
item.ID is getting the ID value of the current database item. You could get any of the database |
|
values (title, genre, or year) the same way by using item.Title, item.Genre, or item.Year. |
|
|
|
The expression "~/[email protected] combines the hard-coded part of the target URL |
|
(~/EditMovie?id=) with this dynamically derived ID. (You saw the ~ operator in the previous |
|
tutorial; it's an ASP.NET operator that reprethe current website root.) |
|
|
|
The result is that this part of the markup in the column simply produces something like the |
|
following markup at run time: |
|
|
|
href="/EditMovie?id=2" |
|
|
|
Naturally, the actual value of id will be different for each row. |
|
|
|
Creating a Custom Display for a Grid Column |
|
|
|
Now back to the grid column. The three columns you originally had in the grid displayed only data |
|
values (title, genre, and year). You specified this display by passing the name of the database |
|
column — for example, grid.Column("Title"). |
|
|
|
This new Edit link column is different. Instead of specifying a column name, you're passing a |
|
format parameter. This parameter lets you define markup that the WebGrid helper will render |
|
along with the item valueto display the column data as bold or green or in whatever format that |
|
you want. For example, if you wanted the title to appear bold, you could create a column like this |
|
example: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
85 |
|
|
|
grid.Column(format:@<strong>@item.Title</strong>) |
|
|
|
(The various @ characters you see in the format property mark the transition between markup and |
|
a code value.) |
|
|
|
Once you know about the format property, it's easier to understand how the new Edit link column |
|
is put together: |
|
|
|
grid.Column(format: @<a href="~/[email protected]">Edit</a>), |
|
|
|
The column consists only of the markup that renders the link, plus some information (the ID) |
|
that's extracted from the database record for the row. |
|
|
|
Named Parameters and Positional Parameters for a Method |
|
|
|
Many times when you've called a method and passed parameters to it, you've simply listed the |
|
parameter values separated by commas. Here are a couple of examples: |
|
|
|
db.Execute(insertCommand, title, genre, year) |
|
|
|
Validation.RequireField("title", "You must enter a title") |
|
|
|
We didn't mention the issue when you first saw this code, but in each case, you're passing |
|
parameters to the methods in a specific order — namely, the order in which the parameters are |
|
defined in that method. For db.Execute and Validation.RequireFields, if you mixed up the order |
|
of the values you pass, you'd get an error message when the page runs, or at least some strange |
|
results. Clearly, you have to know the order to pass the parameters in. (In WebMatrix, IntelliSense |
|
can help you learn figure out the name, type, and order of the parameters.) |
|
|
|
As an alternative to passing values in order, you can use named parameters. (Passing parameters |
|
in order is known as using positional parameters.) For named parameters, you explicitly include |
|
the name of the parameter when passing its value. You've used named parameters already a |
|
number of times in these tutorials. For example: |
|
|
|
var grid = new WebGrid(source: selectedData, defaultSort: "Genre", rowsPerPage:3) |
|
|
|
and |
|
|
|
@grid.GetHtml( |
|
tableStyle: "grid", |
|
headerStyle: "head", |
|
alternatingRowStyle: "alt", |
|
columns: grid.Columns( |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
86 |
|
|
|
grid.Column("Title"), |
|
grid.Column("Genre"), |
|
grid.Column("Year") |
|
) |
|
) |
|
|
|
Named parameters are handy for a couple of situations, especially when a method takes many |
|
parameters. One is when you want to pass only one or two parameters, but the values you want |
|
to pass are not among the first positions in the parameter list. Another situation is when you want |
|
to make your code more readable by passing the parameters in the order that makes the most |
|
sense to you. |
|
|
|
Obviously, to use named parameters, you have to know the names of the parameters. WebMatrix |
|
IntelliSense can show you the names, but it cannot currently fill them in for you. |
|
|
|
Creating the Edit Page |
|
|
|
Now you can create the EditMovie page. When users click the Edit link, they'll end up on this |
|
page. |
|
|
|
Create a page named EditMovie.cshtml and replace what's in the file with the following markup: |
|
|
|
<!DOCTYPE html> |
|
<html> |
|
<head> |
|
<meta charset="utf-8" /> |
|
<title>Edit a Movie</title> |
|
<style> |
|
.validation-summary-errors{ |
|
border:2px dashed red; |
|
color:red; |
|
font-weight:bold; |
|
margin:12px; |
|
} |
|
</style> |
|
</head> |
|
</head> |
|
<body> |
|
<h1>Edit a Movie</h1> |
|
@Html.ValidationSummary() |
|
<form method="post"> |
|
<fieldset> |
|
<legend>Movie Information</legend> |
|
|
|
<p><label for="title">Title:</label> |
|
<input type="text" name="title" value="@title" /></p> |
|
|
|
<p><label for="genre">Genre:</label> |
|
<input type="text" name="genre" value="@genre" /></p> |
|
|
|
<p><label for="year">Year:</label> |
|
<input type="text" name="year" value="@year" /></p> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
87 |
|
|
|
|
|
|
|
|
|
<input type="hidden" name="movieid" value="@movieId" /> |
|
|
|
<p><input type="submit" name="buttonSubmit" value="Submit Changes" /></p> |
|
</fieldset> |
|
</form> |
|
</body> |
|
</html> |
|
|
|
This markup and code is similar to what you have in the AddMovie page. There's a small |
|
difference in the text for the submit button. As with the AddMovie page, there's an |
|
Html.ValidationSummary call that will display validation errors if there are any. This time we're |
|
leaving out calls to Validation.Message, since errors will be displayed in the validation summary. |
|
As noted in the previous tutorial, you can use the validation summary and the individual error |
|
messages in various combinations. |
|
|
|
Notice again that the method attribute of the <form> element is set to post. As with the |
|
AddMovie.cshtml page, this page makes changes to the database. Therefore, this form should |
|
perform a POST operation. (For more about the difference between GET and POST operations, see |
|
the GET, POST, and HTTP Verb Safety sidebar in the tutorial on HTML forms.) |
|
|
|
As you saw in an earlier tutorial, the value attributes of the text boxes are being set with Razor |
|
code in order to preload them. This time, though, you're using variables like title and genre for |
|
that task instead of Request.Form["title"]: |
|
|
|
<input type="text" name="title" value="@title" /> |
|
|
|
As before, this markup will preload the text box values with the movie values. You'll see in a |
|
moment why it's handy to use variables this time instead of using the Request object. |
|
|
|
There's also a <input type="hidden"> element on this page. This element stores the movie ID |
|
without making it visible on the page. The ID is initially passed to the page by using a query string |
|
value (?id=7 or similar in the URL).By putting the ID value into a hidden field, you can make sure |
|
that it's available when the form is submitted, even if you no longer have access to the original |
|
URL that the page was invoked with. |
|
|
|
Unlike the AddMovie page, the code for the EditMovie page has two distinct functions. The first |
|
function is that when the page is displayed for the first time (and only then), the code gets the |
|
movie ID from the query string. The code then uses the ID to read the corresponding movie out of |
|
the database and display (preload) it in the text boxes. |
|
|
|
The second function is that when the user clicks the Submit Changes button, the code has to read |
|
the values of the text boxes and validate them. The code also has to update the database item |
|
with the new values. This technique is similar to adding a record, as you saw in AddMovie. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
88 |
|
|
|
|
|
|
|
Adding Code to Read a Single Movie |
|
|
|
To perform the first function, add this code to the top of the page: |
|
|
|
@{ |
|
var title = ""; |
|
var genre = ""; |
|
var year = ""; |
|
var movieId = ""; |
|
|
|
if(!IsPost){ |
|
if(!Request.QueryString["ID"].IsEmpty()){ |
|
movieId = Request.QueryString["ID"]; |
|
var db = Database.Open("WebPagesMovies"); |
|
var dbCommand = "SELECT * FROM Movies WHERE ID = @0"; |
|
var row = db.QuerySingle(dbCommand, movieId); |
|
title = row.Title; |
|
genre = row.Genre; |
|
year = row.Year; |
|
} |
|
else{ |
|
Validation.AddFormError("No movie was selected."); |
|
// If you are using a version of ASP.NET Web Pages 2 that's |
|
// earlier than the RC release, comment out the preceding |
|
// statement and uncomment the following one. |
|
//ModelState.AddFormError("No movie was selected."); |
|
} |
|
} |
|
} |
|
|
|
Most of this code is inside a block that starts if(!IsPost). The ! operator means "not,"so the |
|
expression means if this request is not a post submission, which is an indirect way of saying if this |
|
request is the first time that this page has been run. As noted earlier, this code should run only the |
|
first time the page runs. If you didn't enclose the code in if(!IsPost), it would run every time the |
|
page is invoked, whether the first time or in response to a button click. |
|
|
|
Notice that the code includes an else block this time. As we said when we introduced if blocks, |
|
sometimes you want to run alternative code if the condition you're testing isn't true. That's the |
|
case here. If the condition passes (that is, if the ID passed to the page is ok), you read a row from |
|
the database. However, if the condition doesn't pass, the else block runs and the code sets an |
|
error message. |
|
|
|
Validating a Value Passed to the Page |
|
|
|
The code uses Request.QueryString["id"] to get the ID that's passed to the page. The code |
|
makes sure that a value was actually passed for the ID. If no value was passed, the code sets a |
|
validation error. |
|
|
|
This code shows a different way to validate information. In the previous tutorial, you worked with |
|
the Validation helper. You registered fields to validate, and ASP.NET automatically did the |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
89 |
|
|
|
|
|
validation and displayed errors by using Html.ValidationMessage and Html.ValidationSummary. In |
|
this case, however, you're not really validating user input. Instead,you're validating a value that |
|
was passed to the page from elsewhere. The Validation helper doesn't do that for you. |
|
|
|
Therefore, you check the value yourself, by testing it |
|
withif(!Request.QueryString["ID"].IsEmpty()). If there's a problem, you can display the error by |
|
using Html.ValidationSummary, as you did with the Validation helper. To do that, you call |
|
Validation.AddFormError and pass it a message to display. Validation.AddFormError is a built-in |
|
method that lets you define custom messages that tie in with the validation system you're already |
|
familiar with. (Later in this tutorial we'll talk about how to make this validation process a little |
|
more robust.) |
|
|
|
Note If you're using a version of ASP.NET Web Pages 2 earlier than the RC release (for |
|
example, if you're using the Beta refresh release from February 2012), use |
|
ModelState.AddFormError instead of Validation.AddFormError. The AddFormError method |
|
was added to the Validation helper in the RC release. |
|
|
|
After making sure that there's an ID for the movie, the code reads the database, looking for only a |
|
single database item. (You probably have noticed the general pattern for database operations: |
|
open the database, define a SQL statement, and run the statement.) This time, the SQL Select |
|
statement includes WHERE ID = @0. Because the ID is unique, only one record can be returned. |
|
|
|
The query is performed by using db.QuerySingle (not db.Query, as you used for the movie listing), |
|
and the code puts the result into the row variable. The name row is arbitrary; you can name the |
|
variables anything you like.The variables initialized at the top are then filled with the movie details |
|
so that these values can be displayed in the text boxes. |
|
|
|
Testing the Edit Page (So Far) |
|
|
|
If you'd like to test your page, run the Movies page now and click an Edit link next to any movie. |
|
You'll see the EditMovie page with the details filled in for the movie you selected: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
90 |
|
|
|
|
|
Notice that the URL of the page includes something like ?id=10 (or some other number). So far |
|
you've tested that Edit links in the Movie page work, that your page is reading the ID from the |
|
query string, and that the database query to get a single movie record is working. |
|
|
|
You can change the movie information, but nothing happens when you click Submit Changes. |
|
|
|
Adding Code to Update the Movie with the User's Changes |
|
|
|
In the EditMovie.cshtml file, to implement the second function (saving changes), add the following |
|
code just inside the closing bracket of the @ block. (If you're sure exactly where to put the code, |
|
you can look at the complete page listing for the Edit Movie page that appears at the end of this |
|
tutorial.) |
|
|
|
if(IsPost){ |
|
Validation.RequireField("title", "You must enter a title"); |
|
Validation.RequireField("genre", "Genre is required"); |
|
Validation.RequireField("year", "You haven't entered a year"); |
|
Validation.RequireField("movieid", "No movie ID was submitted!"); |
|
|
|
title = Request.Form["title"]; |
|
genre = Request.Form["genre"]; |
|
year = Request.Form["year"]; |
|
movieId = Request.Form["movieId"]; |
|
|
|
if(Validation.IsValid()){ |
|
var db = Database.Open("WebPagesMovies"); |
|
var updateCommand = "UPDATE Movies " + |
|
"SET Title=@0, Genre=@1, Year=@2 WHERE Id=@3"; |
|
db.Execute(updateCommand, title, genre, year, movieId); |
|
Response.Redirect("~/Movies"); |
|
} |
|
} |
|
|
|
Again, this markup and code is similar to the code in AddMovie. The code is in an if(IsPost) |
|
block, because this code runs only when the user clicks the Submit Changes button — that is, |
|
when (and only when) the form has been posted. In this case, you're not using a test like |
|
if(IsPost && Validation.IsValid()) — that is,you're not combining both tests by using AND. In |
|
this page, you first determine whether there's a form submission (if(IsPost)), and only then |
|
register the fields for validation. Then you can test the validation results |
|
(if(Validation.IsValid()). The flow is slightly different than in the AddMovie.cshtml page, but |
|
the effect is the same. |
|
|
|
You get the values of the text boxes by using Request.Form["title"] and similar code for the |
|
other <input> elements. Notice that this time, the code gets the movie ID out of the hidden field |
|
(<input type="hidden">). When the page ran the first time, the code got the ID out of the query |
|
string. You get the value from the hidden field to make sure that you're getting the ID of the |
|
movie that was originally displayed, in case the query string was somehow altered since then. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
91 |
|
|
|
|
|
|
|
The really important difference between the AddMovie code and this code is that in this code you |
|
use the SQL Update statement instead of the Insert Into statement. The following example |
|
shows the syntax of the SQL Update statement: |
|
|
|
UPDATE table SET col1="value", col2="value", col3="value" ... WHERE ID = value |
|
|
|
You can specify any columns in any order, and you don't necessarily have to update every column |
|
during an Update operation. (You cannot update the ID itself, because that would in effect save |
|
the record as a new record, and that's not allowed for an Update operation.) |
|
|
|
Important The Where clause with the ID is very important, because that's how the |
|
database knows which database record you want to update. If you left off the Where |
|
clause, the database would update every record in the database. In most cases, that would |
|
be a disaster. |
|
|
|
In the code, the values to update are passed to the SQL statement by using placeholders. To |
|
repeat what we've said before: for security reasons, only use placeholders to pass values to a SQL |
|
statement. |
|
|
|
After the code uses db.Execute to run the Update statement,it redirects back to the listing page, |
|
where you can see the changes. |
|
|
|
Different SQL Statements, Different Methods |
|
|
|
You might have noticed that you use slightly different methods to run different SQL statements. |
|
To run a Select query that potentially returns multiple records, you use the Query method. To run |
|
a Select query that you know will return only one database item, you use the QuerySingle |
|
method. To run commands that make changes but that don't return database items, you use the |
|
Execute method. |
|
|
|
You have to have different methods because each of them returns different results, as you saw |
|
already in the difference between Query and QuerySingle. (The Execute method actually returns a |
|
value also — namely, the number of database rows that were affected by the command — but |
|
you've been ignoring that so far.) |
|
|
|
Of course, the Query method might return only one database row. However, ASP.NET always |
|
treats the results of the Query method as a collection. Even if the method returns just one row, |
|
you have to extract that single row from the collection. Therefore, in situations where you know |
|
you'll get back only one row, it's a bit more convenient to use QuerySingle. |
|
|
|
There are a few other methods that perform specific types of database operations. You can find a |
|
listing of database methods in the ASP.NET Web Pages API Quick Reference. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
92 |
|
|
|
Making Validation for the ID More Robust |
|
|
|
The first time that the page runs, you get the movie ID from the query string so that you can go |
|
get that movie from the database. You made sure that there actually was a value to go look for, |
|
which you did by using this code: |
|
|
|
if(!IsPost){ |
|
if(!Request.QueryString["ID"].IsEmpty()){ |
|
// Etc. |
|
} |
|
} |
|
|
|
You used this code to make sure that if a user gets to the EditMovies page without first selecting a |
|
movie in the Movies page, the page would display a user-friendly error message. (Otherwise, |
|
users would see an error that would probably just confuse them.) |
|
|
|
However, this validation isn't very robust. The page might also be invoked with these errors: |
|
|
|
• The ID isn't a number. For example, the page could be invoked with a URL like |
|
|
|
http://localhost:nnnnn/EditMovie?id=abc. |
|
|
|
• The ID is a number, but it references a movie that doesn't exist (for example, |
|
|
|
http://localhost:nnnnn/EditMovie?id=100934). |
|
|
|
If you're curious to see the errors that result from these URLs, run the Movies page. Select a |
|
movie to edit, and then change the URL of the EditMovie page to a URL that contains an |
|
alphabetic ID or the ID of a non-existent movie. |
|
|
|
So what should you do? The first fix is to make sure that not only is an ID passed to the page, but |
|
that the ID is an integer. Change the code for the !IsPost test to look like this example: |
|
|
|
if(!IsPost){ |
|
if(!Request.QueryString["ID"].IsEmpty() && Request.QueryString["ID"].IsInt()) |
|
{ |
|
// Etc. |
|
|
|
You've added a second condition to the IsEmpty test, linked with && (logical AND): |
|
|
|
Request.QueryString["ID"].IsInt() |
|
|
|
You might remember from the Programming Basics tutorial that methods like AsBool an AsInt |
|
convert a character string to some other data type. The IsInt method (and others, like IsBool and |
|
IsDateTime) are similar. However, they test only whether you can convert the string, without |
|
actually performing the conversion. So here you're essentially saying If the query string value can |
|
be converted to an integer ... . |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
93 |
|
|
|
The other potential problem is looking for a movie that doesn't exist. The code to get a movie |
|
looks like this code: |
|
|
|
var row = db.QuerySingle(dbCommand, movieId); |
|
|
|
If you pass a movieId value to the QuerySingle method that doesn't correspond to an actual |
|
movie, nothing is returned and the statements that follow (for example, title=row.Title) result |
|
in errors. |
|
|
|
Again there's an easy fix. If the db.QuerySingle method returns no results, the row variable will be |
|
null. So you can check whether the row variable is null before you try to get values from it. The |
|
following code adds an if block around the statements that get the values out of the row object: |
|
|
|
if(row != null) { |
|
title = row.Title; |
|
genre = row.Genre; |
|
year = row.Year; |
|
} |
|
else{ |
|
Validation.AddFormError("No movie was found for that ID."); |
|
// Use the following line instead for versions of ASP.NET Web Pages 2 earlier |
|
// than the RC release. |
|
//ModelState.AddFormError("No movie was found for that ID."); |
|
} |
|
|
|
With these two additional validation tests, the page becomes more bullet-proof. The complete |
|
code for the !IsPost branch now looks like this example: |
|
|
|
if(!IsPost){ |
|
if(!Request.QueryString["ID"].IsEmpty() && Request.QueryString["ID"].IsInt()) |
|
{ |
|
movieId = Request.QueryString["ID"]; |
|
var db = Database.Open("WebPagesMovies"); |
|
var dbCommand = "SELECT * FROM Movies WHERE ID = @0"; |
|
var row = db.QuerySingle(dbCommand, movieId); |
|
|
|
if(row != null) { |
|
title = row.Title; |
|
genre = row.Genre; |
|
year = row.Year; |
|
} |
|
else{ |
|
Validation.AddFormError("No movie was found for that ID."); |
|
// Use the following line instead for versions of ASP.NET |
|
// Web Pages 2 earlierthan the RC release. |
|
//ModelState.AddFormError("No movie was found for that ID."); |
|
} |
|
} |
|
else{ |
|
Validation.AddFormError("No movie was selected.") |
|
// Use the following line instead for versions of ASP.NET |
|
// Web Pages 2 earlierthan the RC release. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
94 |
|
|
|
|
|
//ModelState.AddFormError("No movie was selected."); |
|
} |
|
} |
|
|
|
We'll note once more that this task is a good use for an else block. If the tests don't pass, the else |
|
blocks set error messages. |
|
|
|
Adding a Link to Return to the Movies Page |
|
|
|
A final and helpful detail is to add a link back to the Movies page. In the ordinary flow of events, |
|
users will start at the Movies page and click an Edit link. That brings them to the EditMovie page, |
|
where they can edit the movie and click the button. After the code processes the change, it |
|
redirects back to the Movies page. |
|
|
|
However: |
|
|
|
• The user might decide not to change anything. |
|
• The user might have gotten to this page without first clicking an Edit link in the Movies |
|
|
|
page. |
|
|
|
Either way, you want to make it easy for them to return to the main listing. It's an easy fix — add |
|
the following markup just after the closing </form> tag in the markup: |
|
|
|
<p><a href="~/Movies">Return to movie listing</a></p> |
|
|
|
This markup uses the same syntax for an <a> element that you've seen elsewhere. The URL |
|
includes ~ to mean "root of the website." |
|
|
|
Testing the Movie Update Process |
|
|
|
Now you can test. Run the Movies page,and click Edit next to a movie. When the EditMovie page |
|
appears, make changes to the movie and clickSubmit Changes. When the movie listing appears, |
|
make sure that your changes are shown. |
|
|
|
To make sure that validation is working, click Edit for another movie. When you get to the |
|
EditMovie page, clear the Genre field (or Year field, or both) and try to submit your changes. |
|
You'll see an error, as you'd expect: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
95 |
|
|
|
Click the Return to movie listing link to abandon your changes and return to the Movies page. |
|
|
|
Coming Up Next |
|
|
|
In the next tutorial,you'll see how to delete a movie record. |
|
|
|
Additional Resources |
|
|
|
• Complete Listing for Movie Page (Updated with Edit Links) |
|
• Complete Page Listing for Edit Movie Page |
|
• |
|
|
|
SQL UPDATE Statement on the W3Schools site |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 6: Updating Database Data |
|
|
|
96 |
|
|
|
|
|
|
|
|
|
Tutorial 7: Deleting Database Data |
|
|
|
This tutorial shows you how to delete an individual database entry. |
|
|
|
What you'll learn: |
|
|
|
• How to select an individual record from a listing of records. |
|
• How to delete a single record from a database. |
|
• How to check that a specific button was clicked in a form. |
|
|
|
Features/technologies discussed: |
|
|
|
• The WebGrid helper. |
|
• The SQL Delete command. |
|
• The Database.Execute method to run a SQL Delete command. |
|
|
|
What You'll Build |
|
|
|
In the previous tutorial, you learned how to update an existing database record.This tutorial is |
|
similar, except that instead of updating the record,you'll delete it. The processes are much the |
|
same, except that deleting issimpler, so this tutorial will be short. |
|
|
|
In the Movies page,you'll update the WebGrid helper so that it displays a Delete link next to each |
|
movie to accompany the Editlink you added earlier. |
|
|
|
As with editing, when you click the Delete link, it takes you to a differentpage, where the movie |
|
information is already in a form: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 7: Deleting Database Data |
|
|
|
97 |
|
|
|
|
|
You can then click the button to delete the record permanently. |
|
|
|
Adding a Delete Link to the Movie Listing |
|
|
|
You'll start by adding a Delete link to the WebGrid helper. This link is similar to the Edit link you |
|
added in aprevious tutorial. |
|
|
|
Open the Movies.cshtml file. |
|
|
|
Change the WebGrid markup in the body of the page by adding acolumn. Here's the modified |
|
markup: |
|
|
|
@grid.GetHtml( |
|
tableStyle: "grid", |
|
headerStyle: "head", |
|
alternatingRowStyle: "alt", |
|
columns: grid.Columns( |
|
|
|
grid.Column(format: @<a href="~/[email protected]">Edit</a>), |
|
grid.Column("Title"), |
|
grid.Column("Genre"), |
|
grid.Column("Year"), |
|
grid.Column(format: @<a href="~/[email protected]">Delete</a>) |
|
|
|
) |
|
) |
|
|
|
The new column is this one: |
|
|
|
grid.Column(format: @<a href="~/[email protected]">Delete</a>) |
|
|
|
The way the grid is configured, the Edit column is leftmostin the grid and the Delete column is |
|
rightmost. (There's acomma after the Year column now, in case you didn't notice that.)There's |
|
nothing special about where these link columns go, and you could aseasily put them next to each |
|
other. In this case, they're separate to make them harder to get mixed up. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 7: Deleting Database Data |
|
|
|
98 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The new column shows a link (<a> element)whose text says "Delete". The target of the link (its |
|
href attribute)is code that ultimately resolves to something like this URL, with the idvalue |
|
different for each movie: |
|
|
|
http://localhost:43097/DeleteMovie?id=7 |
|
|
|
This link will invoke a page named DeleteMovie and pass it the ID of themovie you've selected. |
|
|
|
This tutorial won't go into detail about how this link is constructed,because it's almost identical to |
|
the Edit link from theprevious tutorial (Updating Database Data). |
|
|
|
Creating the Delete Page |
|
|
|
Now you can create the page that will be the target for the Deletelink in the grid. |
|
|
|
Important The technique of firstselecting a record to delete and then using a separate |
|
page and button to confirm the process is extremely important for security. As you've read |
|
in previous tutorials, making any sort of change toyour website should alwaysbe done |
|
using a form — that is, using an HTTP POST operation. If you made itpossible to change the |
|
site just by clicking a link (that is, using a GEToperation), people could make simple |
|
requests to your site and delete your data. Even a search-engine crawler that's indexing |
|
your site could inadvertently delete data just by following links. |
|
|
|
When your app lets people change a record, you have to present the record to the user for editing |
|
anyway. Butyou might be tempted to skip this step for deleting a record. Don't skip that step, |
|
though. (It's also helpful for users to see the record and confirm that they're deleting the record |
|
that they intended.) |
|
|
|
In a subsequent tutorial set, you'll see how to add loginfunctionality so a user would have to log in |
|
before deleting a record. |
|
|
|
Create a page named DeleteMovie.cshtml and replace what's in the file with the following |
|
markup: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 7: Deleting Database Data |
|
|
|
99 |
|
|
|
|
|
|
|
<html> |
|
<head> |
|
<title>Delete a Movie</title> |
|
</head> |
|
<body> |
|
<h1>Delete a Movie</h1> |
|
@Html.ValidationSummary() |
|
<p><a href="~/Movies">Return to movie listing</a></p> |
|
|
|
<form method="post"> |
|
<fieldset> |
|
<legend>Movie Information</legend> |
|
|
|
<p><span>Title:</span> |
|
<span>@title</span></p> |
|
|
|
<p><span>Genre:</span> |
|
<span>@genre</span></p> |
|
|
|
<p><span>Year:</span> |
|
<span>@year</span></p> |
|
|
|
<input type="hidden" name="movieid" value="@movieId" /> |
|
<p><input type="submit" name="buttonDelete" value="Delete Movie" /></p> |
|
</fieldset> |
|
</form> |
|
</body> |
|
</html> |
|
|
|
This markup is like the EditMovie pages, except that instead of using textboxes |
|
(<input type="text">), the markup includes <span>elements. There's nothing here to edit. All you |
|
have to do is display the moviedetails so that users can make sure that they're deleting the right |
|
movie. |
|
|
|
The markup already contains a link that lets the user return to the movielisting page. |
|
|
|
As in the EditMovie page, the ID of the selected movie is stored ina hidden field. (It's passed into |
|
the page in the first place as a query stringvalue.)There's an Html.ValidationSummary call thatwill |
|
display validation errors. In this case, the errormight be that no movie ID was passed to the page |
|
or that the movie ID is invalid. This situation could occur if someoneran this page without first |
|
selecting a movie in the Movies page. |
|
|
|
The button caption is Delete Movie, and its name attributeis set to buttonDelete. The name |
|
attribute will be usedin the code to identify the button that submitted the form. |
|
|
|
You'll have to write code to 1) read the movie details when the page is firstdisplayed and 2) |
|
actually delete the movie when the user clicks the button. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 7: Deleting Database Data |
|
|
|
100 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Adding Code to Read a Single Movie |
|
|
|
At the top of the DeleteMovie.cshtml page, add the following codeblock: |
|
|
|
@{ |
|
var title = ""; |
|
var genre = ""; |
|
var year = ""; |
|
var movieId = ""; |
|
|
|
if(!IsPost){ |
|
if(!Request.QueryString["ID"].IsEmpty() && |
|
Request.QueryString["ID"].IsInt()){ |
|
movieId = Request.QueryString["ID"]; |
|
var db = Database.Open("WebPagesMovies"); |
|
var dbCommand = "SELECT * FROM Movies WHERE ID = @0"; |
|
var row = db.QuerySingle(dbCommand, movieId); |
|
if(row != null) { |
|
title = row.Title; |
|
genre = row.Genre; |
|
year = row.Year; |
|
} |
|
else{ |
|
Validation.AddFormError("No movie was found for that ID."); |
|
// If you are using a version of ASP.NET Web Pages 2 that's |
|
// earlier than the RC release, comment out the preceding |
|
// statement and uncomment the following one. |
|
//ModelState.AddFormError("No movie was found for that ID."); |
|
} |
|
} |
|
else{ |
|
Validation.AddFormError("No movie was found for that ID."); |
|
// If you are using a version of ASP.NET Web Pages 2 that's |
|
// earlier than the RC release, comment out the preceding |
|
// statement and uncomment the following one. |
|
//ModelState.AddFormError("No movie was found for that ID."); |
|
} |
|
} |
|
} |
|
|
|
This markup is the same as the corresponding code in the EditMovie page. It gets the movie ID out |
|
of the query string and uses the ID to read a recordfrom the database. The code includes the |
|
validation test (IsInt()and row != null) to make sure that the movie ID being passed to thepage |
|
is valid. |
|
|
|
Remember that this code should only run the first time the page runs. You don't want to re-read |
|
the movie record from the database when the user clicksthe Delete Movie button.Therefore, |
|
code to read the movie is inside a test that says if(!IsPost) — that is, if the request is not a post |
|
operation (form submission). |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 7: Deleting Database Data |
|
|
|
101 |
|
|
|
|
|
Adding Code to Delete the Selected Movie |
|
|
|
To delete the movie when the user clicks the button, add the following codejust inside the closing |
|
bracket of the @ block: |
|
|
|
if(IsPost && !Request["buttonDelete"].IsEmpty()){ |
|
movieId = Request.Form["movieId"]; |
|
var db = Database.Open("WebPagesMovies"); |
|
var deleteCommand = "DELETE FROM Movies WHERE ID = @0"; |
|
db.Execute(deleteCommand, movieId); |
|
Response.Redirect("~/Movies"); |
|
} |
|
|
|
This code is similar to the code for updating an existing record, but simpler. The code basically |
|
runs a SQL Delete statement. |
|
|
|
As in the EditMovie page, the code is inan if(IsPost) block. This time, the if() condition isa little |
|
more complicated: |
|
|
|
if(IsPost && !Request["buttonDelete"].IsEmpty()) |
|
|
|
There are two conditions here. The first is that the page is being submitted,as you've seen before |
|
— if(IsPost). |
|
|
|
The second condition is !Request["buttonDelete"].IsEmpty(),meaning that the request has an |
|
object named buttonDelete.Admittedly, it's an indirect way of testing which buttonsubmitted the |
|
form. If a form contains multiple submit buttons, only the name ofthe button that was clicked |
|
appears in the request. Therefore, logically, ifthe name of a particular button appears in the |
|
request — or as stated in thecode, if that button isn't empty — that's the button that submitted |
|
the form. |
|
|
|
The && operator means "and" (logical AND). Therefore the entire if condition is ... |
|
|
|
This request is a post (not a first-time request) |
|
|
|
AND |
|
|
|
The buttonDelete button was the button that submitted the form. |
|
|
|
This form (in fact, this page) contains only one button, so the additional testfor buttonDelete is |
|
technically not required. Still, you're about to perform an operation that will permanently remove |
|
data. So you want to be as sure as possible that you're performing the operation only when the |
|
user hasexplicitly requested it. For example, suppose that you expanded this page later and |
|
addedother buttons to it. Even then, the code that deletes the moviewill run only if the |
|
buttonDelete button was clicked. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 7: Deleting Database Data |
|
|
|
102 |
|
|
|
|
|
|
|
As in the EditMovie page, you get the ID from the hidden field andthen run the SQL command. |
|
The syntax for the Delete statement is: |
|
|
|
DELETE FROM table WHERE ID = value |
|
|
|
It's vital to include the WHERE clause and the ID. If you leaveout the WHERE clause, all the records |
|
in the table will be deleted. As youhave seen, you pass the ID value to the SQL command by using |
|
a placeholder. |
|
|
|
Testing the Movie Delete Process |
|
|
|
Now you can test. Run the Movies page, and click Deletenext to a movie. When the DeleteMovie |
|
page appears, click Delete Movie. |
|
|
|
When you click the button, the code deletes the movies and returns to themovie listing. There |
|
you can search for the deleted movie and confirm that it's been deleted. |
|
|
|
Coming Up Next |
|
|
|
The next tutorial shows you how to give all the pages on your site a commonlook and layout. |
|
|
|
Additional Resources |
|
|
|
• Complete Listing for Movie Page (Updated with Delete Links) |
|
• Complete Listing for DeleteMovie Page |
|
• |
|
• SQL DELETE Statement on the W3Schools site |
|
|
|
Introduction to ASP.NET Web Programming by Using the Razor Syntax |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 7: Deleting Database Data |
|
|
|
103 |
|
|
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
This tutorial shows you how to use layouts to create a consistent look for the pages on a site that |
|
uses ASP.NET Web Pages. |
|
|
|
What you'll learn: |
|
|
|
• What a layout page is. |
|
• How to combine layout pages with dynamic content. |
|
• How to pass values to a layout page. |
|
|
|
About Layouts |
|
|
|
The pages you've created so far have all been complete, standalone pages. They all belong to the |
|
same site, but they don't have any common elements or a standard look. |
|
|
|
Most sites do have a consistent look and layout. For example, if you go to the Microsoft.com/web |
|
site and look around, you see that the pages all adhere to an overall layout and to a visual theme: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
104 |
|
|
|
An inefficient way to create this layout would be to define a header, navigation bar, and footer |
|
separately on each of your pages. You'd be duplicating the same markup each time. If you wanted |
|
to change something (for example, update the footer), you'd have to change each page |
|
separately. |
|
|
|
That's where layout pages come in. In ASP.NET Web Pages, you can define a layout page that |
|
provides an overall container for pages on your site. For example, the layout page can contain the |
|
header, navigation area, and footer. The layout page includes a placeholder where the main |
|
content goes. |
|
|
|
You can then define individual content pages that contain the markup and the code for only that |
|
page. Content pages don't have to be complete HTML pages; they don't even have to have a |
|
<body> element. They also have a line of code that tells ASP.NET what layout page you want to |
|
display the content in. Here's a picture that shows roughly how this relationship works: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
105 |
|
|
|
|
|
This interaction is easy to understand when you see it in action. In this tutorial, you'll change your |
|
movies pages to use a layout. |
|
|
|
Adding a Layout Page |
|
|
|
You'll start by creating a layout page that defines a typical page layout with a header, footer, and |
|
an area for the main content. In the WebPagesMovies site, add a CSHTML page named |
|
_Layout.cshtml. |
|
|
|
The leading underscore ( _ ) character is significant. If a page's name starts with an underscore, |
|
ASP.NET won't directly send that page to the browser. This convention lets you define pages that |
|
are required for your site but that users shouldn't be able to request directly. |
|
|
|
Replace the content in the page with the following: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
106 |
|
|
|
|
|
|
|
<!DOCTYPE html> |
|
<html> |
|
<head> |
|
<title>@Page.Title</title> |
|
<link href="~/Styles/Movies.css" rel="stylesheet" type="text/css" /> |
|
</head> |
|
<body> |
|
<div id="container"> |
|
<div id="header"> |
|
<h1>My Movie Site</h1> |
|
</div> |
|
<div id="main"> |
|
@RenderBody() |
|
</div> |
|
<div id="footer"> |
|
© @DateTime.Now.Year My Movie Site |
|
</div> |
|
</div> |
|
</body> |
|
</html> |
|
|
|
As you can see, this markup is just HTML that uses <div> elements to define three sections in the |
|
page plus one more <div> element to hold the three sections. The footer contains a bit of Razor |
|
code: @DateTime.Now.Year, which will render the current year at that location in the page. |
|
|
|
Notice that there's a link to a style sheet named Movies.css. The style sheet is where the details of |
|
the physical layout of the elements will be defined. You'll create that in a moment. |
|
|
|
The only unusual feature in this _Layout.cshtml page is the @Render.Body() line. That's the |
|
placeholder where the content will go when this layout is merged with another page. |
|
|
|
Adding a .css File |
|
|
|
The preferred way to define the actual arrangement (that is, appearance) of elements on the |
|
page is to use cascading style sheet (CSS) rules. So you'll create a .css file that has the rules for |
|
your new layout. |
|
|
|
In WebMatrix, select the root of your site. Then in the Files tab of the ribbon, click the arrow |
|
under the New button and then click New Folder. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
107 |
|
|
|
|
|
Name the new folder Styles. |
|
|
|
Inside the new Styles folder, create a file named Movies.css. |
|
|
|
Replace the contents of the new .css file with the following: |
|
|
|
html{ height:100%; margin:0; padding:0; } |
|
|
|
body { |
|
height:60%; |
|
font-family:'Trebuchet MS', 'Arial', 'Helvetica', 'sans-serif'; |
|
font-size:10pt; |
|
background-color: LightGray; |
|
line-height:1.6em; |
|
} |
|
|
|
h1{ font-size:1.6em; } |
|
h2{ font-size:1.4em; } |
|
|
|
#container{ |
|
min-height:100%; |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
108 |
|
|
|
|
|
|
|
|
|
|
|
|
|
position:relative; |
|
left:10%; |
|
} |
|
|
|
#header{ |
|
padding:8px; |
|
width:80%; |
|
background-color:#4b6c9e; |
|
color:White; |
|
} |
|
|
|
#main{ |
|
width:80%; |
|
padding: 8px; |
|
padding-bottom:4em; |
|
background-color:White; |
|
} |
|
|
|
#footer{ |
|
position:absolute; |
|
bottom:0; |
|
width:80%; |
|
height:2em; |
|
padding:8px; |
|
margin-top:-2em; |
|
background-color:LightGray; |
|
} |
|
|
|
.head { background-color: #E8E8E8; font-weight: bold; color: #FFF; } |
|
.grid th, .grid td { border: 1px solid #C0C0C0; padding: 5px; } |
|
.alt { background-color: #E8E8E8; color: #000; } |
|
.selected {background-color:Yellow;} |
|
span.caption {width:100px;} |
|
span.dataDisplay {font-weight:bold;} |
|
|
|
We won't say much about these CSS rules, except to note two things. One is that in addition to |
|
setting fonts and sizes, the rules use absolute positioning to establish the location of the header, |
|
footer, and main content area. If you're new to positioning in CSS, you can read the CSS |
|
Positioning tutorial at the W3Schools site. |
|
|
|
The other thing to note is that at the bottom, we've copied the style rules that were originally |
|
defined individually in the Movies.cshtml file. These rules were used in the Displaying Data |
|
tutorial to make the WebGrid helper render markup that added stripes to the table. (If you're going |
|
to use a .css file for style definitions, you might as well put the style rules for the whole site in it.) |
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|
|
Updating the Movies File to Use the Layout |
|
|
|
Now you can update the existing files in your site to use the new layout. Open the Movies.cshtml |
|
file. At the top, as the first line of code, add the following: |
|
|
|
Layout = "~/_Layout.cshtml"; |
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|
Introducing ASP.NET Web Pages 2 |
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|
Tutorial 8: Creating a Consistent Layout |
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|
109 |
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|
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|
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|
|
The page now starts out this way: |
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|
|
@{ |
|
Layout = "~/_Layout.cshtml"; |
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|
|
var db = Database.Open("WebPagesMovies") ; |
|
var selectCommand = "SELECT * FROM Movies"; |
|
var searchTerm = ""; |
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|
|
// Etc. |
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|
|
This one line of code tells ASP.NET that when the Movies page runs, it should be merged with the |
|
_Layout.cshtml file. |
|
|
|
Since the Movies.cshtml file now uses a layout page, you can remove the markup from the |
|
Movies.cshtml page that's taken care of by the _Layout.cshtml file. Take out the <!DOCTYPE>, |
|
<html>,and <body> opening and closing tags. Take out the entire <head> element and its contents, |
|
which includes the style rules for the grid, since you've now got those rules in a .css file.While |
|
you're at it, change the existing <h1> element to an <h2> element; you have an <h1> element in the |
|
layout page already. Change the <h2> text to "List Movies". |
|
|
|
Normally you wouldn't have to make these sorts of changes in a content page. When you start |
|
your site out with a layout page, you create content pages without all these elementsto begin |
|
with. In this case, though, you're converting a standalone page to one that uses a layout, so |
|
there's a bit of cleanup. |
|
|
|
When you're finished, the Movies.cshtml page will look like the following: |
|
|
|
@{ |
|
Layout = "~/_Layout.cshtml"; |
|
|
|
var db = Database.Open("WebPagesMovies") ; |
|
var selectCommand = "SELECT * FROM Movies"; |
|
var searchTerm = ""; |
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
searchTerm = Request.QueryString["searchGenre"]; |
|
} |
|
|
|
if(!Request.QueryString["searchTitle"].IsEmpty() ) { |
|
selectCommand = "SELECT * FROM Movies WHERE Title LIKE @0"; |
|
searchTerm = "%" + Request.QueryString["searchTitle"] + "%"; |
|
} |
|
|
|
var selectedData = db.Query(selectCommand, searchTerm); |
|
var grid = new WebGrid(source: selectedData, defaultSort: "Genre", |
|
rowsPerPage:3); |
|
} |
|
<h2>List Movies</h2> |
|
<form method="get"> |
|
<div> |
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|
Introducing ASP.NET Web Pages 2 |
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|
Tutorial 8: Creating a Consistent Layout |
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|
110 |
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|
<label for="searchGenre">Genre to look for:</label> |
|
<input type="text" name="searchGenre" |
|
value="@Request.QueryString["searchGenre"]" /> |
|
<input type="Submit" value="Search Genre" /><br/> |
|
(Leave blank to list all movies.)<br/> |
|
</div> |
|
<div> |
|
<label for="SearchTitle">Movie title contains the following:</label> |
|
<input type="text" name="searchTitle" |
|
value="@Request.QueryString["searchTitle"]" /> |
|
<input type="Submit" value="Search Title" /><br/> |
|
</div> |
|
</form> |
|
<div> |
|
@grid.GetHtml( |
|
tableStyle: "grid", |
|
headerStyle: "head", |
|
alternatingRowStyle: "alt", |
|
columns: grid.Columns( |
|
grid.Column(format: @<a href="~/[email protected]">Edit</a>), |
|
grid.Column("Title"), |
|
grid.Column("Genre"), |
|
grid.Column("Year"), |
|
grid.Column(format: @<a href="~/[email protected]">Delete</a>) |
|
) |
|
) |
|
</div> |
|
<p><a href="~/AddMovie">Add a movie</a></p> |
|
|
|
Testing the Layout |
|
|
|
Now you can see what the layout looks like. In WebMatrix, right-click the Movies.cshtml page and |
|
select Launch in browser. When the browser displays the page, it looks like this page: |
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|
Introducing ASP.NET Web Pages 2 |
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|
Tutorial 8: Creating a Consistent Layout |
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|
111 |
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|
|
ASP.NET has merged the content of the Movies.cshtml page into the _Layout.cshtml page right |
|
where the RenderBody method is. And of course the _Layout.cshtml page references a .css file that |
|
defines the look of the page. |
|
|
|
Updating the AddMovie Page to Use the Layout |
|
|
|
The real benefit of layouts is that you can use them for all the pages in your site. Open the |
|
AddMovie.cshtml page. |
|
|
|
You might remember that the AddMovie.cshtml page originally had some CSS rules in it to define |
|
the look of validation error messages. Since you have a .css file for your site now, you can move |
|
those rules to the .css file. Remove them from the AddMovie.cshtml file and add them to the |
|
bottom of the Movies.css file. You are moving the following rules: |
|
|
|
.field-validation-error { |
|
font-weight:bold; |
|
color:red; |
|
background-color:yellow; |
|
} |
|
.validation-summary-errors{ |
|
border:2px dashed red; |
|
color:red; |
|
background-color:yellow; |
|
font-weight:bold; |
|
margin:12px; |
|
} |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
112 |
|
|
|
|
|
Now make the same sorts of changes in AddMovie.cshtml that you did for Movies.cshtml — add |
|
Layout="~/_Layout.cshtml; and remove the HTML markup that's now extraneous. Change the |
|
<h1> element to <h2>. When you're done, the page will look like this example: |
|
|
|
@{ |
|
Layout = "~/_Layout.cshtml"; |
|
Validation.RequireField("title", "You must enter a title"); |
|
Validation.RequireField("genre", "Genre is required"); |
|
Validation.RequireField("year", "You haven't entered a year"); |
|
|
|
var title = ""; |
|
var genre = ""; |
|
var year = ""; |
|
|
|
if(IsPost){ |
|
if(Validation.IsValid()){ |
|
title = Request.Form["title"]; |
|
genre = Request.Form["genre"]; |
|
year = Request.Form["year"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
var insertCommand = |
|
"INSERT INTO Movies (Title, Genre, Year) Values(@0, @1, @2)"; |
|
db.Execute(insertCommand, title, genre, year); |
|
Response.Redirect("~/Movies"); |
|
} |
|
} |
|
} |
|
<h2>Add a Movie</h2> |
|
@Html.ValidationSummary() |
|
<form method="post"> |
|
<fieldset> |
|
<legend>Movie Information</legend> |
|
<p><label for="title">Title:</label> |
|
<input type="text" name="title" value="@Request.Form["title"]" /> |
|
@Html.ValidationMessage("title") |
|
</p> |
|
|
|
<p><label for="genre">Genre:</label> |
|
<input type="text" name="genre" value="@Request.Form["genre"]" /> |
|
@Html.ValidationMessage("genre") |
|
</p> |
|
|
|
<p><label for="year">Year:</label> |
|
<input type="text" name="year" value="@Request.Form["year"]" /> |
|
@Html.ValidationMessage("year") |
|
</p> |
|
|
|
<p><input type="submit" name="buttonSubmit" value="Add Movie" /></p> |
|
</fieldset> |
|
</form> |
|
|
|
Run the page. Now it looks like this illustration: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
113 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
You want to make similar changes to the pages in the site — EditMovie.cshtmland |
|
DeleteMovie.cshtml. However, before you do, you can make another change to the layout that |
|
makes it a little more flexible. |
|
|
|
Passing Title Information to the Layout Page |
|
|
|
The _Layout.cshtml page that you created has a <title> element that's set to "My Movie Site". |
|
Most browsers display the content of this element as the text on a tab: |
|
|
|
This title information is generic. Suppose that you want the title text to be more specific to the |
|
current page. (The title text is also used by search engines to determine what your page is about.) |
|
You can pass information from a content page like Movies.cshtml or AddMovie.cshtml to the |
|
layout page, and then use that information to customize what the layout page renders. |
|
|
|
Open the Movies.cshtml page again. In the code at the top, add the following line: |
|
|
|
Page.Title = "List Movies"; |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
114 |
|
|
|
|
|
|
|
The Page object is available on all .cshtml pages and is for this purpose, namely to share |
|
information between a page and its layout. |
|
|
|
Open the _Layout.cshtml page. Change the <title> element so that it looks like this markup: |
|
|
|
<title>@Page.Title</title> |
|
|
|
This code renders whatever is in the Page.Title property right at that location in the page. |
|
|
|
Run the Movies.cshtml page. This time the browser tab shows what you passed as the value of |
|
Page.Title: |
|
|
|
If you want, view the page source in the browser. You can see that the <title> element is |
|
rendered as <title>List Movies</title>. |
|
|
|
The Page Object |
|
|
|
A useful feature of Page is that it's a dynamic object — the Title propertyis not a fixed or reserved |
|
name. You can use any name for a value of the Page object. For example, you could as easily have |
|
passed the title by using a property named Page.CurrentName or Page.MyPage. The only restriction |
|
is that the name has to follow the normal rules for what properties can be named. (For example, |
|
the name can't contain a space.) |
|
|
|
You can pass any number of values by using the Page object. If you wanted to pass movie |
|
information to the layout page, you could pass values by using something like Page.MovieTitle |
|
and Page.Genre and Page.MovieYear. (Or any other names that you invented to store the |
|
information.) The only requirement — which is probably obvious — is that you have to use the |
|
same names in the content page and the layout page. |
|
|
|
The information you pass by using the Page object isn't limited to just text to display on the layout |
|
page. You can pass a value to the layout page, and then code in the layout page can use the value |
|
to decide whether to display a section of the page, what .css file to use, and so on. The values you |
|
pass in the Page object are like any other values that you use in code. It's just that the values |
|
originate in the content page and are passed to the layout page. |
|
|
|
Open the AddMovie.cshtml page and add a line to the top of the code that provides a title for the |
|
AddMovie.cshtml page: |
|
|
|
Page.Title = "Add a Movie"; |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
115 |
|
|
|
|
|
Run the AddMovie.cshtml page. You see the new title there: |
|
|
|
Updating the Remaining Pages to Use the Layout |
|
|
|
Now you can finish the remaining pages in your site so that they use the new layout. Open |
|
EditMovie.cshtml and DeleteMovie.cshtml in turn and make the same changes in each. |
|
|
|
Add the line of code that links to the layout page: |
|
|
|
Layout = "~/_Layout.cshtml"; |
|
|
|
Add a line to set the title of the page: |
|
|
|
Page.Title = "Edit a Movie"; |
|
|
|
or: |
|
|
|
Page.Title = "Delete a Movie"; |
|
|
|
Remove all the extraneous HTML markup — basically, leave only the bits that are inside the |
|
<body> element (plus the code block at the top). |
|
|
|
Change the <h1> element to be an <h2> element. |
|
|
|
When you've made these changes, test each and make sure thatit's displaying properly and that |
|
the title is correct. |
|
|
|
Parting Thoughts About Layout Pages |
|
|
|
In this tutorial you created a _Layout.cshtml page and used the RenderBody method to merge |
|
content from another page. That's the basic pattern for using layouts in Web Pages. |
|
|
|
Layout pages have additional features that we didn't cover here. For example, you can nest layout |
|
pages — one layout page can in turn reference another. Nested layouts can be useful if you're |
|
working with subsections of a site that require different layouts. You can also use additional |
|
methods (for example, RenderSection) to set up named sections in the layout page. |
|
|
|
The combination of layout pages and .css files is powerful. As you'll see in the next tutorial series, |
|
in WebMatrix you can create a site based on a template, which gives you a site that has prebuilt |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
116 |
|
|
|
|
|
functionality in it. The templates make good use of layout pages and CSS to create sites that look |
|
great and that have features like menus. Here's a screenshot of the home page from a site based |
|
on a template, showing features that use layout pages and CSS: |
|
|
|
Coming Up Next |
|
|
|
In the next tutorial, you'll learn how to publish your site to the Internet so everyone can see it. |
|
|
|
Additional Resources |
|
|
|
• Complete Listing for Movie Page (Updated to Use a Layout Page) |
|
• Complete Page Listing for Add Movie Page (Updated for Layout) |
|
• Complete Page Listing for Delete Movie Page (Updated for Layout) |
|
• Complete Page Listing for Edit Movie Page (Updated for Layout) |
|
• Creating a Consistent Look — An article that provides some more detail on working with |
|
|
|
layouts. It also describes how to pass a value to a layout page that shows or hides some of |
|
the content. |
|
|
|
• Nested Layout Pages with Razor — Mike Brind blogs an example of how to nest layout |
|
|
|
pages. (Includes a download of the pages.) |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 8: Creating a Consistent Layout |
|
|
|
117 |
|
|
|
|
|
|
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
What you'll learn: |
|
|
|
• How to publish your site to the Internet. |
|
• What's coming up in the next tutorial set. |
|
|
|
Publishing Your Site |
|
|
|
Up to now, you've done all your work on a local computer, including testing your pages. To run |
|
your .cshtml pages, you've used the web server that's built into WebMatrix, namely IIS Express. |
|
But of course no one can see the site you've created except you. To let others work with your site, |
|
you have to publish it to the Internet. |
|
|
|
Unless you have access to a public web server already, publishing means that you have to have an |
|
account with a hosting provider. A hosting provider is a company that owns publicly accessible |
|
web servers and that will rent you space for your site. Hosting plans run from a few dollars a |
|
month (or even free) for small sites to many hundreds of dollars a month for high-volume |
|
commercial websites. |
|
|
|
Note You might have access to a public web server via the internet service provider (ISP) |
|
that you use to get internet service at home. However, your hosting provider must support |
|
ASP.NET Web Pages. Many ISPs don't, but it's always worth checking. |
|
|
|
In this tutorial, we'll give you an overview of how to publish. It's not practical to provide exact |
|
details for everything, because the process differs a bit for every hosting provider. But you'll get a |
|
good idea of how the process works. |
|
|
|
Selecting a hosting provider |
|
|
|
The first step is to find a hosting provider. You can look for one by searching the web or right from |
|
within WebMatrix. |
|
|
|
In the WebMatrix ribbon, click the Publish button. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
118 |
|
|
|
|
|
The Publish Settings dialog box is displayed. |
|
|
|
Click the Find web hosting link. |
|
|
|
You go to a page on the Microsoft site that lists hosting providers that support ASP.NET. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
119 |
|
|
|
|
|
|
|
Obviously, it can be difficult to know now exactly what hosting features you might require over |
|
the long term. Here are a couple of things to consider: |
|
|
|
• |
|
|
|
For purposes of the WebPagesMovies site, you don't have to have a separate add-on for |
|
SQL Server, which often costs extra. In your site, you're using SQL Server Compact Edition, |
|
which is self-contained. However, you might need SQL Server access for some future |
|
website work you do. If you think you might, make sure that you can add SQL Server |
|
capability later. |
|
|
|
• Check whether the hosting provider supports the Web Deploy publishing protocol. You |
|
|
|
can publish by using FTP protocol, but it's more convenient to use Web Deploy. |
|
|
|
Some sites offer a free trial period. A free trial is a good way to try publishing and hosting while |
|
you're still experimenting with WebMatrix and ASP.NET Web Pages. |
|
|
|
Pick one that you like. For this tutorial, we selected DiscountASP.NET, because while we were |
|
creating the tutorial, that company had a promotion that let people host a site free for a few |
|
months. |
|
|
|
Note Our choice of a hosting provider for this tutorial shouldn't be interpreted as an |
|
endorsement of that company over any other. But we had to pick one for illustration, and |
|
DiscountASP.NET is one of the many companies that supports ASP.NET Web Pages and the |
|
Web Deploy protocol for publishing. |
|
|
|
Typically, after you've signed up with the hosting provider, the company sends you an email that |
|
contains a user name and password, the URL of the web server, and so on. If the hosting company |
|
supports Web Deploy protocol, they might send you a file that contains publish settings, or let you |
|
download one. A publish settings file simplifies the process for you. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
120 |
|
|
|
|
|
Publishing the site |
|
|
|
When you've signed up and are ready to publish, click the Publish button in the WebMatrix |
|
ribbon. The Publish Settings dialog box is displayed. |
|
|
|
If the hosting provider sent you a publish settings file, click the Import publish settings link and |
|
import the file. If you don't have a publish settings file, fill in the fields by using the values that the |
|
hosting company sent you in email. Here's what the Publish Settings dialog box might look like |
|
when you're done: |
|
|
|
Click Validate Connection. If everything is ok, the dialog box reports Connected successfully, |
|
which means it can communicate with the hosting provider's server. |
|
|
|
If there's a problem, WebMatrix does its best to tell you what the problem is: |
|
|
|
Click Save to save your settings. WebMatrix offers to perform a test to make sure that it can |
|
communicate correctly with the hosting site: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
121 |
|
|
|
|
|
|
|
|
|
Click Yes. WebMatrix uploads some sample files to the hosting provider. When the compatibility |
|
test is done, WebMatrix reports the results: |
|
|
|
If you're ready to go, go ahead and click Continue to start the publish process for real. WebMatrix |
|
figures out what files are in your site and are already on the host server (right now, none) and |
|
gives you a preview of the publish process: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
122 |
|
|
|
|
|
|
|
The list of files to publish includes the web pages that you've created like Movies.cshtml. The list |
|
also includes files for helpers that you've installed, the files to run SQL Server Compact Edition for |
|
your database, and so on. As a result, the initial publish process can be substantial. |
|
|
|
Click Continue. WebMatrix copies your files to the hosting provider's server. When it's done, the |
|
results are reported in the status bar: |
|
|
|
To see your live site, click the link in the status bar. Add Movies to the URL, and you'll see the |
|
Movies.cshtml file that you created: |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
123 |
|
|
|
|
|
|
|
|
|
Updating the live site: Republishing |
|
|
|
Once you've published your site, there are two copies of it — the version on your computer and |
|
the version on the hosting provider's server. You'll probably want to continue developing the site |
|
(if nothing else, as part of the next tutorial set).When you do, you have to republish your site in |
|
order to copy changes from your computer to the hosting provider's server. The publish process |
|
in WebMatrix can determine what files have changed on your site and publish just those files. |
|
|
|
To see how republishing works, open the Movies.cshtml site, make some small change, and then |
|
save the file. For example, change the title to Movies - Updated. |
|
|
|
Click the Publish button in the ribbon. WebMatrix determines what's changed and shows you a |
|
preview of the files it will publish. |
|
|
|
Important!By default, WebMatrix publishes your database (.sdf file) only the first time you |
|
publish the site. Once your site is published and people are interacting with the website, |
|
the database on the live site typically has the site's real data. You have to be very careful |
|
not to overwrite the live database with the .sdf file that's on your computer, which usually |
|
contains only test data. That's why you see the warning Publishing will overwrite any |
|
remote databases, and why the check box for WebPagesMovies.sdf is cleared by default. |
|
|
|
Click Continue. WebMatrix publishes the changed files and shows you a success message, like it |
|
did the first time you published. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
124 |
|
|
|
|
|
Goto the live site (you can click the link in the success message if it's still showing) and verify that |
|
your change has been published. |
|
|
|
Editing files remotely |
|
|
|
As an alternative to changing your site and then republishing, you can edit remote files directly in |
|
WebMatrix. In this scenario, you open a file that's on the hosting provider's server, and |
|
WebMatrix downloads a copy of it for you to edit. Every time you save the file, WebMatrix sends |
|
the changes to the hosting site. |
|
|
|
Remote editing is an easy way to make changes to your live site. However, the changes you make |
|
this way aren't synchronized with the files in your local site. To synchronize the local files with the |
|
remote site, you can download the remote files. This process works much like publishing, except |
|
in reverse. |
|
|
|
We won't describe more about the remote-editing and remote-download facilities of WebMatrix |
|
here. They're quite useful if multiple people have to work on the same site on different |
|
computers. For more information, see Publish and Edit a Remote Site with WebMatrix 2. |
|
|
|
Preview of the Next Tutorial Set |
|
|
|
In this tutorial you've created a site that's functional and that illustrates much of the functionality |
|
of ASP.NET Web Pages. But there's plenty more to learn. The next tutorial set continues with your |
|
Movies site and teaches you the following: |
|
|
|
• How to start a site from a template, which instantly gives you a professional layout plus |
|
|
|
built-in functionality for common tasks. |
|
|
|
• More about how to work with forms — radio buttons, checkboxes, drop-down lists, etc. |
|
• How to perform more sophisticated database searches. |
|
• How to add social media to your site — for example, adding a Facebook "Like" button. |
|
• How to begin adding client-side functionality to your site (by using jQuery), which gives |
|
|
|
the user a very responsive experience. |
|
|
|
• How to add images to the site, including images uploaded by users. |
|
• How to send email from your site. |
|
• How to add login security to your site, so that some functions (like deleting a movie) are |
|
|
|
available only to users who've been authorized. |
|
|
|
Additional Resources |
|
|
|
• ASP.NET WebMatrix ASP.NET Web Pages forum, a great place to post questions and get |
|
|
|
answers. |
|
|
|
• How to publish a web application using WebMatrix, an end-to-end tutorial about how to |
|
|
|
find a hosting provider and publish to the Internet. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Tutorial 9: Publishing a Site by Using WebMatrix |
|
|
|
125 |
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|
This page intentionally left blank |
|
|
|
Appendix: Code Listings |
|
|
|
This appendix lists the finished versions of all the pages that you create in this tutorial set. |
|
|
|
Complete Listing for TestRazor Page |
|
|
|
@{ |
|
|
|
// Working with numbers |
|
|
|
var a = 4; |
|
|
|
var b = 5; |
|
|
|
var theSum = a + b; |
|
|
|
// Working with characters (strings) |
|
|
|
var technology = "ASP.NET"; |
|
|
|
var product ="Web Pages"; |
|
|
|
// Working with objects |
|
|
|
var rightNow = DateTime.Now; |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html lang="en"> |
|
|
|
<head> |
|
|
|
<title>Testing Razor Syntax</title> |
|
|
|
<meta charset="utf-8" /> |
|
|
|
<style> |
|
|
|
body {font-family:Verdana; margin-left:50px; margin-top:50px;} |
|
|
|
div {border: 1px solid black; width:50%; margin:1.2em;padding:1em;} |
|
|
|
span.bright {color:red;} |
|
|
|
</style> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Testing Razor Syntax</h1> |
|
|
|
<form method="post"> |
|
|
|
<div> |
|
|
|
<p>The value of <em>a</em> is @a. The value of <em>b</em> is @b. |
|
|
|
<p>The sum of <em>a</em> and <em>b</em> is <strong>@theSum</strong>.</p> |
|
|
|
<p>The product of <em>a</em> and <em>b</em> is <strong>@(a*b)</strong>.</p> |
|
|
|
</div> |
|
|
|
<div> |
|
|
|
<p>The technology is @technology, and the product is @product.</p> |
|
|
|
<p>Together they are <span class="bright">@(technology + " " + product)</span></p> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
127 |
|
|
|
|
|
|
|
|
|
|
|
|
|
</div> |
|
|
|
<div> |
|
|
|
<p>The current date and time is: @rightNow</p> |
|
|
|
<p>The URL of the current page is<br/><br/><code>@Request.Url</code></p> |
|
|
|
</div> |
|
|
|
</form> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for TestRazorPart2 Page |
|
|
|
@{ |
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|
|
var message = "This is the first time you've requested the page."; |
|
|
|
if(IsPost){ |
|
|
|
message = "Now you've submitted the page."; |
|
|
|
} |
|
|
|
var showMessage = false; |
|
|
|
if(Request.QueryString["show"].AsBool() == true){ |
|
|
|
showMessage = true; |
|
|
|
} |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html lang="en"> |
|
|
|
<head> |
|
|
|
<title>Testing Razor Syntax - Part 2</title> |
|
|
|
<meta charset="utf-8" /> |
|
|
|
<style> |
|
|
|
body {font-family:Verdana; margin-left:50px; margin-top:50px;} |
|
|
|
div {border: 1px solid black; width:50%; margin:1.2em;padding:1em;} |
|
|
|
</style> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Testing Razor Syntax - Part 2</h1> |
|
|
|
<form method="post"> |
|
|
|
<div> |
|
|
|
<!--<p>@message</p>--> |
|
|
|
@if(showMessage){ |
|
|
|
<p>@message</p> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
128 |
|
|
|
|
|
|
|
|
|
|
|
|
|
} |
|
|
|
<p><input type="submit" value="Submit" /></p> |
|
|
|
@if(IsPost){ |
|
|
|
<p>You submitted the page at @DateTime.Now</p> |
|
|
|
} |
|
|
|
</div> |
|
|
|
</form> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for TwitterTest Page |
|
|
|
@{ |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html lang="en"> |
|
|
|
<head> |
|
|
|
<meta charset="utf-8" /> |
|
|
|
<title></title> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<div> |
|
|
|
@TwitterGoodies.Search("webmatrix") |
|
|
|
</div> |
|
|
|
<div> |
|
|
|
@TwitterGoodies.FollowButton("microsoft") |
|
|
|
</div> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for Movies Page |
|
|
|
@{ |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var selectedData = db.Query("SELECT * FROM Movies"); |
|
|
|
var grid = new WebGrid(source: selectedData, rowsPerPage: 3); |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html lang="en"> |
|
|
|
<head> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
129 |
|
|
|
|
|
|
|
|
|
<meta charset="utf-8" /> |
|
|
|
<title>Movies</title> |
|
|
|
<style type="text/css"> |
|
|
|
.grid { margin: 4px; border-collapse: collapse; width: 600px; } |
|
|
|
.grid th, .grid td { border: 1px solid #C0C0C0; padding: 5px; } |
|
|
|
.head { background-color: #E8E8E8; font-weight: bold; color: #FFF; } |
|
|
|
.alt { background-color: #E8E8E8; color: #000; } |
|
|
|
</style> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Movies</h1> |
|
|
|
<div> |
|
|
|
@grid.GetHtml( |
|
|
|
tableStyle: "grid", |
|
|
|
headerStyle: "head", |
|
|
|
alternatingRowStyle: "alt", |
|
|
|
columns: grid.Columns( |
|
|
|
grid.Column("Title"), |
|
|
|
grid.Column("Genre"), |
|
|
|
grid.Column("Year") |
|
|
|
) |
|
|
|
) |
|
|
|
</div> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for Movie Page (Updated with Search) |
|
|
|
@{ |
|
|
|
var db = Database.Open("WebPagesMovies") ; |
|
|
|
var selectCommand = "SELECT * FROM Movies"; |
|
|
|
var searchTerm = ""; |
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
|
|
searchTerm = Request.QueryString["searchGenre"]; |
|
|
|
} |
|
|
|
if(!Request.QueryString["searchTitle"].IsEmpty() ) { |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Title LIKE @0"; |
|
|
|
searchTerm = "%" + Request["searchTitle"] + "%"; |
|
|
|
} |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
130 |
|
|
|
|
|
|
|
|
|
var selectedData = db.Query(selectCommand, searchTerm); |
|
|
|
var grid = new WebGrid(source: selectedData, defaultSort: "Genre", |
|
|
|
rowsPerPage:3); |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html lang="en"> |
|
|
|
<head> |
|
|
|
<meta charset="utf-8" /> |
|
|
|
<title>Movies</title> |
|
|
|
<style type="text/css"> |
|
|
|
.grid { margin: 4px; border-collapse: collapse; width: 600px; } |
|
|
|
.grid th, .grid td { border: 1px solid #C0C0C0; padding: 5px; } |
|
|
|
.head { background-color: #E8E8E8; font-weight: bold; color: #FFF; } |
|
|
|
.alt { background-color: #E8E8E8; color: #000; } |
|
|
|
</style> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Movies</h1> |
|
|
|
<form method="get"> |
|
|
|
<div> |
|
|
|
<label for="searchGenre">Genre to look for:</label> |
|
|
|
<input type="text" name="searchGenre" |
|
|
|
value="@Request.QueryString["searchGenre"]" /> |
|
|
|
<input type="Submit" value="Search Genre" /><br/> |
|
|
|
(Leave blank to list all movies.)<br/> |
|
|
|
</div> |
|
|
|
<div> |
|
|
|
<label for="SearchTitle">Movie title contains the following:</label> |
|
|
|
<input type="text" name="searchTitle" |
|
|
|
value="@Request.QueryString["searchTitle"]" /> |
|
|
|
<input type="Submit" value="Search Title" /><br/> |
|
|
|
</div> |
|
|
|
</form> |
|
|
|
<div> |
|
|
|
@grid.GetHtml( |
|
|
|
tableStyle: "grid", |
|
|
|
headerStyle: "head", |
|
|
|
alternatingRowStyle: "alt", |
|
|
|
columns: grid.Columns( |
|
|
|
grid.Column("Title"), |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
131 |
|
|
|
|
|
|
|
|
|
|
|
grid.Column("Genre"), |
|
|
|
grid.Column("Year") |
|
|
|
) |
|
|
|
) |
|
|
|
</div> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for AddMovie Page |
|
|
|
@{ |
|
|
|
Validation.RequireField("title", "You must enter a title"); |
|
|
|
Validation.RequireField("genre", "Genre is required"); |
|
|
|
Validation.RequireField("year", "You haven't entered a year"); |
|
|
|
var title = ""; |
|
|
|
var genre = ""; |
|
|
|
var year = ""; |
|
|
|
if(IsPost && Validation.IsValid()){ |
|
|
|
title = Request.Form["title"]; |
|
|
|
genre = Request.Form["genre"]; |
|
|
|
year = Request.Form["year"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var insertCommand = "INSERT INTO Movies (Title, Genre, Year) " + |
|
|
|
" Values(@0, @1, @2)"; |
|
|
|
db.Execute(insertCommand, title, genre, year); |
|
|
|
Response.Redirect("~/Movies"); |
|
|
|
} |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html> |
|
|
|
<head> |
|
|
|
<meta charset="utf-8" /> |
|
|
|
<title>Add a Movie</title> |
|
|
|
<style type="text/css"> |
|
|
|
.field-validation-error { |
|
|
|
font-weight:bold; |
|
|
|
color:red; |
|
|
|
background-color:yellow; |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
132 |
|
|
|
|
|
|
|
|
|
|
|
|
|
} |
|
|
|
.validation-summary-errors{ |
|
|
|
border:2px dashed red; |
|
|
|
color:red; |
|
|
|
background-color:yellow; |
|
|
|
font-weight:bold; |
|
|
|
margin:12px; |
|
|
|
} |
|
|
|
</style> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Add a Movie</h1> |
|
|
|
@Html.ValidationSummary() |
|
|
|
<form method="post"> |
|
|
|
<fieldset> |
|
|
|
<legend>Movie Information</legend> |
|
|
|
<p><label for="title">Title:</label> |
|
|
|
<input type="text" name="title" value="@Request.Form["title"]" /> |
|
|
|
@Html.ValidationMessage("title") |
|
|
|
<p><label for="genre">Genre:</label> |
|
|
|
<input type="text" name="genre" value="@Request.Form["genre"]" /> |
|
|
|
@Html.ValidationMessage("genre") |
|
|
|
<p><label for="year">Year:</label> |
|
|
|
<input type="text" name="year" value="@Request.Form["year"]" /> |
|
|
|
@Html.ValidationMessage("year") |
|
|
|
<p><input type="submit" name="buttonSubmit" value="Add Movie" /></p> |
|
|
|
</fieldset> |
|
|
|
</form> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for Movie Page (Updated with Edit Links) |
|
|
|
@{ |
|
|
|
var db = Database.Open("WebPagesMovies") ; |
|
|
|
var selectCommand = "SELECT * FROM Movies"; |
|
|
|
var searchTerm = ""; |
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
133 |
|
|
|
|
|
|
|
|
|
|
|
searchTerm = Request.QueryString["searchGenre"]; |
|
|
|
} |
|
|
|
if(!Request.QueryString["searchTitle"].IsEmpty() ) { |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Title LIKE @0"; |
|
|
|
searchTerm = "%" + Request.QueryString["searchTitle"] + "%"; |
|
|
|
} |
|
|
|
var selectedData = db.Query(selectCommand, searchTerm); |
|
|
|
var grid = new WebGrid(source: selectedData, defaultSort: "Genre", |
|
|
|
rowsPerPage:3); |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html lang="en"> |
|
|
|
<head> |
|
|
|
<meta charset="utf-8" /> |
|
|
|
<title>Movies</title> |
|
|
|
<style type="text/css"> |
|
|
|
.grid { margin: 4px; border-collapse: collapse; width: 600px; } |
|
|
|
.grid th, .grid td { border: 1px solid #C0C0C0; padding: 5px; } |
|
|
|
.head { background-color: #E8E8E8; font-weight: bold; color: #FFF; } |
|
|
|
.alt { background-color: #E8E8E8; color: #000; } |
|
|
|
</style> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Movies</h1> |
|
|
|
<form method="get"> |
|
|
|
<div> |
|
|
|
<label for="searchGenre">Genre to look for:</label> |
|
|
|
<input type="text" name="searchGenre" |
|
|
|
value="@Request.QueryString["searchGenre"]" /> |
|
|
|
<input type="Submit" value="Search Genre" /><br/> |
|
|
|
(Leave blank to list all movies.)<br/> |
|
|
|
</div> |
|
|
|
<div> |
|
|
|
<label for="SearchTitle">Movie title contains the |
|
|
|
following:</label> |
|
|
|
<input type="text" name="searchTitle" |
|
|
|
value="@Request.QueryString["searchTitle"]" /> |
|
|
|
<input type="Submit" value="Search Title" /><br/> |
|
|
|
</div> |
|
|
|
</form> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
134 |
|
|
|
|
|
|
|
|
|
|
|
<div> |
|
|
|
@grid.GetHtml( |
|
|
|
tableStyle: "grid", |
|
|
|
headerStyle: "head", |
|
|
|
alternatingRowStyle: "alt", |
|
|
|
columns: grid.Columns( |
|
|
|
grid.Column(format: |
|
|
|
@<a href="~/[email protected]">Edit</a>), |
|
|
|
grid.Column("Title"), |
|
|
|
grid.Column("Genre"), |
|
|
|
grid.Column("Year") |
|
|
|
) |
|
|
|
) |
|
|
|
</div> |
|
|
|
<p> |
|
|
|
<a href="~/AddMovie">Add a movie</a> |
|
|
|
</p> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Page Listing for Edit Movie Page |
|
|
|
@{ |
|
|
|
var title = ""; |
|
|
|
var genre = ""; |
|
|
|
var year = ""; |
|
|
|
var movieId = ""; |
|
|
|
if(!IsPost){ |
|
|
|
//if(!Request.QueryString["ID"].IsEmpty()){ |
|
|
|
if(!Request.QueryString["ID"].IsEmpty() && |
|
|
|
Request.QueryString["ID"].IsInt()) { |
|
|
|
movieId = Request.QueryString["ID"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var dbCommand = "SELECT * FROM Movies WHERE ID = @0"; |
|
|
|
var row = db.QuerySingle(dbCommand, movieId); |
|
|
|
if(row != null) { |
|
|
|
title = row.Title; |
|
|
|
genre = row.Genre; |
|
|
|
year = row.Year; |
|
|
|
} |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
135 |
|
|
|
|
|
|
|
|
|
else{ |
|
|
|
Validation.AddFormError("No movie was selected."); |
|
|
|
// Use the following line instead for versions of ASP.NET |
|
|
|
// Web Pages 2 earlier than the RC release. |
|
|
|
//ModelState.AddFormError("No movie was selected."); |
|
|
|
} |
|
|
|
} |
|
|
|
else{ |
|
|
|
Validation.AddFormError("No movie was selected."); |
|
|
|
// Use the following line instead for versions of ASP.NET |
|
|
|
// Web Pages 2 earlierthan the RC release. |
|
|
|
//ModelState.AddFormError("No movie was selected."); |
|
|
|
} |
|
|
|
} |
|
|
|
if(IsPost){ |
|
|
|
Validation.RequireField("title", "You must enter a title"); |
|
|
|
Validation.RequireField("genre", "Genre is required"); |
|
|
|
Validation.RequireField("year", "You haven't entered a year"); |
|
|
|
Validation.RequireField("movieid", "No movie ID was submitted!"); |
|
|
|
title = Request.Form["title"]; |
|
|
|
genre = Request.Form["genre"]; |
|
|
|
year = Request.Form["year"]; |
|
|
|
movieId = Request.Form["movieId"]; |
|
|
|
if(Validation.IsValid()){ |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var updateCommand = "UPDATE Movies " + |
|
|
|
" SET Title=@0, Genre=@1, Year=@2 WHERE Id=@3"; |
|
|
|
db.Execute(updateCommand, title, genre, year, movieId); |
|
|
|
Response.Redirect("~/Movies"); |
|
|
|
} |
|
|
|
} |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html> |
|
|
|
<head> |
|
|
|
<meta charset="utf-8" /> |
|
|
|
<title>Edit a Movie</title> |
|
|
|
<style> |
|
|
|
.validation-summary-errors{ |
|
|
|
border:2px dashed red; |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
136 |
|
|
|
|
|
|
|
|
|
|
|
color:red; |
|
|
|
font-weight:bold; |
|
|
|
margin:12px; |
|
|
|
} |
|
|
|
</style> |
|
|
|
</head> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Edit a Movie</h1> |
|
|
|
@Html.ValidationSummary() |
|
|
|
<form method="post"> |
|
|
|
<fieldset> |
|
|
|
<legend>Movie Information</legend> |
|
|
|
<p><label for="title">Title:</label> |
|
|
|
<input type="text" name="title" value="@title" /></p> |
|
|
|
<p><label for="genre">Genre:</label> |
|
|
|
<input type="text" name="genre" value="@genre" /></p> |
|
|
|
<p><label for="year">Year:</label> |
|
|
|
<input type="text" name="year" value="@year" /></p> |
|
|
|
<input type="hidden" name="movieid" value="@movieId" /> |
|
|
|
<p><input type="submit" name="buttonSubmit" value="Submit Changes" /></p> |
|
|
|
</fieldset> |
|
|
|
</form> |
|
|
|
<p><a href="~/Movies">Return to movie listing</a></p> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for Movie Page (Updated with Delete Links) |
|
|
|
@{ |
|
|
|
var db = Database.Open("WebPagesMovies") ; |
|
|
|
var selectCommand = "SELECT * FROM Movies"; |
|
|
|
var searchTerm = ""; |
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
|
|
searchTerm = Request.QueryString["searchGenre"]; |
|
|
|
} |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
137 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
if(!Request.QueryString["searchTitle"].IsEmpty() ) { |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Title LIKE @0"; |
|
|
|
searchTerm = "%" + Request.QueryString["searchTitle"] + "%"; |
|
|
|
} |
|
|
|
var selectedData = db.Query(selectCommand, searchTerm); |
|
|
|
var grid = new WebGrid(source: selectedData, defaultSort: "Genre", |
|
|
|
rowsPerPage:3); |
|
|
|
} |
|
|
|
<!DOCTYPE html> |
|
|
|
<html lang="en"> |
|
|
|
<head> |
|
|
|
<meta charset="utf-8" /> |
|
|
|
<title>Movies</title> |
|
|
|
<style type="text/css"> |
|
|
|
.grid { margin: 4px; border-collapse: collapse; width: 600px; } |
|
|
|
.grid th, .grid td { border: 1px solid #C0C0C0; padding: 5px; } |
|
|
|
.head { background-color: #E8E8E8; font-weight: bold; color: #FFF; } |
|
|
|
.alt { background-color: #E8E8E8; color: #000; } |
|
|
|
</style> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Movies</h1> |
|
|
|
<form method="get"> |
|
|
|
<div> |
|
|
|
<label for="searchGenre">Genre to look for:</label> |
|
|
|
<input type="text" name="searchGenre" |
|
|
|
value="@Request.QueryString["searchGenre"]" /> |
|
|
|
<input type="Submit" value="Search Genre" /><br/> |
|
|
|
(Leave blank to list all movies.)<br/> |
|
|
|
</div> |
|
|
|
<div> |
|
|
|
<label for="SearchTitle">Movie title contains the following:</label> |
|
|
|
<input type="text" name="searchTitle" |
|
|
|
value="@Request.QueryString["searchTitle"]" /> |
|
|
|
<input type="Submit" value="Search Title" /><br/> |
|
|
|
</div> |
|
|
|
</form> |
|
|
|
<div> |
|
|
|
@grid.GetHtml( |
|
|
|
tableStyle: "grid", |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
138 |
|
|
|
|
|
|
|
|
|
|
|
headerStyle: "head", |
|
|
|
alternatingRowStyle: "alt", |
|
|
|
columns: grid.Columns( |
|
|
|
grid.Column(format: @<a href="~/[email protected]">Edit</a>), |
|
|
|
grid.Column("Title"), |
|
|
|
grid.Column("Genre"), |
|
|
|
grid.Column("Year"), |
|
|
|
grid.Column(format: |
|
|
|
@<a href="~/[email protected]">Delete</a>) |
|
|
|
) |
|
|
|
) |
|
|
|
</div> |
|
|
|
<p> |
|
|
|
<a href="~/AddMovie">Add a movie</a> |
|
|
|
</p> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for DeleteMovie Page |
|
|
|
@{ |
|
|
|
var title = ""; |
|
|
|
var genre = ""; |
|
|
|
var year = ""; |
|
|
|
var movieId = ""; |
|
|
|
if(!IsPost){ |
|
|
|
if(!Request.QueryString["ID"].IsEmpty() && |
|
|
|
Request.QueryString["ID"].IsInt()){ |
|
|
|
movieId = Request.QueryString["ID"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var dbCommand = "SELECT * FROM Movies WHERE ID = @0"; |
|
|
|
var row = db.QuerySingle(dbCommand, movieId); |
|
|
|
if(row != null) { |
|
|
|
title = row.Title; |
|
|
|
genre = row.Genre; |
|
|
|
year = row.Year; |
|
|
|
} |
|
|
|
else{ |
|
|
|
Validation.AddFormError("No movie was found for that ID."); |
|
|
|
// If you are using a version of ASP.NET Web Pages 2 that's |
|
|
|
// earlier than the RC release, comment out the preceding |
|
|
|
// statement and uncomment the following one. |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
139 |
|
|
|
|
|
//ModelState.AddFormError("No movie was found for that ID."); |
|
|
|
} |
|
|
|
} |
|
|
|
else{ |
|
|
|
Validation.AddFormError("No movie was found for that ID."); |
|
|
|
// If you are using a version of ASP.NET Web Pages 2 that's |
|
|
|
// earlier than the RC release, comment out the preceding |
|
|
|
// statement and uncomment the following one. |
|
|
|
//ModelState.AddFormError("No movie was found for that ID."); |
|
|
|
} |
|
|
|
} |
|
|
|
if(IsPost && !Request["buttonDelete"].IsEmpty()){ |
|
|
|
movieId = Request.Form["movieId"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var deleteCommand = "DELETE FROM Movies WHERE ID = @0"; |
|
|
|
db.Execute(deleteCommand, movieId); |
|
|
|
Response.Redirect("~/Movies"); |
|
|
|
} |
|
|
|
} |
|
|
|
<html> |
|
|
|
<head> |
|
|
|
<title>Delete a Movie</title> |
|
|
|
</head> |
|
|
|
<body> |
|
|
|
<h1>Delete a Movie</h1> |
|
|
|
@Html.ValidationSummary() |
|
|
|
<p><a href="~/Movies">Return to movie listing</a></p> |
|
|
|
<form method="post"> |
|
|
|
<fieldset> |
|
|
|
<legend>Movie Information</legend> |
|
|
|
<p><span>Title:</span> |
|
|
|
<span>@title</span></p> |
|
|
|
<p><span>Genre:</span> |
|
|
|
<span>@genre</span></p> |
|
|
|
<p><span>Year:</span> |
|
|
|
<span>@year</span></p> |
|
|
|
<input type="hidden" name="movieid" value="@movieId" /> |
|
|
|
<p><input type="submit" name="buttonDelete" value="Delete Movie" /></p> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
140 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
</fieldset> |
|
|
|
<p><a href="~/Movies">Return to movie listing</a></p> |
|
|
|
</form> |
|
|
|
</body> |
|
|
|
</html> |
|
|
|
Complete Listing for Movie Page (Updated to Use a Layout Page) |
|
|
|
@{ |
|
|
|
Layout = "~/_Layout.cshtml"; |
|
|
|
Page.Title = "List Movies"; |
|
|
|
var db = Database.Open("WebPagesMovies") ; |
|
|
|
var selectCommand = "SELECT * FROM Movies"; |
|
|
|
var searchTerm = ""; |
|
|
|
if(!Request.QueryString["searchGenre"].IsEmpty() ) { |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Genre = @0"; |
|
|
|
searchTerm = Request.QueryString["searchGenre"]; |
|
|
|
} |
|
|
|
if(!Request.QueryString["searchTitle"].IsEmpty() ) { |
|
|
|
selectCommand = "SELECT * FROM Movies WHERE Title LIKE @0"; |
|
|
|
searchTerm = "%" + Request.QueryString["searchTitle"] + "%"; |
|
|
|
} |
|
|
|
var selectedData = db.Query(selectCommand, searchTerm); |
|
|
|
var grid = new WebGrid(source: selectedData, defaultSort: "Genre", |
|
|
|
rowsPerPage:3); |
|
|
|
} |
|
|
|
<h2>List Movies</h2> |
|
|
|
<form method="get"> |
|
|
|
<div> |
|
|
|
<label for="searchGenre">Genre to look for:</label> |
|
|
|
<input type="text" name="searchGenre" |
|
|
|
value="@Request.QueryString["searchGenre"]" /> |
|
|
|
<input type="Submit" value="Search Genre" /><br/> |
|
|
|
(Leave blank to list all movies.)<br/> |
|
|
|
</div> |
|
|
|
<div> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
141 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<label for="SearchTitle">Movie title contains the following:</label> |
|
|
|
<input type="text" name="searchTitle" |
|
|
|
value="@Request.QueryString["searchTitle"]" /> |
|
|
|
<input type="Submit" value="Search Title" /><br/> |
|
|
|
</div> |
|
|
|
</form> |
|
|
|
<div> |
|
|
|
@grid.GetHtml( |
|
|
|
tableStyle: "grid", |
|
|
|
headerStyle: "head", |
|
|
|
alternatingRowStyle: "alt", |
|
|
|
columns: grid.Columns( |
|
|
|
grid.Column(format: @<a href="~/[email protected]">Edit</a>), |
|
|
|
grid.Column("Title"), |
|
|
|
grid.Column("Genre"), |
|
|
|
grid.Column("Year"), |
|
|
|
grid.Column(format: @<a href="~/[email protected]">Delete</a>) |
|
|
|
) |
|
|
|
) |
|
|
|
</div> |
|
|
|
<p><a href="~/AddMovie">Add a movie</a></p> |
|
|
|
Complete Page Listing for Add Movie Page (Updated for Layout) |
|
|
|
@{ |
|
|
|
Layout = "~/_Layout.cshtml"; |
|
|
|
Page.Title = "Add a Movie"; |
|
|
|
Validation.RequireField("title", "You must enter a title"); |
|
|
|
Validation.RequireField("genre", "Genre is required"); |
|
|
|
Validation.RequireField("year", "You haven't entered a year"); |
|
|
|
var title = ""; |
|
|
|
var genre = ""; |
|
|
|
var year = ""; |
|
|
|
if(IsPost){ |
|
|
|
if(Validation.IsValid()){ |
|
|
|
title = Request.Form["title"]; |
|
|
|
genre = Request.Form["genre"]; |
|
|
|
year = Request.Form["year"]; |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
142 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var insertCommand = "INSERT INTO Movies (Title, Genre, Year) " + |
|
|
|
" VALUES(@0, @1, @2)"; |
|
|
|
db.Execute(insertCommand, title, genre, year); |
|
|
|
Response.Redirect("~/Movies"); |
|
|
|
} |
|
|
|
} |
|
|
|
} |
|
|
|
<h2>Add a Movie</h2> |
|
|
|
@Html.ValidationSummary() |
|
|
|
<form method="post"> |
|
|
|
<fieldset> |
|
|
|
<legend>Movie Information</legend> |
|
|
|
<p><label for="title">Title:</label> |
|
|
|
<input type="text" name="title" value="@Request.Form["title"]" /> |
|
|
|
@Html.ValidationMessage("title") |
|
|
|
<p><label for="genre">Genre:</label> |
|
|
|
<input type="text" name="genre" value="@Request.Form["genre"]" /> |
|
|
|
@Html.ValidationMessage("genre") |
|
|
|
<p><label for="year">Year:</label> |
|
|
|
<input type="text" name="year" value="@Request.Form["year"]" /> |
|
|
|
@Html.ValidationMessage("year") |
|
|
|
<p><input type="submit" name="buttonSubmit" value="Add Movie" /></p> |
|
|
|
</fieldset> |
|
|
|
</form> |
|
|
|
Complete Page Listing for Delete Movie Page (Updated for Layout) |
|
|
|
@{ |
|
|
|
Layout = "~/_Layout.cshtml"; |
|
|
|
Page.Title = "Delete a Movie"; |
|
|
|
var title = ""; |
|
|
|
var genre = ""; |
|
|
|
var year = ""; |
|
|
|
var movieId = ""; |
|
|
|
if(!IsPost){ |
|
|
|
if(!Request.QueryString["ID"].IsEmpty() && |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
143 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Request.QueryString["ID"].AsInt() > 0){ |
|
|
|
movieId = Request.QueryString["ID"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var dbCommand = "SELECT * FROM Movies WHERE ID = @0"; |
|
|
|
var row = db.QuerySingle(dbCommand, movieId); |
|
|
|
if(row != null) { |
|
|
|
title = row.Title; |
|
|
|
genre = row.Genre; |
|
|
|
year = row.Year; |
|
|
|
} |
|
|
|
else{ |
|
|
|
Validation.AddFormError("No movie was found for that ID."); |
|
|
|
// If you are using a version of ASP.NET Web Pages 2 that's |
|
|
|
// earlier than the RC release, comment out the preceding |
|
|
|
// statement and uncomment the following one. |
|
|
|
//ModelState.AddFormError("No movie was found for that ID."); |
|
|
|
} |
|
|
|
} |
|
|
|
else{ |
|
|
|
Validation.AddFormError("No movie was found for that ID."); |
|
|
|
// If you are using a version of ASP.NET Web Pages 2 that's |
|
|
|
// earlier than the RC release, comment out the preceding |
|
|
|
// statement and uncomment the following one. |
|
|
|
//ModelState.AddFormError("No movie was found for that ID."); |
|
|
|
} |
|
|
|
} |
|
|
|
if(IsPost && !Request["buttonDelete"].IsEmpty()){ |
|
|
|
movieId = Request.Form["movieId"]; |
|
|
|
var db = Database.Open("WebPagesMovies"); |
|
|
|
var deleteCommand = "DELETE FROM Movies WHERE ID = @0"; |
|
|
|
db.Execute(deleteCommand, movieId); |
|
|
|
Response.Redirect("~/Movies"); |
|
|
|
} |
|
|
|
} |
|
|
|
<h2>Delete a Movie</h2> |
|
|
|
@Html.ValidationSummary() |
|
|
|
<p><a href="~/Movies">Return to movie listing</a></p> |
|
|
|
<form method="post"> |
|
|
|
<fieldset> |
|
|
|
<legend>Movie Information</legend> |
|
|
|
<p><span>Title:</span> |
|
|
|
Introducing ASP.NET Web Pages 2 |
|
|
|
Appendix: Code Listings |
|
|
|
144 |
|
|
|
|
|
|
|
|
|
<span>@title</span></p> |
|
|
|
<p><span>Genre:</span> |
|
|
|
<span>@genre</span></p> |
|
|
|
<p><span>Year:</span> |
|
|
|
<span>@year</span></p> |
|
|
|
<input type="hidden" name="movieid" value="@movieId" /> |
|
|
|
<p><input type="submit" name="buttonDelete" value="Delete Movie" /></p> |
|
|
|
</fieldset> |
|
|
|
</form> |
|
|
|
Complete Page Listing for Edit Movie Page (Updated for Layout) |
|
|
|
@{ |
|
|
|
Layout = "~/_Layout.cshtml"; |
|
|
|
Page.Title = "Edit a Movie"; |
|
|
|
var title = ""; |
|
|
|
var genre = ""; |
|
|
|
var year = ""; |
|
|
|
var movieId = ""; |
|
|
|
if(!IsPost){ |
|
|
|
if(!Request.QueryString["ID"].IsEmpty() && |
|
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Request.QueryString["ID"].IsInt()) { |
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movieId = Request.QueryString["ID"]; |
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var db = Database.Open("WebPagesMovies"); |
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var dbCommand = "SELECT * FROM Movies WHERE ID = @0"; |
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var row = db.QuerySingle(dbCommand, movieId); |
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if(row != null) { |
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title = row.Title; |
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genre = row.Genre; |
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year = row.Year; |
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} |
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else{ |
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Validation.AddFormError("No movie was selected."); |
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// If you are using a version of ASP.NET Web Pages 2 that's |
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// earlier than the RC release, comment out the preceding |
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// statement and uncomment the following one. |
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//ModelState.AddFormError("No movie was selected."); |
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Introducing ASP.NET Web Pages 2 |
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Appendix: Code Listings |
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145 |
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} |
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} |
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else{ |
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Validation.AddFormError("No movie was selected."); |
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// If you are using a version of ASP.NET Web Pages 2 that's |
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// earlier than the RC release, comment out the preceding |
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// statement and uncomment the following one. |
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//ModelState.AddFormError("No movie was selected."); |
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} |
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} |
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if(IsPost){ |
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Validation.RequireField("title", "You must enter a title"); |
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Validation.RequireField("genre", "Genre is required"); |
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Validation.RequireField("year", "You haven't entered a year"); |
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Validation.RequireField("movieid", "No movie ID was submitted!"); |
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title = Request.Form["title"]; |
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genre = Request.Form["genre"]; |
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year = Request.Form["year"]; |
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movieId = Request.Form["movieId"]; |
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if(Validation.IsValid()){ |
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var db = Database.Open("WebPagesMovies"); |
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var updateCommand = "UPDATE Movies " + |
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" SET Title=@0, Genre=@1, Year=@2 WHERE Id=@3"; |
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db.Execute(updateCommand, title, genre, year, movieId); |
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Response.Redirect("~/Movies"); |
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} |
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} |
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} |
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<h2>Edit a Movie</h2> |
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@Html.ValidationSummary() |
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<form method="post"> |
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<fieldset> |
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<legend>Movie Information</legend> |
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<p><label for="title">Title:</label> |
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<input type="text" name="title" value="@title" /></p> |
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<p><label for="genre">Genre:</label> |
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<input type="text" name="genre" value="@genre" /></p> |
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Introducing ASP.NET Web Pages 2 |
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Appendix: Code Listings |
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146 |
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<p><label for="year">Year:</label> |
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<input type="text" name="year" value="@year" /></p> |
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<input type="hidden" name="movieid" value="@movieId" /> |
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<p><input type="submit" name="buttonSubmit" value="Submit Changes" /></p> |
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</fieldset> |
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</form> |
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<p><a href="~/Movies">Return to movie listing</a></p> |
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Introducing ASP.NET Web Pages 2 |
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Appendix: Code Listings |
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147 |
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