MSDN Magazine - March 2008 - (Page 48)

Figure 7 Editing the Home Page leave them out of the URL and still have my request mapped to the correct controller and action. One more thing to note: remember that I said “add to the top of the table”? If you put it at the bottom, you’ll instead get an error. Routing works on a first come, first served basis. When processing URLs, the routing system walks the table from top to bottom, and the first route to match wins. In this case, the default route “[controller]/[action]/[id]” matches because there are default values for the action and ID. Thus, it goes looking for ChrisController, and since I don’t have a controller I get an error. Let’s start off with the basic display of a wiki page. To do this, I created a new class named WikiPageController. I then added an action named ShowPage. The WikiPageController started out looking like Figure 8. The ShowPage method is pretty straightforward. The WikiSpace and WikiPage classes represent a set of wiki pages and a specific page (and its revisions), respectively. This action just loads up the model and calls RenderView. But what’s that “new WikiPageViewData” line in there? My previous example demonstrated one way to pass data from the controller to the view: the ViewData dictionary. Dictionaries are convenient, but they’re also dangerous. They can contain absolutely anything, you don’t get any IntelliSense® for the contents, and because the ViewData dictionary is of type Dictionary to consume its contents you have to cast everything. When you know what data you will need in the view, you can instead pass strongly typed ViewData object. In my case, I created a simple object, WikiPageViewData, as shown in Figure 9. This object carries the wiki page information to the view along with a Figure 8 WikiPageController Implementation of ShowPage public class WikiPageController : Controller { ISpaceRepository repository; public ISpaceRepository Repository { get { if (repository == null) { repository = new FileBasedSpaceRepository( Request.MapPath(“~/WikiPages”)); } return repository; } } set { repository = value; } A Bigger Example Now that I’ve demonstrated the basics of the MVC Framework, I’d like to show you a larger example that does more than just display a string. A wiki is a Web site that can be edited in the browser. Pages can be added or edited easily. I’ve written a small sample wiki using the MVC Framework. The “Edit this page” screen is shown in Figure 7. You can check out the code download for this article to see how the underlying wiki logic is implemented. Right now I want to concentrate on how the MVC Framework made it easy to get the wiki onto the Web. I started out by designing my URL structure. I wanted the following: • /[pagename] displays the page with that name. • /[pagename]?version=n shows the requested version of the page, where 0 = the current version, 1 = the previous one, and so on. • /Edit/[pagename] opens the editing screen for that page. • /CreateNewVersion/[pagename] is the URL that is posted to in order to submit an edit. 48 msdnmagazine ASP.NET MVC [ControllerAction] public void ShowPage(string pageName, int? version) { WikiSpace space = new WikiSpace(Repository); WikiPage page = space.GetPage(pageName); RenderView(“showpage”, new WikiPageViewData { Name = pageName, Page = page, Version = version ?? 0 }); } }

Table of Contents Feed for the Digital Edition of MSDN Magazine - March 2008

MSDN Magazine - March 2008 Contents Toolbox CLR Inside Out Data Points Advanced Basics Office Space Introducing ASP.NET MVC Loosen Up CI Server Performance Office Development Test Run Security Briefs Extreme ASP.NET Foundations .NET Matters {End Bracket}

MSDN Magazine - March 2008

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