Combine ASP.Net MVC with WebForms

For reference I managed to accomplish this task yesterday - add MVC functionality to an existing WebForms website, that is - so thought I would write in case it is of any use to anybody.

People say: "the best way is to rewrite your web forms application as MVC" but there is often no business case for this when the application is well established and has grew over time to be quite a monster (that still works well I might add). In my case, we had been asked to implement a new function into this application - and having been developing in MVC on other projects recently - I wanted to build this new function in MVC. This is what I did:

1. Create a new ASP.NET MVC 4 Application and selected the Empty Template (with Razor)

2. Once loaded, right-clicked References > Browse and then navigated to the Bin folder of my existing website. I then added in the DLL's I was using in the existing site. For reference, I am using AjaxControlToolkit so decided to add in the latest one from NuGet. This should then auto-update the web.config file

3. I then opened up Windows Explorer and navigated to the root folder of my existing website. Using Visual Studio, I then replicated the top-level folder structure of the existing site (minus the Bin folder) resulting in the 2 sites having the same top-level folders (but the new project having the MVC App_Start, Controllers, Models and Views folders also, but not Bin obviously).

4. Once setup, I copied the sub-folders and files from the corresponding top-level folder in Windows Explorer and pasted them into the solution. If you do it the way, the project allows you to copy in sub-folders and content directly, adding existing item via visual studio only copies in files thus saving time. Please note: for the root folder, I did NOT copy in web.config or Global.asax, but copied in all other files (like default.aspx, etc)

5. Once all content was copied, I opened up web.config in the new project and web.config in the existing site. I copied into the new web.config anything specific to the existing website (appSettings, connectionStrings, namespaces, membership info, etc). The same applied to the Global.asax files.

6. I attempted a build and fixed anything I'd missed.

7. Once everything was right (and I had shot down a few Yellow screens of death) I noticed that I got the page not found error when loading default.aspx. This is down to routing, here is the changes I made to the Routing info (located in Global.ascx MVC 3, or App_Start > RouteConfig.cs MVC 4):

   public static void RegisterRoutes(RouteCollection routes)
   {
       routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
   
       // This informs MVC Routing Engine to send any requests for .aspx page to the WebForms engine
       routes.IgnoreRoute("{resource}.aspx/{*pathInfo}");
       routes.IgnoreRoute("{resource}.aspx");
   
       // Important change here: removed 'controller = "Home"' from defaults. This is the key for loading
       // root default page. With default setting removed '/' is NOT matched, so default.aspx will load instead
       routes.MapRoute(
           name: "Default",
           url: "{controller}/{action}/{id}",
           defaults: new { action = "Index", id = UrlParameter.Optional }
       );
   }
   

With all these steps taken, the site loaded and ran as it always did, but I now have a ASP.NET WebForms and MVC hybrid. I am sure there are probably easier ways of accomplishing this task, but I tried other methods and failed. This way took me around 20 minutes and I was up and running... well sat and coding :)

Combining web forms with MVC is entirely possible. See this blog post by Scott Hanselman for an introduction.

• Sharing master pages: see this StackOverflow question
• routing: In ASP.Net 4.0, routing has been enabled for web forms page routes (scottgu's blog)