ASP.NET MVC Interim Released

The ASP.NET MVC Team has released an refresh of MVC. To all those that are interested the new Interim Release is posted at:

http://www.codeplex.com/aspnet/Release/ProjectReleases.aspx?ReleaseId=12640

The new release seems to rely on a non-CodePlex open source project.  Is this the first sign of Microsoft's commitment to open source?

The Release Notes have a lot of good information about new features and bug fixed included in this release:

This CodePlex refresh of the ASP.NET MVC source code includes a number of key changes and refactorings.
To see a full list of API changes, take a look at the attached zip file produced using
Framework Design Studio.

MVC Changes Since Preview 2

  • Action methods on Controllers now by default return an ActionResult instance, instead of void.
    • This ActionResult object indicates the result from an action (a view to render, a URL to redirect to, another action/route to execute, etc).
    • Each "result" is a type that inherits from ActionResult. To render a view, return a RenderViewResult instance.


  • The RenderView(), RedirectToAction(), and Redirect() helper methods on the Controller base class now return typed ActionResult objects (which you can further manipulate or return back from action methods).
  • The RenderView() helper method can now be called without having to explicitly pass in the name of the view template you want to render.

    • When you omit the template name the RenderView() method will by default use the name of the action method to determine the view template to render.
    • So calling RenderView() with no parameters inside the About() action method is now the same as explicitly writing RenderView('About').


  • Introduced a new IActionFilter interface for action filters. ActionFilterAttribute implements IActionFilter.
  • Action Filters now have four methods they can implement representing four possible interception points.

    • OnActionExecuting which occurs just before the action method is called.
    • OnActionExecuted which occurs after the action method is called, but before the result is executed (aka before the view is rendered in common scenarios).
    • OnResultExecuting which occurs just before the result is executed (aka before the view is rendered in common scenarios).
    • OnResultExecuted which occurs after the result is executed (aka after the view is rendered in common scenarios).
    • NOTE: The OnResult* methods will not be called if an exception is not handled during the invoking of the OnAction* methods or the action method itself.


  • Added a MapRoute extension method (extension on RouteCollection) for use in declaring MVC routes in a simpler fashion.

NOTE: It is pretty easy to update existing Controller classes built with Preview 2 to use this new pattern (just change void to ActionResult and add a return statement in front of any RenderView or RedirectToAction helper method calls).

Routing changes since Preview 2

  • URLs may contain any literal (except for /) as a separator between URL parameters. For example, instead of {action}.{format} you can now have {action}-{format}. For more details on changes, see this post.
  • Routing is ignored for files that exist on disk by default. This can be overriden by setting the RouteTable.Routes.RouteExistingFiles property to true (it is false by default).

Nick Berardi

Entrepreneur, Microsoft MVP, ASPInsider, co-founder and CTO of @CaddioApp, Father, and @SeriouslyOpen host