How does ASP.NET MVC arbitrate between two identically named views (aspx and razor)?

Using ASP.NET MVC3 I created a new Razor view and gave it the same name as the existing .aspx view that I had been using. I noticed that controller continued to pick up the .aspx view (which has the same name as the action) which is pretty much what I expected. I then renamed the .aspx view 开发者_如何学Goand action picked up the razor .cshtml view.

So if I have two views called myview.aspx and myview.cshtml and an Action called MyView() that does a return View(), it will pick up the myview.aspx view and return that.

How does MVC3 decided which view-type to default to? Is there a way to change this default behavior to prefer a razor view over an .aspx view?

Everything stems down to the order of view engines in the ViewEngines.Engines collection. Here's how the ViewEngines static constructor looks like (as seen with Reflector in ASP.NET MVC 3 RTM):

static ViewEngines()
{
    ViewEngineCollection engines = new ViewEngineCollection();
    engines.Add(new WebFormViewEngine());
    engines.Add(new RazorViewEngine());
    _engines = engines;
}

which explains why WebForms is the preferred view engine.

So you could perform the following grotesque hack in Application_Start to inverse the preference towards Razor :-)

var aspxVe = ViewEngines.Engines[0];
var razorVe = ViewEngines.Engines[1];
ViewEngines.Engines.Clear();
ViewEngines.Engines.Add(razorVe);
ViewEngines.Engines.Add(aspxVe);

I would imagine its down to the order in which view engines are registered. Earlier registered view engines will be queried first. If you want to change the order:

ViewEngines.Engines.Insert(0, ...);