Why is the wrong controller being called when I start my ASP.NET MVC2 application?

Question

I have a controller called MetricsController with a single action method:

public class MetricsController
{
  public ActionResult GetMetrics(int id, string period)
  {
    return View("Metrics");
  }
}

I want to route calls to this controller like this:

http://mysite/metrics/getmetrics/123/24h

I've mapped an additional route in my Global.asax.cs like this:

routes.MapRoute(
  "Metrics",
  "{controller}/{action}/{id}/{period}",
  new { controller = "Metrics", action = "GetMetrics", id = 0, period = "" }
);

routes.MapRoute(
  "Default", // Route name
  "{controller}/{action}/{id}", // URL with parameters
  new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

I just added this to the default template project that Visual Studio 2010 creates.

When I run the application, instead of defaulting to the HomeController, it starts in the MetricsController instead.

Why is this happening? There's nothing in the url when I start the application that matches the url pattern specified in the Metrics route.

This is all being tried in Visual Studio 2010 using the built-in web server.

Answer 1

Because it matches first root, of course.

Thing is - when You provide default values - they become optional. If every one of routedata values are optional and route is first - it's guaranteed that it will hit first.

Something like this should work:

routes.MapRoute(
  "Metrics",
  "Metrics/GetMetrics/{id}/{period}",
  //assuming id, period aren't supposed to be optional
  new { controller = "Metrics", action = "GetMetrics" }      
);

routes.MapRoute(
  "Default", // Route name
  "{controller}/{action}/{id}", // URL with parameters
  new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

Answer 2

Remove the defaults from your Metrics route:

routes.MapRoute(
  "Metrics",
  "{controller}/{action}/{id}/{period}",
  new { controller = @"Metrics", action = "GetMetrics"}
);

With the default values MVC is able to map to the GetMetrics action in the Metric controller pretty much any URL that you pass to it.