can not map a route for a specific controller in mvc 4

Question

I have a controller named Registration and an action method in it as the following:

public JsonResult GetReqs(GridSettings gridSettings, int rt)
    {
        ...//whatever

        return Json(jsonData, JsonRequestBehavior.AllowGet);
    }

So I added a route and now my RouteConfig.cs is like this:

public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapRoute(
            name: "RegReq",
            url: "{Registration}/{GetReqs}/{rt}",
            defaults: new { controller = "Registration", action = "GetReqs", rt = UrlParameter.Optional }
        );

        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
        );            
    }
}

However I can't access the rt parameter and the action method GetReqs isn't called(I set a breakpoint on it but nothing happened). Where is the mistake?

Edit: Link example I tried : ~/Registration/GetReqs/1

Answer 1

I think you need to remove the brackets in your first route:

routes.MapRoute(
            name: "RegReq",
            url: "Registration/GetReqs/{rt}",
            defaults: new { controller = "Registration", action = "GetReqs", 
              rt = UrlParameter.Optional }
        );

The default route has {controller} to tell MVC to use the string in that section of the url as the controller name. You know the controller, so you just need to match the specific string.