为什么需要在ASP.NET MVC中的RoutesTable的默认路由中指定控制器和动作？

Question

Why do we have to specify the defaults for the default route?

This is a normal default route:

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

Why can't I just do this:

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

I already specified the action and controller but when I use this way, I get an error. Does anyone know why you have to specify the action and controller in the default route?

Answer 1

Without a default set of parameters, how is routing supposed to know where to send this URL?

/

The defaults let you do that URL, so it knows to use the 'Home' controller's 'Index' method.

Or:

/Articles

In this case, the 'Index' action of the 'Articles' controller would be called. Without those defaults, again, routing has no way to know what to do.