Url.Action does not give the expected result. Unwanted route values remain

Question

I have a MVC3 app with several routes. Two of them are defined like this:

routes.MapRoute(
  null,
  "System/{name}", // URL with parameters
  new { controller = "Systems", action = "Index" } // Parameter defaults
);
routes.MapRoute(
  null,
  "Carrier/{name}", // URL with parameters
  new { controller = "Carriers", action = "Index" } // Parameter defaults
);

Now, in my menu I have two links to these routes that are created using Url.Action:

Url.Action("Index","Systems")
Url.Action("Index","Carriers")

Now when i start the application, everything seems fine, and the links in the menu show as /System/ and /Carrier/, and that is the expected value.

However, when i browse to for example /System/MySystem in the web page i would still want the links to point to the same place, but now they point to /System/MySystem and /Carrier/MySystem.

I have tried lots of things to keep the link from using the name from the route value, but to no avail. The strangest case i experienced was when i tried this:

Url.Action("Index","Systems", new{name = (string)null})

Now the link showed up as

/System?name=MySystem

Are there any good way here to make sure that the name value from the route values does not interfer with these links in any way?

Answer 1

As you noticed the Url. helpers reuse the previously given route parameters.

As a workaround (I hope that there is a more elegant solution...) you can remove the name entry from the RouteData.Values in your view:

So before calling you Url.Action in your view:

Url.Action("Index","Systems")
Url.Action("Index","Carriers")

Remove the prefilled name from the RequestContext:

@{
     Request.RequestContext.RouteData.Values.Remove("name");
}

It's also an workaround but if you slightly modify your routes with providing a default null value for your name segment:

routes.MapRoute(
  null,
  "System/{name}", // URL with parameters
  new { controller = "Systems", action = "Index", name = (string)null }
);
routes.MapRoute(
  null,
  "Carrier/{name}", // URL with parameters
  new { controller = "Carriers", action = "Index", name = (string)null }
);

Your original solution ("nulling" the name in the Url.Action) will also work :

@Url.Action("Index", "Systems" , new {name = (string)null} )