UrlHelper.Action includes undesired additional parameters

Question

I have a method in the controller ApplicationsController, in which I need to get the base URL for an action method:

public ActionResult MyAction(string id)
{
    var url = Url.Action("MyAction", "Applications");
    ...
}

The problem is that this includes the string id from the current route data, when I need the URL without (the URL is used to fetch content from a CMS on a URL-based lookup).

I have tried passing null and new { } as the routeValues parameter to no avail.

The matching route is as follows (above all other routes):

routes.MapLowercaseRoute(
    name: "Applications",
    url: "applications/{action}/{id}",
    defaults: new { controller = "Applications",
                    action = "Index", id = UrlParameter.Optional });

I've seen a couple of other questions touch on this but none of them seem to have a viable solution. At present, I am resorting to hardcoding the path in the controller; however, I'd like to be able to abstract this into an action filter, so I need to be able to generate the URL.

Is there a clean/conventional way to prevent this behaviour?

Answer 1

Ok, I see the problem. It's something called "Segment variable reuse". When generating the routes for outbound URLs, and trying to find values for each of the segment variables in a route’s URL pattern, the routing system will look at the values from the current request. This is a behavior that confuses many programmers and can lead to a lengthy debugging session. The routing system is keen to make a match against a route, to the extent that it will reuse segment variable values from the incoming URL. So I think you have to override the value like Julien suggested :

var url = Url.Action("MyAction", "Applications", new { id = "" })