Route value removed but still added as query string parameter - asp.net-mvc

Question

I am extending a model to include a link property. It is based on other properties within it to generate a link:
public partial class MyModelType
{
public string FilterLink
{
get
{
var u = new UrlHelper(HttpContext.Current.Request.RequestContext);
var route = new RouteValueDictionary(u.RequestContext.RouteData.Values);
route.Remove("other");
route.Add("other", null);
route.Add("id", this.Id);
return u.Action("Index", "ControllerName", route);
}
}
}
The link generated is /ControllerName/1?other=2. If I get rid of the route.Remove("other") I get the link based on the mapped route: /ControllerName/1/2. How can I prevent it being used as a query string parameter when it is removed from the route? The UrlHelper seems to be adding it somehow, even though it is not a route value.

Answer 1

Check your routing configuration.
MVCs routing will append any unkown parts of your route in that way, so as long as you define it up front it should work just fine.
You probably just have this:
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
Try adding the option like this:
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}/{option}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional, option = UrlParameter.Optional }
);

Answer 2

The issue is discussed here: http://erraticdev.blogspot.com/2011/03/removing-route-values-from-linksurls-in.html
However, the blogs proposal is convoluted compared with a simple solution in the comments: add "other = null as object" to the defaults values on your DEFAULT route.
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional, other = null as object }
);