ASP.NET MVC remap Catch-All parameter value and execute another valid route

Question

I'm trying to construct the flexible URL routing.

So the url like

en-US/ctrl/act/1/2

should do the same as

ctrl/act/1/2

and set the culture to en-US.

Now I have achieved that by defining two routes as following:

routes.MapRoute(
    "Ctrl",
    "ctrl/{action}/{group}/{page}",
    new { controller = "Home", action = "Index", group = 1, page = 1 },
    new { group = @"\d+", page = @"\d+" }
    );

routes.MapRoute("CtrlWithCulture",
    "{culture}/ctrl/{action}/{group}/{page}",
    new { culture = "", controller = "Home", action = "Index", group = 1, page = 1 },
    new { culture = "[a-z]{2}-(?:[a-zA-Z]{2,4}-)*(?:[a-zA-Z]{2,4})", group = @"\d+", page = @"\d+" }
    );

I have a base controller that is setting the culture based on the input parameter. But I want to have this functionality by default for all the routes, so I tried something like this.

Global.asax.cs:

routes.MapRoute("RootWithCulture",
    "{culture}/{*rest}",
    new { controller = "Home", action = "Index", culture = "" },
    new { culture = "[a-z]{2}-(?:[a-zA-Z]{2,4}-)*(?:[a-zA-Z]{2,4})" }
    );

MyController.cs 

public class MyController : Controller
{
...
    protected override void OnActionExecuting(ActionExecutingContext context)
    {
     if (!String.IsNullOrEmpty(context.RouteData.Values["culture"].ToStringOrNull()))
     {
      this.SetCulture(String.IsNullOrEmpty(context.RouteData.Values["culture"])
      context.RouteData.Values.Remove("culture");
      // I'm stuck here!
      // I want to try other routes and find and execute the right one...

I'm not sure what would be the right approach to this...

Answer 1

In the end I did it with a custom RoutingModule that looks like this:

public class RewritingRoutingModule : UrlRoutingModule
{
protected string routeNameToRewrite = "rewrite";
public override void PostResolveRequestCache(HttpContextBase context)
{
 RouteData routeData = this.RouteCollection.GetRouteData(context);
 if (routeData != null)
 {
  if (routeData.Values.ContainsKey(routeNameToRewrite))
  {
   // take all route parameters before *rewrite
   IEnumerable<KeyValuePair<string, object>> additionalData = routeData.Values.TakeWhile(item => item.Key != routeNameToRewrite);
   // put route parameter names and values into HttpContextBase.Item collection
   foreach (KeyValuePair<string, object> item in additionalData)
    context.Items.Add(item.Key, item.Value);
   // rewrite the route with *rewrite part only 
   context.RewritePath("~/" + (routeData.Values[routeNameToRewrite] != null ? routeData.Values[routeNameToRewrite].ToString() : ""));
  }
 }
 base.PostResolveRequestCache(context);
}

I placed such a route at the end in Global.asax:

routes.MapRoute("RewritingRoute-Culture", "{culture}/{*rewrite}", new { }, new { culture = @"en-US|de-AT" });

So if this matches, it will append the values to HttpContextBase.Items, and then find another route with controller etc and execute that one.