Ambient values in mvc2.net routing

Question

I have following two routes registered in my global.asax file

routes.MapRoute(
    \"strict\",
    \"{controller}.mvc/{docid}/{action}/{id}\",
          


        

Answer 1

This is such a frustrating problem and I would venture to say that it is even a bug in ASP.Net MVC. Luckily it's an easy fix using ActionFilters. If you are using MVC3 then I would just put this as a global attribute to clear out ambient values. I made this attribute discriminatory, but you can change it to clear all attributes.

The assumption here is that by the time the Result is executing (your view most likely), you have already explicitly specified all your ActionLinks and Form Actions. Thus this will execute before they (the links) are evaluated, giving you a new foundation to generate them.

public class ClearAmbientRouteValuesAttribute : ActionFilterAttribute 
{
    private readonly string[] _keys;

    public ClearAmbientRouteValuesAttribute(params string [] keys)
    {
        if (keys == null)
            _keys = new string[0];

        _keys = keys;
    }

    public override void OnResultExecuting(ResultExecutingContext filterContext)
    {
        foreach (var key in _keys) {
            // Why are you sticking around!!!
            filterContext.RequestContext.RouteData.Values.Remove(key);        
        }
    }
}

// Inside your Global.asax
public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
    filters.Add(new HandleErrorAttribute());
    filters.Add(new ClearAmbientRouteValuesAttribute("format"));
}

Hope this helps someone, cause it sure helped me. Thanks for asking this question.