How to redirect to a dynamic login URL in ASP.NET MVC

In the RTM version of ASP.NET MVC, the Cancel property is missing. This code works with ASP.NET MVC RTM:

using System;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Resources;

namespace ePegasus.Web.ActionFilters
{
    public class CustomAuthorize : AuthorizeAttribute
    {
        public override void OnAuthorization(AuthorizationContext filterContext)
        {
            base.OnAuthorization(filterContext);
            if (filterContext.Result is HttpUnauthorizedResult)
            {
                filterContext.Result = new RedirectToRouteResult(
                    new System.Web.Routing.RouteValueDictionary
                        {
                                { "langCode", filterContext.RouteData.Values[ "langCode" ] },
                                { "controller", "Account" },
                                { "action", "Login" },
                                { "ReturnUrl", filterContext.HttpContext.Request.RawUrl }
                        });
            }
        }
    }
}

Edit: You may want to disable the default forms authentication loginUrl in web.config – in case somebody forgets you have a custom attribute and uses the built in [Authorize] attribute by mistake.

Modify the value in web.config:

 <forms loginUrl="~/Account/ERROR" timeout="2880" />

Then make an action method ‘ERROR’ that logs an error and redirects the user to the most generic login page you have.