No Route in route table matches the supplied values when redirecting from action filter attribute

Question

I have a localization for 3 languages on my web app, scenario is this: When user opens up the page, URL example.com but I want to make it example.com/en.

I am trying to achieve it by using RedirectToRouteResult but on the first try when I open the page, I get error. I have taken the mechanism from this article

The main reason why I am trying to achieve this is the user-level defined culture info, so that when user from one country sets his/her language, his/her won't have to re-do it every time they enter the page, since I am storing the data in cache and database; And OutputCache So that when someone enters the page they won't face other users rendered page which might not the default language for the new user.

public class InternationalizationAttribute : ActionFilterAttribute {
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
    // This is a dummy constraint, if the culture is zz, it means that URL does not contain correct culture
    bool redirectToLanguagedVersion = filterContext.RouteData.Values["culture"].ToString() == "zz"; 
    string language = "en", culture = "GB";

    if (redirectToLanguagedVersion)
    {
        if (filterContext.HttpContext.User.Identity.IsAuthenticated)
        {
            var user = IdentityManager.GetUser(filterContext.HttpContext.User.Identity.GetUserId());
            language = user.CultureInfoLanguage ?? language;
            culture = user.CultureInfoCulture ?? culture;
        }
        else
        {
            language = filterContext.RequestContext.HttpContext.Cache["UserCultureInfoLanguage"]?.ToString() ?? language;
            culture = filterContext.RequestContext.HttpContext.Cache["UserCultureInfoCulture"]?.ToString() ?? culture;
        }

        RouteValueDictionary values = filterContext.RouteData.Values;
        values.Remove("culture");
        values.Add("culture", culture);
        filterContext.Result = new RedirectToRouteResult("DefaultWithCulture", values); // Issue hits here
    }
    else
    {
        // ... Define the culture user should use and update cache/db if needed

        Thread.CurrentThread.CurrentCulture = CultureInfo.GetCultureInfo(string.Format("{0}-{1}", language, culture));
        Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo(string.Format("{0}-{1}", language, culture));
    }
}}

And this is RouteConfig

public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        // Call to register your localized and default attribute routes
        routes.MapLocalizedMvcAttributeRoutes(
            urlPrefix: "{culture}/",
            constraints: new { culture = new CultureConstraint(defaultCulture: "zz", pattern: "[a-z]{2}") }
        );

        routes.MapRoute(
            name: "DefaultWithCulture",
            url: "{culture}/{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional },
            constraints: new { culture = new CultureConstraint(defaultCulture: "zz", pattern: "[a-z]{2}") }
        );

        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { culture = "zz", controller = "Home", action = "Index", id = UrlParameter.Optional }
        );

        routes.MapRoute(
            name: "TourWithCulture",
            url: "{culture}/{controller}/{action}/{id}/{title}",
            defaults: new { controller = "Tours", action = "Explore", id = UrlParameter.Optional, title = UrlParameter.Optional },
            constraints: new { culture = new CultureConstraint(defaultCulture: "zz", pattern: "[a-z]{2}") }
        );

        routes.MapRoute(
            name: "Tour",
            url: "{controller}/{action}/{id}/{title}",
            defaults: new { controller = "Tours", action = "Explore", id = UrlParameter.Optional, title = UrlParameter.Optional },
            constraints: new { culture = new CultureConstraint(defaultCulture: "zz", pattern: "[a-z]{2}") }
        );
    }
}

Answer 1

The reason why you are getting the exception is due to the fact you are not supplying matching values that are needed to build the URL. To build a URL you need to supply all of the required values (and the optional ones if needed). But additional values will cause it not to match.

RouteValueDictionary values = filterContext.RouteData.Values;
values.Remove("culture");
values.Add("culture", culture);
filterContext.Result = new RedirectToRouteResult("DefaultWithCulture", values);

Controller and action are always required. So, for this route you need to pass:

1. culture
2. controller
3. action
4. id (optional)

This means that if your route value collection has more than this (such as title), it will not match DefaultWithCulture. Note that DefaultWithCulture is an extra set of criteria for the route, but you still must pass all of the required route values in order to match it.

That said, you should never pass a route name to RedirectToRouteResult when using routing based on this answer because there are in fact 2 routes that represent the possible matches - DefaultWithCulture and Default in this case. You have to remove the extra name criteria for the match, otherwise it will not be possible to match Default.

RouteValueDictionary values = filterContext.RouteData.Values;
values.Remove("culture");
values.Add("culture", culture);
filterContext.Result = new RedirectToRouteResult(values);