MVC Route Error: The constraint entry 'Length'

Question

I have a controller called Account with an action with the following signature:

public ActionResult Verify(string userName, Guid authorisationToken);

I have created a link to call this action thus:

/Account/Verify/sachin13/409bdaaa-0b65-4bb8-8695-6e430323d8f8

When I go to this link I get the following error:

The constraint entry 'Length' on the route with URL 'Account/{Verify}/{userName}/{authorisationToken}' must have a string value or be of a type which implements IRouteConstraint.

This is what my RegisterRoutes method looks like in Global.asax:

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

            routes.MapRoute(
                "Default", // Route name
                "{controller}/{action}/{id}", // URL with parameters
                new { controller = "Home", action = "Index", id = UrlParameter.Optional } ,// Parameter defaults
                new[] { "UI.Controllers" }
            );

            routes.MapRoute(
                "AccountVerify",
                "Account/{Verify}/{userName}/{authorisationToken}",
                new { controller = "Account", action = "Verify", userName = "", authorisationToken = "" },
                "UI.Controllers"
            );
        }

Two questions:

1. Am I doing anything out of the ordinary or is my methodology here in line with standard practice?

2. What is the problem here?

Thanks,

Sachin

Answer 1

You should change

"UI.Controllers"

to

new[] { "UI.Controllers" }

in your second route.

If you're specifying only a single string (not an array) then you get wrong overload of MapRoute function - instead of MapRoute(RouteCollection, String, String, Object, String[]) which accept a list of namespaces as last parameter you get MapRoute(RouteCollection, String, String, Object, Object) which expects constraints as last parameter. String "UI.Controllers" is not a correct constraint specification => you get the error.

Also as @Pankaj suggested your custom route should go before default and Verify should be without "{}".

Full code:

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

        routes.MapRoute(
            "AccountVerify",
            "Account/Verify/{userName}/{authorisationToken}",
            new { controller = "Account", action = "Verify", userName = "", authorisationToken = "" },
            new [] { "UI.Controllers" }
        );

        routes.MapRoute(
            "Default", // Route name
            "{controller}/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Index", id = UrlParameter.Optional } ,// Parameter defaults
            new[] { "UI.Controllers" }
        );
    }