How can host name be included in MVC2 route mapping?

Question

I've got 3 domain names all pointed at the same MVC2 application. What I've got now is the homecontroller acting as a traffic cop and redirecting to controllers and views for the specific host name. But I don't like the URI result this causes...

ex: www.webhost1.com/webhost1/imagegallery www.webhost2.com/webhost2/imagegallery

I'd prefer to have:

www.webhost1.com/imagegallery

Is there a way to define the routes in global.asax that would include the host name in the routing evaluation so that the URI looks less redundant?

Answer 1

Aha!, it took a bit of fiddling (and a peak in and old book) but I think I've solved it.

You need to create a custom route constraint. This is the one I made quickly:

 public class hostnameConstraint : IRouteConstraint
    {
        protected string _hostname;

        public hostnameConstraint (string hostname)
        {
            _hostname = hostname;
        }

        bool IRouteConstraint.Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
        {
            if (httpContext.Request.Url.Host == _hostname)
                return true;
            return false;
        }
    }

Then you simply add it to your routes and specify which hostname you want the route to apply to. like so:

routes.MapRoute(
            "ImageGallery", "{controller}/{action}",
            new { controller = "Home", action = "Index"},
            new { hostname = new hostnameConstraint("webhost1.com") }
        );

routes.MapRoute(
            "ImageGallery", "{controller}/{action}",
            new { controller = "Home", action = "Index"},
            new { hostname = new hostnameConstraint("webhost2.com") }
        );

and so on and so forth. I don't know how your routes are layed out, but the point is that now you can have seperate routes for the hostnames. Which should enable you to do what you're after.