ASP.NET MVC alternate routing

Question

Is there a way to do regressive route handling in ASP.NET MVC v3?

Here's my business-case example: if given a URL "www.mysite.com/faq/Index", I'd like it to check to see if a route exists for controller "FAQ", action "Index"

routes.MapRoute("Default","{controller}/{action}/{id}",
            new { id = UrlParameter.Optional });

If that cannot be resolved, normally it would throw a 404 error. Instead, I'd like it to use this route:

routes.MapRoute("Content", "Content/{*contentPath}", 
            new { controller = "Content", action = "RenderPageByURL" });

If that fails, then it should return a 404.

I was thinking I could create a custom error handler, but this seems kludgy. Any ideas on where to start? Or is this a truly Bad Idea(TM) and I should go back to the business and tell them to use the correct path to start out with? Thanks.

Edit. To clarify, I'm not trying to see if it matches a route through simple URL matching. I'd like the routing mechanism to be intelligent enough to know if a route will be successful and find a proper controller.

Answer 1

I'm answering my question based on a co-worker's suggestion and the below link (thanks, Josh!):

http://stephenwalther.com/archive/2008/08/07/asp-net-mvc-tip-30-create-custom-route-constraints.aspx

Basically, I add a custom constraint on the route.

 routes.MapRoute("Content", "{*contentPath}", 
        new { controller = "Content", action = "RenderPageByURL" }, 
        new { matchController = new ContentRouteConstraint() });

 routes.MapRoute("Default","{controller}/{action}/{id}",
        new { id = UrlParameter.Optional });

ContentRouteConstraint() implements IRouteConstraint, and returns true on the Match method only if it doesn't match one of our existing route controllers. If the Match method fails on ContentRouteConstraint(), then it drops down to the next route.

The nice thing about this is I can ignore this route when trying to generate URLs (which we want to do in this instance).

Answer 2

Define the Content route below the Default in Globasl.asax.cs.

routes.MapRoute("Default","{controller}/{action}/{id}",
            new { id = UrlParameter.Optional });

routes.MapRoute("Content", "Content/{*contentPath}", 
            new { controller = "Content", action = "RenderPageByURL" });