MVC Routing - wildcard URL, but constrained

Question

I basically want to do this:

routes.MapRoute(
  "Pass-through",
  "/api/{*url}",
  new { controller = "PassThrough", action = "PassThroughToApi" });

and the controller I am directing the request to has:

public ContentResult PassThroughToApi(string url = null)

However, I want to be able at the same time to constraint the URL. Such as:

routes.MapRoute(
  "Pass-through",
  "/api/v1/some/specific/address/{whatever}/{parameters}",
  new { controller = "PassThrough", action = "PassThroughToApi" });

But I still want the Controller to get the requested URL as a variable and I don't care about getting the actual parameters, as long as the URL matches the pattern. Or should I just get the requested URL from another place, like a context, instead of being passed to it as a parameter?

Answer 1

You can create custom route constraint

public class ApiRedirectingConstraint : IRouteConstraint
{
    private string _matchUrl;

    public ApiRedirectingConstraint(string matchUrl)
    {
        _matchUrl = matchUrl;
    }

    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
    {
        string url = (string)values["url"];

        bool isMatch = true;
        //check url for specific match with _matchUrl

        return isMatch;
    }
}

and assign it to the Pass-through route

routes.MapRoute(
    "Pass-through",
    "/api/{*url}",
    new { controller = "PassThrough", action = "PassThroughToApi" },
    new { apiRedirect = new ApiRedirectingConstraint("/api/v1/some/specific/address/{whatever}/{parameters}") }
);