custom mapRoute for special controller and action to be like this in MVC: http://example.com/someValue

Question

I have this default mapRoute:

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

and some other mapRoutes for some other sontrollers before default,

now, I want a mapRoute for special controller to show the url like : myDomain.com/someValue, but when I use this:

routes.MapRoute(
name: "categories",
url: "{sub}",
defaults: new { controller = "cat", action = "Index" }
);

all of my url.Actions which have "Index" as action like @Url.Action("index","login") not work, I have also used :

sub=UrlParameter.Optional

and

sub=""

, but they did not work, what should I do ?

Answer 1

Your categories route catches all urls because it is match with the role. You need to write a custom constraint class to filter out unmatched subs form your database for example.

public class MyCatConstraint : IRouteConstraint
{
    // suppose this is your cats list. In the real world a DB provider 
    private string[] _myCats = new[] { "cat1", "cat2", "cat3" };

    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
    {
        // return true if you found a match on your cat's list otherwise false
        // in the real world you could query from DB to match cats instead of searching from the array.  
        if(values.ContainsKey(parameterName))
        {
            return _myCats.Any(c => c == values[parameterName].ToString());
        }
        return false;
    }
}

and then add this constraint to your route.

routes.MapRoute(
    name: "categories",
    url: "{sub}",
    defaults: new { controller = "cat", action = "Index" }
    ,constraints: new { sub = new MyCatConstraint() }
    );