How to prevent controllers in wrong areas from being used in MVC5

Question

My MVC application is set up with controllers at the root/global level. These have no explicit Area. I also have a single "Admin" area. URLs that begin with /admin/ are routed to the matching controller in the Admin area. Other URLs are routed to the matching global controller. This is working fine for the most part.

The issue I'm having is that in the case when a URL matches a controller in the Admin area when one of the same name doesn't exist on the global area, the request is incorrectly routed to the controller in Admin area. I know this is happening because I put a breakpoint on the matching action in the relevant controller.

For example, I have a controller called CalendarController in the Admin area. When I visit /admin/calendar, it works because it finds the action and the corresponding view in Areas/Admin/Views/Calendar/Index.cshtml. The problem occurs when I visit /calendar. I do not have a controller named Calendar at the root level, but for some reason it routes the request to the Admin area's CalendarController, which I don't want. I want it to return a 404 because no CalendarController exists at the root level. Instead, I get an error because it's searching for the view at the root level (at /Views/Calendar/Index.cshtml) even though the matching controller was in the Admin area.

How can I prevent the Admin area from being searched for matching controllers except when the URL has /admin in it?

Here's the relevant route code, which is basically stock except for the namespaces addition. The issue still happens without the namespace. There are more routes in the actual application, but I'm getting the same behavior in a brand new MVC project.

public class AdminAreaRegistration : AreaRegistration 
{
    public override string AreaName 
    {
        get 
        {
            return "Admin";
        }
    }

    public override void RegisterArea(AreaRegistrationContext context) 
    {
        context.MapRoute(
            "Admin_default",
            "Admin/{controller}/{action}/{id}",
            new { action = "Index", id = UrlParameter.Optional },
            new[] { "AreaProblem.Areas.Admin.Controllers" }
        );
    }
}

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

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

What I mean by a controller at the "root level" is Controllers/HomeController in this screenshot. I want URLs that don't start with /admin to only look at those controllers. The problem is that it's also searching in Areas/Admin/Controllers.

Answer 1

So the MVC routing engine will look in different namespaces to try and find a matching controller. You can solve this by specifying a namespace (like you did for the admin area). You can also specify that a route not search other namespaces using DataTokens.

routes.MapRoute(
    "Default",
    "{controller}/{action}/{id}",
    new { controller = "Home", action = "Index", id = UrlParameter.Optional },
    namespaces: new [] { "AreaProblem.Controllers" }
    ).DataTokens["UseNamespaceFallback"] = false;