Warren recently reported this issue on Umbraco which prohibits WebApi from routing to two different paths that specify the same controller name but different namespaces. This type of thing is fully supported in MVC but not in WebApi for some reason.

Here’s a quick example, suppose we have two controllers:

namespace Test1
{
    [PluginController("Test1")]
    [IsBackOffice]
    public class ConfigController : UmbracoApiController
    {
        public int GetStuff()
        {
            return 9876;
        }
    }
}

namespace Test2
{
    [PluginController("Test2")]
    [IsBackOffice]    
    public class ConfigController : UmbracoApiController
    {
        public int GetStuff()
        {
            return 1234;
        }
    }
}

These controller definitions will create routes to the following paths respectively:

• /umbraco/backoffice/test1/config/getstuff
• /umbraco/backoffice/test2/config/getstuff

When these routes are created, the “Namespaces” data token is specified on the route, just like what is done in MVC, however in WebApi that needs to be done manually. Example:

var r = routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{id}",
    defaults: new { id = RouteParameter.Optional }
);
r.DataTokens["Namespaces"] = new string[] {"Foo"};

but if you navigate to either of these paths you’ll end up with a message like:

Multiple types were found that match the controller named 'Config'. This can happen if the route that services this request ('umbraco/backoffice/Test2/Config/{action}/{id}') found multiple controllers defined with the same name but differing namespaces, which is not supported. The request for 'Config' has found the following matching controllers: Test1.ConfigController Test2.ConfigController

Custom IHttpControllerSelector

To achieve what we want, we need to create a custom IHttpControllerSelector. I’ve created this in the Umbraco core to solve the issue and the source can be found HERE. The implementation is pretty straight forward – it relies on the default WebApi controller selector for everything unless a “Namespaces” data token is detected in the route and more than one controller type was found for the current controller name in the app domain.

There’s some posts out there that elude to the possibility of this being supported in WebApi in the future but as of the latest source code for the DefaultHttpControllerSelector, it appears that the functionality is not yet there.

If you need this functionality though, this implementation is working and pretty simple. To register this selector just use this code on startup:

GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpControllerSelector),
    new NamespaceHttpControllerSelector(GlobalConfiguration.Configuration));