Attribute routing and inheritance

Got it.

[Route("api/baseuploader/{action}")]
public abstract class BaseUploaderController : ApiController
{
    [HttpGet] 
    public string UploadFile() 
    {
        return "UploadFile";
    }
}


[Route("api/values/{action}")]
public class ValuesController : BaseUploaderController
{
    [HttpGet]
    public string Get(int id)
    {
        return "value";
    }
}

One caveat here is that the route action paramter must be the same as the action name. I could not find a way to get around that. (You cannot rename the route with a RouteAttribute)

Using Web API 2.2, you can:

public class BaseController : ApiController
{
    [Route("{id:int}")]
    public string Get(int id)
    {
        return "Success:" + id;
    }
}
[RoutePrefix("api/values")]
public class ValuesController : BaseController
{
}

config.MapHttpAttributeRoutes(new CustomDirectRouteProvider());
public class CustomDirectRouteProvider : DefaultDirectRouteProvider
{
    protected override IReadOnlyList<IDirectRouteFactory> 
    GetActionRouteFactories(HttpActionDescriptor actionDescriptor)
    {
        return actionDescriptor.GetCustomAttributes<IDirectRouteFactory>
        (inherit: true);
    }
}

as outlined here: http://www.asp.net/web-api/overview/releases/whats-new-in-aspnet-web-api-22

Attribute routes cannot be inherited. This was a deliberate design decision. We didn't feel right and didn't see valid scenarios where it would make sense to inherit them.

Could you give a more realistic scenario as to where you would want to use this?

[Update(3/24/2014)]
In the upcoming 5.2 release of MVC Web API, there is going to be an extensibility point called System.Web.Http.Routing.IDirectRouteProvider through which you can enable the inheritance scenario that you are looking for here. You could try this yourself using the latest night builds(documentation on how to use night builds is here)

[Update(7/31/2014)]
Example of how this can be done in Web API 2.2 release:

config.MapHttpAttributeRoutes(new CustomDirectRouteProvider());

//---------

public class CustomDirectRouteProvider : DefaultDirectRouteProvider
{
    protected override IReadOnlyList<IDirectRouteFactory> 
    GetActionRouteFactories(HttpActionDescriptor actionDescriptor)
    {
        // inherit route attributes decorated on base class controller's actions
        return actionDescriptor.GetCustomAttributes<IDirectRouteFactory>
        (inherit: true);
    }
}