How do I get the value of a custom RouteTemplate attribute in ASP.NET Web API 2?

Question

I wanted to create a custom route configuration that looks something like this:

config.Routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{location}/{id}",
    defaults: new { id = RouteParameter.Optional }

I need to have a location attribute which will contain an integer id denoting the location of a specific API user.

After that, I will be putting a custom attribute at the controller level, something like:

[VerifyLocation]
public class SomeController : ApiController

which does some background validation for the location value passed to every endpoint. This means I need to be able to get the integer value of the location attribute.

I am aware that you could use the Route attribute to customize your routes, but the thing is want to do this without having to put in a [Route("api/{location:id}/{id:int"}] on all my end points.

How do I go about doing this?

Answer 1

(In case someone stumbles upon this question)

One approach is through an ActionFilterAttribute:

public class VerifyLocation : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        var routeData = actionContext.RequestContext.RouteData;

        var location = routeData.Values["location"];

        // Do your thing here

        base.OnActionExecuting(actionContext);
    }
}