OWIN - Mapping Attribute Routes (Web API 2)

So last night I was playing around with OWIN and a small self-hosted application that made use of WebAPI 2. Everything was working fine until I tried to make use of the [RoutePrefix("")] and [Route("")] decorators on my controller (they just were not mapping). After a bit of digging I found out that you need to call config.MapHttpAttributeRoutes() in your OWIN Startup class and that should fix the mapping issue.

My initial attempt at this failed, and after a bit of playing around I figured out that the order in which you place the MapHttpAttributeRoutes and MapHttpRoute makes all the difference.

If you are wanting to make use of attribute routing in your OWIN application, this seems to be the winning order:

config.MapHttpAttributeRoutes();

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

Hopefully this helps you :)