Web API route not getting called

Question

This is my web API config:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        // Web API configuration and services

        // Web API routes
        config.MapHttpAttributeRoutes();

        config.Routes.MapHttpRoute(
           name: "ReaderTags",
           routeTemplate: "Reader/{readerID}/Tags"
       );

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

    }
}

I want that when I call my URL /Reader/abc/Tags it should call my ReaderController's Tags action and pass abc as the string parameter.

But somehow it is using the DefaultAPI's route and trying to find abc as an action in ReaderController.

What am I missing?

Answer 1

The route mapping is missing defaults that would let the route table know what controller and action to invoke for routes matching the template

config.Routes.MapHttpRoute(
    name: "ReaderTags",
    routeTemplate: "Reader/{readerID}/Tags",
    defaults: new { controller = "Reader", action = "Tags" }
);

The route template also assumes that the string parameter on the action shares the same name: i.e: readerID.

public IHttpActionResult Tags(string readerID) {
    //...
}

And since config.MapHttpAttributeRoutes(); is also configured, then the same can be achieved via attribute routing instead of convention-based routing like this

//GET Reader/abc/Tags
[HttpGet]
[Route("Reader/{readerID}/Tags")]
public IHttpActionResult Tags(string readerID) {
    //...
}