Attribute routing - Enum not parsed

Question

I'm trying to make a route, but it's not working in this case:

If I call:

http://mysite.com/api/v1/product/Generic/1A 

works fine.

If I call:

http://mysite.com/api/v1/product?=Generic 

works too, but when I call:

http://mysite.com/api/v1/product/Generic 

I get this error:

{
 "Message":"The request is invalid.",
 "MessageDetail":"The parameters dictionary contains a null entry for parameter 'type'
 of non-nullable type 'GType' for method 'System.Net.Http.HttpResponseMessage 
 Get(GType)' in 'MySite.ControllersApi.V2.ProductController'. An optional parameter must 
 be a reference type, a nullable type, or be declared as an optional parameter."
}

The code of my route:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.Routes.MapHttpRoute
        (
            name: "DefaultApi",
            routeTemplate: "api/{version}/{controller}/{type}/{id}",
            defaults: new { id = RouteParameter.Optional, version = "v1", controller = "Product" }
        )
    }
}

public enum GType
{
    Big,
    Small,
    Generic,
}

And the Controller:

public HttpResponseMessage Get(GType type)
{
    ...
}

public HttpResponseMessage Get(GType type, string id)
{
    ...
}

So, Web API isn't parsing the value in the URL. Did I forget anything?

Answer 1

Well, I still can't see how your first url actually works, but the issue with the second url is that you are trying to pass an invalid bit of data as a parameter.

To keep it simple, I'm just going to pretend for a minute that your route definition is this:

 routeTemplate: "api/{controller}/{type}/{id}",
 defaults: new { id = RouteParameter.Optional }

If you were to call a GET on this url http://mysite.com/product/Generic , then you will get the same error you are running into. This url will resolve a controller of ProductController , with a parameter called type that will have a value of Generic .

However, your type parameter has an actual Type of GType , which is an enum. Generic is not a valid value for that so an error occurs. It's the same as sending "abcd" as the value for a parameter that is an int .

If you tried to call a get to http://mysite.com/product/Big , it would work, as it would be able to parse that value (Big) and a member of the GType enum.

Answer 2

The problem was that I have two equals routes, but with diferents parameters name.

api/{version}/{controller}/{type}/{id} 

and

api/{version}/{controller}/{id}

The second must be the last route declared.

Answer 3

The route you show us doesn't remotely match the URLs you're trying to hit. I have a feeling you're looking at the wrong route. Also, shouldn't "/Product/" be " /{controller}/" ?

Oh, and you mis-spelled routeTamplate [sic] in the snippet. I assume that was a transcription error -- I'm pretty sure the compiler would bark on that.