the request is invalid? - asp.net

Question

Bit of a asp.net mvc noob , I am trying to pass in a string as an argument for my Web API controller:
public class ValuesController : ApiController
{
// GET api/values
public IEnumerable<string> Get()
{
return new string[] { "value1", "value2" };
}
// GET api/values/5
public string Get(int id)
{
return "value";
}
public string Get(string arg)
{
return "othervalue";
}
}
I tried to add another route:
routes.MapRoute(
name: "Default2",
url: "{controller}/{action}/{arg}",
defaults: new { controller = "Home", action = "Index", arg = UrlParameter.Optional }
);
So I want to keep both Get methods and use the Get with the arg parameter so I can pass in a string. So when I try to hit this url 'api/values/jjhjh' in my browser I get this error:
The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.String Get(Int32)' in 'stackOverflowWebApi.Controllers.ValuesController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.

Answer 1

The additional route you added was an MVC route, not a WebAPI route. WebAPI routes are not located in RouteConfig.cs by default, they are in WebApiConfig.cs. They look more like this:
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
The error you posted comes from not passing in any data at all. Give this a try instead:
public string Get(string id = null)
{
return "othervalue";
}
Note that the parameter name is id, not arg, to make it match the optional route parameter. Also, defaulting it to null tells the binder that its okay to invoke this method when no data is passed.