WebApi returns Http error 500, probably a routing issue

Question

I have the following Web Api class:

public class BizAuthController : ApiController
{
    [HttpPost]
    public __BizAuthModel Register([FromBody] __BizAuthModel authInfo)
    {
        if (ModelState.IsValid)
        {
          //... do whatever
        }
        throw new HttpResponseException(HttpStatusCode.BadRequest);
    }

    [HttpPost]
    public __BizAuthModel Login([FromBody] __BizAuthModel authInfo)
    {
        if (ModelState.IsValid)
        {
          //... do whatever
        }
        throw new HttpResponseException(HttpStatusCode.Forbidden);
    }

}

This is my WebApiConfig (standard, I didn't touch it):

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

        // Web API routes
        config.MapHttpAttributeRoutes();

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

Now, if I delete the "Login" method the "Register" can be called and works fine. If I keep the "Login" method then calling the "Register" returns Http Error 500. Why? and how can I fix this?

Answer 1

framework does not know which action to use on POST. Those two action match the default routeTemplate.

Update the convention-based route to api/{controller}/{action}/{id} and call the actions by name rather than by only HttpMethod. ie: POST api/BizAuth/Register and POST api/BizAuth/Login

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

        // Web API routes
        config.MapHttpAttributeRoutes();

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

    }
}