Post Action method overload with same route name in ASP.Net Web API Controller

Question

Is it possible to have two actions with same route name and same method but different parameter? I have tried this:

[HttpPost]
[Route("gstr4")]
public HttpResponseMessage SubmitGSTR4([FromBody] RequestPayloadWithoutSign requestPayload)
{ }

[HttpPost]
[Route("gstr4")]
public HttpResponseMessage FileGSTR4([FromBody] RequestPayloadWithSign requestPayload)
{ }

I received a Status Code of 500 (InternalServerError) and here is raw response:

{"Message":"An error has occurred.","ExceptionMessage":"Multiple actions were found that match the request: \r\nFileGSTR4 on type APIPortal.Controllers.GSTR4Controller\r\nSubmitGSTR4 on type APIPortal.Controllers.GSTR4Controller","ExceptionType":"System.InvalidOperationException","StackTrace":"   at System.Web.Http.Controllers.ApiControllerActionSelector.ActionSelectorCacheItem.SelectAction(HttpControllerContext controllerContext)\r\n   at System.Web.Http.Controllers.ApiControllerActionSelector.SelectAction(HttpControllerContext controllerContext)\r\n   at System.Web.Http.ApiController.ExecuteAsync(HttpControllerContext controllerContext, CancellationToken cancellationToken)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()"}

Answer 1

It's not possible for the same method type as http Get for multiple methods. You should have a different route

Answer 2

It is only possible with different HTTP verbs. Otherwise, you have to define different routes.

https://docs.microsoft.com/en-us/aspnet/web-api/overview/web-api-routing-and-actions/routing-in-aspnet-web-api

Answer 3

It's not possible to have many actions with the same route and the same HTTP verb.

What you could do is to have a single action which accepts a base class and a custom resolver.

For example:

public abstract class RequestPayload 
{
}

public class RequestPayloadWithoutSign : RequestPayload
{
}

public class RequestPayloadWithSign : RequestPayload
{
   public string Sign { get; set; }
}

And a custom JSON resolver attached to your JSON deserializer.