ASP.NET Web API routing with action parameter

Question

in the WebApiConfig.cs file of my Web API project I have replaced the default routing mapping to this one:

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

as I want controller and action combinations instead of a lot of GETs and POSTs.

The problem is this. I have a controller CityController with below 2 actions.

[HttpGet]
        public HttpResponseMessage GenderCount()
        {
            //Validate session and fetch gender related data of the city
            return Request.CreateResponse(HttpStatusCode.OK, genderData);                
        }

        [HttpGet]
        public HttpResponseMessage GenderCount(string cityID)
        {
            //Validate session and fetch gender related data of the city
            return Request.CreateResponse(HttpStatusCode.OK, genderData);                
        }

The {HostName}/api/City/GenderCount?cityID=4 API call works but when I try to issue the same API call in the {HostName}/api/City/GenderCount/4 format, it goes to the without-parameter 'GenderCount()' action.

It is unable to map the id route parameter. change action parameter from string cityID to string id or do the reverse and update the route itself. — Nkosi
– Nkosi, Commented Nov 29, 2017 at 13:32
@Nkosi your answer worked partly. in the 'reverse' case, the POST actions could not be found with 404 resource not found message. Why did you not put this as the actual answer instead of Comment? — user1451111
– user1451111, Commented Nov 30, 2017 at 6:51

Nishith Shah · Accepted Answer · 2017-11-30 18:04:04Z

1

If you already have a route prefix

[RoutePrefix("api/City")]

on your controller, try decorating your method with attribute routing.

[Route("GenderCount/{cityID}"]

OR

use full route path

[Route("api/City/GenderCount/{cityID}")]

edited Nov 30, 2017 at 18:04

answered Nov 29, 2017 at 17:07

Nishith Shah

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4 Comments

user1451111 Over a year ago

The without parameter action method is invoked even after enabling attribute routing and decorating the action, as you advised.

user1451111 Over a year ago

I have also verified the namespace of the route attribute which is "System.Web.Http".

user1451111 Over a year ago

It is fixed now. I had to add [Route("api/City/GenderCount/{cityID}")] instead of only [Route("{cityID}")]. If you update your answer accordingly, I can accept it. Probably you assumed that my CityController already has [RoutePrefix("api/City")] linked with it.

Nishith Shah Over a year ago

@user1451111 Yes, I assumed that you have RoutePrefix. Edited my answer.

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