Json method is not recognized in Web Api controller

Question

I have an web api controller

using sport.BLL.Abstract;
using sport.BLL.Concrete;
using sport.DAL.Entities;
using sport.webApi.Models;
using AutoMapper;
using Microsoft.AspNet.Identity.EntityFramework;
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNet.Identity;
using Microsoft.AspNet.Identity.Owin;  
using Microsoft.Owin.Security;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using System.Web;
using System.Web.WebPages.Html;

namespace sport.webApi.Controllers 
{
    public class AccountManageController : ApiController
    {
        [HttpPost]
        public System.Web.Mvc.ActionResult CreateAccount(CollaborateurModel item)
        {
            var user = new ApplicationUser { UserName = item.Username, Email = item.Email };
            var result = UserManager.CreateAsync(user, item.Password);
            if (result.Result.Succeeded)
            {

                var currentUser = UserManager.FindByName(item.Username);
                var roleresult = UserManager.AddToRole(currentUser.Id, item.Role);
                ajt_collaborator entity = Mapper.Map<CollaborateurModel, ajt_collaborator>(item);
                entity.id_user_fk = currentUser.Id;
                entity.is_deleted = false; 
                repo.CreateCollaborator(entity); 
                var response = new { Success = true }; 
                return  Json(response);


            }
            else
            {
                var errorResponse = new { Success = false, ErrorMessage = "error" };
                return  Json(errorResponse);
            }

        }
    }
}

I got an error in this line :

return Json(response);

the Json Method is not recognized!!! when I googled about that I get this link which indicates that Json method is included in System.Web.Mvc. Even I try to import this namespace I get the same error?

1. So is the reason of this error?
2. How can I fix it?

Answer 1

The problem is that you are inheriting from ApiController but Json is a member of System.Web.Mvc.Controller.

Try using JsonResult:

return new JsonResult { data = yourData; }

You can set any object to a data as it will be serialized to a JSON.

For instance, if you need to return only a result of operation, you can use it this way:

return new JsonResult { data = true; } // or false

However, it is a good practice to describe a result class and return objects.

Answer 2

How can I fix it?

The reason is in the fact that you aren't inheriting from Controller but from ApiController, where the former has Json(object o) as a method in it's base class, but that doesn't actually matter, as there is a fundamental problem with your approach.

ApiController which is used with WebAPI isn't meant to return an ActionResult, which is a concept that belongs to MVC. Instead, you simply return your POCO and let the WebAPI framework handle serialization for you:

public object CreateAccount(CollaborateurModel item)
{
    // Do stuff:
    if (result.Result.Succeeded)
    {
        return new { Success = true }
    }
    else
    {
        return new { Success = false, ErrorMessage = "error" };   
    }                               
}

You can set your formatter configuration in your Global.asax.cs file, and tell it exactly which ones to use (in your case, you'll want the JsonMediaTypeFormatter).