MVC не может получить JSON из запроса Post "x-form-urlencoded"

Question

Я пытаюсь получить JSON из тела, но всегда получаю ноль.

Это мой код в MVC

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Script.Serialization;
using System.Web.Mvc;
using System.Web.Http;
using System.Net.Http;
using System.Net;
using System.IO;

namespace WebApplication5.Controllers
{
    public class NimsoftController : Controller
    {
        static readonly Dictionary<Guid, Alert> alerts = new Dictionary<Guid, Alert>();

        // GET: Nimsoft
        //public ActionResult CreateAlarm()
        [System.Web.Mvc.HttpPost]
        public HttpResponseMessage CreateAlarm([FromBody] Alert val)
        {
            Models.CreateAlarm CreateAlarm = new Models.CreateAlarm();
            System.IO.File.AppendAllText(@"D:\log.txt", string.Join(",", val.message));
            string jsonAlarm = new JavaScriptSerializer().Serialize(new
            {
               message = "Test Message"//string.Join(",",alert.alerts),
            });

            var response = new HttpResponseMessage(HttpStatusCode.Created)
            {
                Content = new StringContent(jsonAlarm)
            };

            return response;
        }
    }
}

и мой запрос

User-Agent: Fiddler
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Content-type: application/x-www-form-urlencoded
Host: localhost:52151
Content-Length: 27 '

Answer 1

Вы должны установить для параметра mediaType для StringContent значение application/json:

Content = new StringContent(jsonAlarm, Encoding.UTF8, "application/json");