C# HttpClient Post using Json Object is failing

Question

Problem Statement:

I'm trying to post the data to the test url in C# using JSON data is failing, but when i try the same thing in Postman it succeeds.

C# Code snippet

            string uploadPath = @"https://api.test.com/test";
            string jsonData = "{ \"message\":\"ERROR: ABCDEXY: Price\"," +
            "\"source\":\"BYODB\"," +
            "\"tag\":[\"ABXT\",\"I232-F103\"],\"ID\":\"{76573406E8}\"}";

            using (var client = new HttpClient())
            {
                client.DefaultRequestHeaders.Add("Authorization", "apiKey " + "7cbafstad-677654c4-8765fgt-95deb");
                var content= new StringContent(jsonData, Encoding.UTF8, "application/json");
                content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
                HttpResponseMessage response = client.PostAsync(uploadPath, content).Result;
                var responseBody = response.Content.ReadAsStringAsync().Result;
                if (response.IsSuccessStatusCode)
                {
                    var sucessRes = JsonConvert.DeserializeObject<dynamic>(responseBody);
                    //Print Success Msg
                }
                else
                {
                    var failureRes = JsonConvert.DeserializeObject<dynamic>(responseBody);
                    //Print Failure Msg
                }
            }

Exception Details:

For Response Object, i'm receiving:

response = {StatusCode: 400, ReasonPhrase: 'Bad Request', Version: 1.1, Content: System.Net.Http.StreamContent, Headers:
{
  Transfer-Encoding: chunked
  Connection: keep-alive
  X-Response-Time: 0.001
  X-Request-ID: 4514d1b-1a3f-4277-9997-2813cd9d28ed
 X-Rat...

For Response Body, i'm receiving:

{"message":"Invalid JSON","took":0.001,"requestId":"4514d1b-1a3f-4277-9997-2813cd9d28ed"}

When i try to invoke this through postman,it is succeeding:

What i'm doing wrong in my C# JSON Post..?

Answer 1

The best approach is to use an actual object and let NewtonsoftJson take care of the serialization.

You will need two nuget packages for this:

1. Microsoft.AspNet.WebApi.Client
2. Newtonsoft.Json

The code looks like this:

using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

namespace Custom.ApiClient
{
    internal static class WebApiManager
    {
        //private const string _requestHeaderBearer = "Bearer";
        private const string _responseFormat = "application/json";

        private static readonly HttpClient _client;

        static WebApiManager()
        {

            // Setup the client.
            _client = new HttpClient { BaseAddress = new Uri("api url goes here"), Timeout = new TimeSpan(0, 0, 0, 0, -1) };

            _client.DefaultRequestHeaders.Accept.Clear();
            _client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(_responseFormat));

            // Add the API Bearer token identifier for this application.
            //_client.DefaultRequestHeaders.Add(RequestHeaderBearer, ConfigHelper.ApiBearerToken);       
        }
        public static async Task<T> Post<T>(object requestObject)
        {//the request object is the object being sent as instance of a class
            var response = _client.PostAsJsonAsync("api extra path and query params go here", requestObject);

            return await ProcessResponse<T>(response);
        }
        private static async Task<T> ProcessResponse<T>(Task<HttpResponseMessage> responseTask)
        {//T represents the respose you expect from this call
            var httpResponse = await responseTask;

            if(!httpResponse.IsSuccessStatusCode)
                throw new HttpRequestException(httpResponse.ToString());

            var dataResult = await httpResponse.Content.ReadAsAsync<T>();

            return dataResult;
        }
    }
}

To use this code you need to do something like this:

var myObject = new Object_I_Want_To_Send();
//set some properties here

var response = await WebApiManager.Post<MyResponse>(myObject);