How to make an HTTP POST web request

Question

Canonical
How can I make an HTTP request and send some data using the POST method?

Answer 1

This is a complete working example of sending/receiving data in JSON format, I used Visual Studio 2013 Express Edition:

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.OleDb;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using System.Web.Script.Serialization;

namespace ConsoleApplication1
{
    class Customer
    {
        public string Name { get; set; }
        public string Address { get; set; }
        public string Phone { get; set; }
    }

    public class Program
    {
        private static readonly HttpClient _Client = new HttpClient();
        private static JavaScriptSerializer _Serializer = new JavaScriptSerializer();

        static void Main(string[] args)
        {
            Run().Wait();
        }

        static async Task Run()
        {
            string url = "http://www.example.com/api/Customer";
            Customer cust = new Customer() { Name = "Example Customer", Address = "Some example address", Phone = "Some phone number" };
            var json = _Serializer.Serialize(cust);
            var response = await Request(HttpMethod.Post, url, json, new Dictionary());
            string responseText = await response.Content.ReadAsStringAsync();

            List serializedResult = _Serializer.Deserialize>(responseText);

            Console.WriteLine(responseText);
            Console.ReadLine();
        }

        /// 

        /// Makes an async HTTP Request
        /// 
        /// Those methods you know: GET, POST, HEAD, etc...
        /// Very predictable...
        /// String data to POST on the server
        /// If you use some kind of Authorization you should use this
        /// 
        static async Task Request(HttpMethod pMethod, string pUrl, string pJsonContent, Dictionary pHeaders)
        {
            var httpRequestMessage = new HttpRequestMessage();
            httpRequestMessage.Method = pMethod;
            httpRequestMessage.RequestUri = new Uri(pUrl);
            foreach (var head in pHeaders)
            {
                httpRequestMessage.Headers.Add(head.Key, head.Value);
            }
            switch (pMethod.Method)
            {
                case "POST":
                    HttpContent httpContent = new StringContent(pJsonContent, Encoding.UTF8, "application/json");
                    httpRequestMessage.Content = httpContent;
                    break;

            }

            return await _Client.SendAsync(httpRequestMessage);
        }
    }
}