Detailed explanation of the HTTP POST request method that contains body data in.NET

This article introduces several methods to send HTTP POST requests in .NET and pass body data.

1. HttpClient (recommended)

HttpClient is the preferred HTTP request method for .NET Core and later versions of .NET Framework. It provides asynchronous and high-performance operations.

using System.Net.Http;
var client = new HttpClient();
var values = new Dictionary
{
    { "thing1", "hello" },
    { "thing2", "world" }
};
var content = new FormUrlEncodedContent(values);
var response = await client.PostAsync("http://www.example.com/recepticle.aspx", content);

2. Third-party library

RestSharp:

using RestSharp;
var client = new RestClient("http://example.com");
var request = new RestRequest("resource/{id}");
request.AddParameter("thing1", "Hello");
request.AddParameter("thing2", "world");
var response = client.Post(request);

Flurl.Http:

using Flurl.Http;
var responseString = await "http://www.example.com/recepticle.aspx"
    .PostUrlEncodedAsync(new { thing1 = "hello", thing2 = "world" })
    .ReceiveString();

3. HttpWebRequest (not recommended for new projects)

POST:

using System.Net;
using System.Text;
var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");
var postData = "thing1="   Uri.EscapeDataString("hello");
postData  = "&thing2="   Uri.EscapeDataString("world");
var data = Encoding.ASCII.GetBytes(postData);
using (var stream = request.GetRequestStream()) { stream.Write(data, 0, data.Length); }
var response = request.GetResponse();

GET:

var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");
var response = request.GetResponse();

4. WebClient (not recommended for new projects)

POST:

using System.Net;
using System.Collections.Specialized;
using (var client = new WebClient())
{
    var values = new NameValueCollection();
    values["thing1"] = "hello";
    values["thing2"] = "world";
    var response = client.UploadValues("http://www.example.com/recepticle.aspx", values);
}

GET:

using (var client = new WebClient()) { var responseString = client.DownloadString("http://www.example.com/recepticle.aspx"); }

This article compares various methods of sending HTTP POST requests by .NET and recommends using HttpClient. For new projects, it is highly recommended to use HttpClient as it is more modern, performs better, and supports asynchronous operations.