Passing Authentication Header Token when Posting Data to API Using C#

A guide on how to pass the Authentication Header Token when making a POST request to an API using C# by utilizing HttpClient and a Bearer Token.

In this article, you'll learn how to pass an Authentication Header Token when making a POST request to an API using C#. We will use the HttpClient class to send data along with a Bearer Token in the request header.

C# code:

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

class Program
{
    static async Task Main(string[] args)
    {
        // API URL
        var apiUrl = "https://example.com/api/data";

        // Your Token
        var token = "your_token_here";

        // POST data
        var jsonData = "{\"name\":\"John Doe\",\"age\":30}";
        
        using (var client = new HttpClient())
        {
            // Add Authentication Header with Bearer Token
            client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token);

            // Create HttpContent from JSON data
            var content = new StringContent(jsonData, Encoding.UTF8, "application/json");

            // Send POST request
            var response = await client.PostAsync(apiUrl, content);

            // Check the result
            if (response.IsSuccessStatusCode)
            {
                var responseData = await response.Content.ReadAsStringAsync();
                Console.WriteLine($"Response from API: {responseData}");
            }
            else
            {
                Console.WriteLine($"Request failed. Status Code: {response.StatusCode}");
            }
        }
    }
}

Detailed explanation:

1. using System.Net.Http: Includes the System.Net.Http namespace to work with HttpClient.
2. var apiUrl = "https://example.com/api/data";: The URL of the API you want to send data to.
3. var token = "your_token_here";: Assigns your token to the token variable.
4. client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token);: Passes the token into the Authentication Header as "Bearer".
5. var content = new StringContent(jsonData, Encoding.UTF8, "application/json");: Creates an HttpContent object from the JSON data to be sent with the request.
6. var response = await client.PostAsync(apiUrl, content);: Sends the POST request to the API with the JSON data and token in the header.
7. if (response.IsSuccessStatusCode): Checks if the request was successful and processes the response accordingly.

System Requirements:

• .NET Core 3.1 or higher, or .NET Framework 4.5 or higher.

How to install:

Use the following command to create a new .NET Core Console project:

dotnet new console -n MyHttpClientApp

Tips:

• Always validate the token before making the request.
• Use try-catch blocks to handle potential errors when sending HTTP requests.