How to add parameters when using HttpClient to send request .Net Core C#?

Question

How to add parameters when using HttpClient to send request?

I have a problem with my target API; it takes two parameters, and I need to figure out how to add two parameters to my request. Would anyone please explain how I can make that call with HttpClient?

My target API's signature, which I am going to call, looks like:

//It takes post call only
public string Authentication(string UN, string AP)

This is in my startup.cs:

services.AddHttpClient("Authentication", APIHttpClient =>
{
    APIHttpClient.BaseAddress = new Uri("Target API address");
}).ConfigurePrimaryHttpMessageHandler(() =>
    new HttpClientHandler
    {
        UseCookies = false
    }
);

in my class:

public class MyService 
{
   private IHttpClientFactory _clientFactory;

   public MyService(IHttpClientFactory httpClientFactory){
       _clientFactory = httpClientFactory;
   }

   public MyMethod(){

       HttpClient httpClient 
       _httpClientFactory.CreateClient("Authentication");
       
       // I need to add parameter here
   }
}

Hopefully, someone can show me how to code it, Thank you!

Answer 1

You could send request with parameters like below if the api is POST request:

HttpClient httpClient = _clientFactory.CreateClient("Authentication");

// Create parameters
var parameters = new Dictionary<string, string>
{
    { "UN", "aa" },
    { "AP", "bbb" }
};

// Convert parameters to form-urlencoded content
var content = new FormUrlEncodedContent(parameters);

// Send POST request
var response = await httpClient.PostAsync("/auth", content);

The API:

[HttpPost]
[Route("/auth")]
public string Authentication([FromForm]string UN, [FromForm]string AP)
{
    return UN;
}

If the api is GET request:

HttpClient httpClient = _clientFactory.CreateClient("Authentication");

// Create query string with parameters
var queryString = new StringBuilder();
queryString.Append("?UN=").Append(Uri.EscapeDataString("aa"));
queryString.Append("&AP=").Append(Uri.EscapeDataString("bb"));

// Append query string to base URL
string requestUrl = "/auth" + queryString;

// Send GET request
var response = await httpClient.GetAsync(requestUrl);