Moving from RestSharp to HttpClient

Currently we are using RestClient from RestSharp library like below.

var client = new RestClient("<some url>");
var request = new RestRequest("", "GET");
request.AddHeader("content-type", RestClientModel.ContentType);
request.AddParameter("redirect_uri", RedirectUrl);
RestResponse response = await client.ExecuteAsync(request);
return response;

We are facing performance issues while using RestClient. That's the reason we want to move to HttpClient. So, we need help on the following points.

1. Using HttpClient instance in RestClient constructor which will be injected in respective class which will configure in startup.cs.
2. What is alternate for AddParameter in HttpClient? As this doesn't seems to be equivalent to adding headers in HttpClient.

Any help on this appreciated.

For GET request AddParameter adds query string parameter. Quote from docs:

var client = new RestClient("https://search.me");
var request = new RestRequest("search")
    .AddParameter("foo", "bar");
var response = await client.GetAsync<SearchResponse>(request);

> It will send a GET request to https://search.me/search?foo=bar".

You can try something like:

Dictionary<string, string> queryParams = new()
{
    { "redirect_uri", RedirectUrl }
};
var query= await new FormUrlEncodedContent(queryParams).ReadAsStringAsync();

var response = await client.GetAsync($"{someUrl}?{query}")

If you inject an HttpClient to the RestClient then your second question is pointless.

You can use the exact same code to add a parameter. You don't need to port that.

var httpClient = new HttpClient() { BaseAddress = new Uri("https://httpstat.us/") };
var client = new RestClient(httpClient);
var request = new RestRequest("200", Method.Get);
request.AddParameter("delay", "1000");

Console.WriteLine(client.BuildUri(request).AbsoluteUri);	

This will print: https://httpstat.us/200?delay=1000

Dotnet Fiddle link