How to replace obsolete WebClient with HttpClient in .NET 6

Question

Since WebClient is deprecated in .NET 6, I want to convert the following code using WebClient with an equivalent code using HttpClient for calling a REST Web API:

using WebClient client = new();
client.Encoding = Encoding.UTF8;
client.Headers.Set(HttpRequestHeader.ContentType, "application/json");
client.Headers.Add("user_key", tokens[0]);
client.Headers.Add("Session_key", tokens[1]);
string json = JsonSerializer.Serialize(sms);
string serverResponse = client.UploadString(_baseUrl + "sms", "POST", json);

For now, I implemented the following solution:

HttpClient httpClient = _httpClientFactory.CreateClient();
HttpRequestMessage request = new(HttpMethod.Post, _baseUrl + "sms");
request.Headers.Add("user_key", tokens[0]);
request.Headers.Add("Session_key", tokens[1]);
string json = JsonSerializer.Serialize(sms);
request.Content = new StringContent(json, Encoding.UTF8, MediaTypeNames.Application.Json);
using HttpResponseMessage response = await httpClient.SendAsync(request);
response.EnsureSuccessStatusCode();

I think that the above solution is the cleanest and most efficient way to replace the original code. Can an EXPERT confirm this?

score 14 · Answer 1 · answered Dec 06 '21 at 22:41

.Net 6 supports synchronous Send()

Here's a simple GET:

using var httpClient = new HttpClient();
var request = new HttpRequestMessage(HttpMethod.Get, "https://api.example.com/api/v1/get");
var response = httpClient.Send(request);
using var reader = new StreamReader(response.Content.ReadAsStream());
var responseBody = reader.ReadToEnd();

Here's a POST:

var handler = new HttpClientHandler {
    AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate
};

var client = new HttpClient(handler) {
    BaseAddress = new Uri(_baseurl) 
};

var webRequest = new HttpRequestMessage(HttpMethod.Post, "sms") {
    Content = new StringContent(json, Encoding.UTF8, "application/json")
};

webRequest.Headers.Add("user_key", tokens[0]);
webRequest.Headers.Add("Session_key", tokens[1]);

var response = client.Send(webRequest);
var reader = new StreamReader(response.Content.ReadAsStream());
var responseBody = reader.ReadToEnd();

Your answer does not provide any valuable details about why it is better than the solution the OP is currently using. — Lemiarty, Feb 04 '22 at 00:21
It's not "bettter" - but it is a new feature that people may want to know exists. — Chris Harrington, Feb 12 '22 at 21:14

score 3 · Answer 2 · answered Dec 01 '21 at 15:07

Seems simple enough:

HttpClient client = new()
{
    BaseAddress = new Uri(_baseUrl)
};

using HttpRequestMessage request = new(HttpMethod.Post, "sms");
request.Headers.Add("user_key", tokens[0]);
request.Headers.Add("Session_key", tokens[1]);

string json = JsonSerializer.Serialize(sms);
request.Content = new StringContent(json, Encoding.UTF8)
{
    Headers =
    {
        ContentType = new("application/json")
    }
};

using HttpResponseMessage response = await client.SendAsync(request);
response.EnsureSuccessStatusCode();
string serverResponse = await response.Content.ReadAsStringAsync();

However, you'll probably want to use the IHttpClientFactory to create your HttpClient instances, since that provides several benefits - particularly pooling the underlying message handler, to avoid performance problems.

You might also want to consider using the PostAsJsonAsync extension method, which could simplify this code.

But there is no easy way to track download/upload progress compared to WebClient, right? You would need to do some stream writeasync/readasync logic. — AyCe, Feb 16 '22 at 08:23
@AyCe It doesn't look too bad: [Progress bar with HttpClient](https://stackoverflow.com/a/69826649/124386) — Richard Deeming, Feb 16 '22 at 10:02
Yes, that's what I mean, I saw that too. The question was for Windows Runtime, I haven't checked how compatible to .NET Framework/Core/5.0/6.0 this is yet. — AyCe, Feb 16 '22 at 10:07

How to replace obsolete WebClient with HttpClient in .NET 6

2 Answers2