C#•2y ago

❔ ✅ Why doesn't this basic HttpClient GET request doesn't work as expected?

I do not get anything past making a request. Neither an exception, nor an exception. I'm guessing it's because I'm not properly waiting for async to complete - but in that case what is it lacking? Program.cs

HttpClientLib httpClientLib = new();
httpClientLib.RequestGet();

HttpClientLib httpClientLib = new();
httpClientLib.RequestGet();

HttpClientLib.cs

using System.Net.Http;

public class HttpClientLib
{
    public async void RequestGet()
    {
        try
        {
            using (var client = new HttpClient()) {
                var url = "https://dummy.restapiexample.com/api/v1/employees";
                HttpResponseMessage response = await client.GetAsync(url);
                Console.WriteLine(response.StatusCode);
                response.EnsureSuccessStatusCode();
                string responseBody = await response.Content.ReadAsStringAsync();
                Console.WriteLine(responseBody);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Generic exception caught: {ex.Message}");
        }
    }
}

using System.Net.Http;

public class HttpClientLib
{
    public async void RequestGet()
    {
        try
        {
            using (var client = new HttpClient()) {
                var url = "https://dummy.restapiexample.com/api/v1/employees";
                HttpResponseMessage response = await client.GetAsync(url);
                Console.WriteLine(response.StatusCode);
                response.EnsureSuccessStatusCode();
                string responseBody = await response.Content.ReadAsStringAsync();
                Console.WriteLine(responseBody);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Generic exception caught: {ex.Message}");
        }
    }
}

14 Replies

Pobiega•2y ago

async void change that to be async Task and await it at the top level also, don't using var client like that, its bad practice

FusedQyou•2y ago

Why? Does it not log the exception? It should do that

fooo1OP•2y ago

ahh I see. I wrongly assumed void and Task are both valid types, depending on your needs, but seems async code should always (for beginners atleast) be Task - is that correct? As per your suggestion, changed using to be declerative - using HttpClient client = new();

Pobiega•2y ago

no you shouldnt be using a httpclient

FusedQyou•2y ago

It should always return a Task so it can be properly awaited. There are very strict edge cases where you don't need to do that, but you probably won't encounter them. By making it a Task, you can properly await any errors.

Pobiega•2y ago

https://learn.microsoft.com/en-us/dotnet/fundamentals/networking/http/httpclient-guidelines

// HttpClient is intended to be instantiated once per application, rather than per-use. See Remarks.
static readonly HttpClient client = new HttpClient();

static async Task Main()
{
    // Call asynchronous network methods in a try/catch block to handle exceptions.
    try
    {
        using HttpResponseMessage response = await client.GetAsync("http://www.contoso.com/");
        response.EnsureSuccessStatusCode();
        string responseBody = await response.Content.ReadAsStringAsync();
        // Above three lines can be replaced with new helper method below
        // string responseBody = await client.GetStringAsync(uri);

        Console.WriteLine(responseBody);
    }
    catch (HttpRequestException e)
    {
        Console.WriteLine("\nException Caught!");
        Console.WriteLine("Message :{0} ", e.Message);
    }
}

// HttpClient is intended to be instantiated once per application, rather than per-use. See Remarks.
static readonly HttpClient client = new HttpClient();

static async Task Main()
{
    // Call asynchronous network methods in a try/catch block to handle exceptions.
    try
    {
        using HttpResponseMessage response = await client.GetAsync("http://www.contoso.com/");
        response.EnsureSuccessStatusCode();
        string responseBody = await response.Content.ReadAsStringAsync();
        // Above three lines can be replaced with new helper method below
        // string responseBody = await client.GetStringAsync(uri);

        Console.WriteLine(responseBody);
    }
    catch (HttpRequestException e)
    {
        Console.WriteLine("\nException Caught!");
        Console.WriteLine("Message :{0} ", e.Message);
    }
}

read that top comment you should NOT be creating/disposing HttpClients willy-nilly https://learn.microsoft.com/en-us/dotnet/api/system.net.http.httpclient?view=net-8.0 yeah, always use Task. async void is for fire and forget event handlers, which this is not. unawaited async operation, so the application probably exits before the http requets is made

FusedQyou•2y ago

Dunno, not enough context

Pobiega•2y ago

sure, but thats the most likely answer for it not printing/throwing an exception not to mention that async void swallows all exceptions anyways 😛

fooo1OP•2y ago

Thank you for the help. Reading through the docs again to understand better

Pobiega•2y ago

👍 $close

MODiX•2y ago

Use the /close command to mark a forum thread as answered

Pobiega•2y ago

if thats what you were going for 🙂

fooo1OP•2y ago

yeapp, will know now

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ ✅ Why doesn't this basic HttpClient GET request doesn't work as expected?