WASM: HttpClient issue

[jkuehner75]

I created a UNO app with the templates using Basic Http.
The GetAsync line will fail and throw a silent exception so the navigation is not called. It also prevents breakpoints to be triggered.
Is there an issue with HttpClient? What do I need to consider? I do not need Kiota or so.
FYI WinUI works.

Jens

private async Task GoToSecondView()
{
    using var httpClient = new HttpClient();
    var response = await httpClient.GetAsync("https://platform.uno/");
    //response.EnsureSuccessStatusCode();

    await _navigator.NavigateViewModelAsync<SecondViewModel>(this, data: new Entity(Name!));
}

[jkuehner75]

Log:
fail: Uno.UI.Dispatching.NativeDispatcher[0]
NativeDispatcher unhandled exception
System.Net.Http.HttpRequestException: TypeError: Failed to fetch
---> TypeError: Failed to fetch
--- End of inner exception stack trace ---
at System.Net.Http.BrowserHttpInterop.CancellationHelper(Task promise, CancellationToken cancellationToken, JSObject jsController)
at System.Net.Http.BrowserHttpController.CallFetch()
at System.Net.Http.HttpClient.g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)
at UnoHttp.Presentation.MainViewModel.GoToSecondView() in C:\Users\jkueh\source\repos\UnoHttp\UnoHttp\Presentation\MainViewModel.cs:line 43
at CommunityToolkit.Mvvm.Input.AsyncRelayCommand.AwaitAndThrowIfFailed(Task executionTask)
at System.Threading.Tasks.Task.<>c.b__128_0(Object state)
at Uno.UI.Dispatching.NativeDispatcherSynchronizationContext.<>c__DisplayClass3_0.b__0() in C:\a\1\s\src\Uno.UI.Dispatching\Native\NativeDispatcherSynchronizationContext.cs:line 21
at Uno.UI.Dispatching.NativeDispatcher.RunAction(NativeDispatcher dispatcher, Action action) in C:\a\1\s\src\Uno.UI.Dispatching\Native\NativeDispatcher.cs:line 153

[MartinZikmund]

@jkuehner75 this is most likely a CORS issue - the target URI has to have permissive CORS to allow you to send requests - it is a general security limitation of web browser sandbox. This is different from native applications where this limitation does not exist. If you are in control of the API, you can set up CORS so that your Uno Platform app can communicate with it.

[jkuehner75]

Yes I own the Api and although I set this it does not work:

        //App
        var app = builder.Build();

        // Configure the HTTP request pipeline.
        if (app.Environment.IsDevelopment())
        {
            app.MapOpenApi();
        }

        app.UseHttpsRedirection();
        app.UseRouting();

          app.UseCors(builder => builder
          .AllowAnyOrigin()
          .AllowAnyMethod()
          .AllowAnyHeader()
          );

        app.UseAuthentication(); //new
        app.UseAuthorization();

        app.MapControllers();

        app.MapHub<BuildeHub>("/BuilderHub");

        app.Run();

[MartinZikmund]

If you go into the network tab in Developer Tools in your browser, do you see some info about the failed HTTP request?

[jkuehner75]

Next day it worked with the Cors. Maybe cache not updated. It works.

[MartinZikmund]

That's great news!