API Frequency Limit Issue: Overriding SendAsync in HttpClient Inherited Class Fails

[zms9110750]

The API I need to access has a frequency limit. Therefore, I created a class that inherits from HttpClient and overridden the SendAsync method. However, I still encountered an "access too fast" error when making calls.

After checking the source code, I found that some methods call base.SendAsync. As a result, my override doesn't work. Is this by design?

[MihaZupan]

The SendAsync override there probably should have been sealed.

If you want to modify behavior of all calls, you can create a custom DelegatingHandler instead, then use it when creating the HttpClient (or configure the IHttpClientFactory to use it if you're using that).
E.g.

var httpClient = new HttpClient(new MyHandler(new SocketsHttpHandler()));

sealed class MyHandler(HttpMessageHandler inner) : DelegatingHandler(inner)
{
    protected async override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        await Task.Delay(5000, cancellationToken);
        return await base.SendAsync(request, cancellationToken);
    }
}