Aspnetcore: Blazor HttpClientHandler.SendAsync is wiped

[joelhays]

Describe the bug

Blazor HttpClientHandler.SendAsync is wiped. Similar issue here https://github.com/aspnet/Blazor/issues/1484 that mentions a correction in 0.7.0 and working with the mono team to add support.
I am using Blazor 0.9.0-preview3-19154-02.

To Reproduce

Steps to reproduce the behavior:

1. Using this version of ASP.NET Core '3.0.100-preview3-010431'
2. Invoke the SendAsync method on the HttpClientHandler

Expected behavior

Expect the method to invoke a web request

Additional context

Unexpected error in HttpContent POST with result: Cannot invoke method because it was wiped. See stack trace for details.
System.NotImplementedException: Cannot invoke method because it was wiped. See stack trace for details.
components.webassembly.js:1 WASM:
at System.Net.Http.HttpClientHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)

[mkArtakMSFT]

Thanks for contacting us, @joelhays.
Can you please share a repro project so we can investigate this better?
/cc @SteveSandersonMS thoughts?

[joelhays]

@mkArtakMSFT, I'm working on creating a minimal example that I can share.

In the meantime, here's some additional information I found:

If I create a brand new HttpClient before every request, it works just fine. However, I have nested object structure that's creating the client and holding a reference to it for the entire lifecycle. When I try to submit a request with that reuseable HttpClient, that's when the issue occurs.

If it helps, I have a queue of requests and on an interval, I process the queue and submit all requests via the shared client through a series of async tasks.

This error only appears to occur when i @inject the service that's using the HttpClient. If i instantiate a local instance in the component on init, it all works fine as well. So seems like some sort of bug with injecting.

[SteveSandersonMS]

Thanks for reporting it. Since this doesn't happen in default cases, we'll need some minimal repro code to understand what's different in your scenario.

[mkArtakMSFT]

Hi. We're closing this issue as we have heard no response from you for some time now. If you have more details and are encountering this issue please add a new reply and re-open the issue.

[MoimHossain]

Hi @mkArtakMSFT , the issue is indeed there. Here's how it can be reproduced:

1. File>New>Blazor Project
2. Create a typed client:

    public class GitHub
    {
        private readonly HttpClient _client;
        public GitHub(HttpClient client)
        {
            client.BaseAddress = new Uri("https://api.github.com/");
            client.DefaultRequestHeaders.Add("Accept",
                "application/vnd.github.v3+json");
            client.DefaultRequestHeaders.Add("User-Agent",
                "HttpClientFactory-Sample");
            this._client = client;
        }

        public async Task<string> GetAspNetDocsIssues()
        {
            var response = await _client.GetAsync(
                $"{_client.BaseAddress}repos/aspnet/AspNetCore.Docs/issues?state=open&sort=created&direction=desc");
            response.EnsureSuccessStatusCode();
            var result = await response.Content.ReadAsStringAsync();
            return result;
        }
    }

1. Configure DI in Startup.cs as:

services.AddHttpClient<GitHub>();

1. Now in FetchData.rajor - Inject the typed client

@inject GitHub Git

1. Finally, invoking the API:

    protected async override Task OnAfterRenderAsync()
    {
        // THIS WILL FAIL !!!
        await Git.GetAspNetDocsIssues();
        await base.OnAfterRenderAsync();
    }

Maybe reopen the issue?

[SteveSandersonMS]

This fails because AddHttpClient doesn't supply HttpClient instances that use the correct message handler (WebAssemblyHttpMessageHandler).

This will only be fixed once we implement #10489. So rather than reopening this issue, we can regard it as covered by #10489.

[SteveSandersonMS]

BTW as a workaround, I think you can do something like:

services
    .AddHttpClient<IMyClient, MyClient>()
    .ConfigurePrimaryHttpMessageHandler<WebAssemblyHttpMessageHandler>();

[MoimHossain]

Thanks @SteveSandersonMS, workaround works, Cheers!

[amithegde]

I came here while trying to use autorest generated SDK. Turns out HttpClient can be injected to autorest generated SDK from blazor and it just works fine. Here is the approach: https://stackoverflow.com/a/49953565/147613. Leaving it hear for anyone who faces same issue.