How to inject service for SignalR hub

Question

In my ASP.NET Core 7 MVC application, in startup.cs hub service is injected like this:

public void ConfigureServices(IServiceCollection services)
{
    // ...
    services.AddScoped<IHubContext<OstupultHub>>();
}

Running the application throws an exception

System.ArgumentException HResult=0x80070057
Cannot instantiate implementation type 'Microsoft.AspNetCore.SignalR.IHubContext1[Store.Hubs.OstupultHub]' for service type 'Microsoft.AspNetCore.SignalR.IHubContext1[Store.Hubs.OstupultHub]'

Source=Microsoft.Extensions.DependencyInjection
StackTrace:
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteFactory.Populate() in /_/src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/CallSiteFactory.cs:line 68 ...

How to fix this so that hub can be used in MVC controller constructor like

public MyController(IHubContext<OstupultHub> hubContext ) { ...

Hub class is defined as

using Microsoft.AspNetCore.SignalR;
namespace Store.Hubs;

public class OstupultHub : Hub
{  ... 
}

According to

https://learn.microsoft.com/en-us/aspnet/core/signalr/hubcontext?view=aspnetcore-7.0

it should work.

Currently I'm using in controller constructor IServiceProvider

public OstupultController(IServiceProvider _provider )
  {
    provider = _provider;
  }

and then in controller

  public async Task<ContentResult> ReceiveLogFile()
  {
    var pultHub = provider.GetRequiredService<IHubContext<OstupultHub>>();
    await pultHub.Clients.All.SendAsync("sendLogFileMessage");
    return new ContentResult() { Content ="sent" };
  }

Looking for use service directly like other servies.

Answer 1

service is injected as services.AddScoped<IHubContext<OstupultHub>>();

AFAIK you don't need to register hubs this way. Just call services.AddSignalR() in the ConfigureServices and MapHub<OstupultHub>(...); in the Configure.