AddHostedService does not register specified Type Parameter in DI container #53831
Description
Description
class FooService : IHostedService
{
public FooService() {}
/* ... */
}
class BarService : IHostedService
{
public BarService(FooService foo) {}
/* ... */
}
services.AddHostedService<FooService>(); // works
services.AddHostedService<BarService>(); // crashes when because DI container does not find FooServiceThe issue is quite straight forward in the .NET source code because the THostedService is not registered but instead a IHostedService ...
public static IServiceCollection AddHostedService<THostedService>(this IServiceCollection services)
where THostedService : class, IHostedService
{
services.TryAddEnumerable(ServiceDescriptor.Singleton<IHostedService, THostedService>());
return services;
}The common workaround seems to be like
services.AddSingleton<FooService>();
services.AddSingleton<BarService>();
services.AddHostedService(sp => sp.GetService<FooService>());
services.AddHostedService(sp => sp.GetService<BarService>());My expectation was clearly, that the type I register with a ServiceCollection.Add* function later can be retrieved. I lost several hours due to this until I found the answer somewhere on StackOverflow.
Configuration
- .NET 5
- OS/Arch: Does not matter
Regression?
No
Other information
If the vote is not to double register the service (I assume the IHostedService is needed for the host logic), I would at least propose to add a warning in the documentation and maybe the function inline documentation.