How to create child actors with dependency injection

[Kosntantin]

I want to use akka for concurrent message processing. I am working with objects called Fixture. My design is to have a supervisor actor that gets all the messages and then routes them to another actor that handles all messages for the specific Fixture. To do this I have a dictionary of <FixtureID,IActorRef> in the supervisor actor. Naturally, if the supervisor receives a message for a Fixture that currently has no IActorRef, the supervisor needs to create a child actor and add it the dictionary. This is where I run into trouble. I am unable to create a child actor because it cannot resolve the dependencies.

This is how I register the supervising actor so I can pass it to the class that will send him the messages:

services.AddSingleton<IActorRef>(sp =>
                {
                    var bootstrap = BootstrapSetup.Create();
                    var di = DependencyResolverSetup.Create(sp);
                    var actorSystemSetup = bootstrap.And(di);
                    var _actorSystem = ActorSystem.Create("AspNetDemo", actorSystemSetup);
                    var resolver = DependencyResolver.For(_actorSystem);
                    var props = resolver.Props<SupervisingActor>();

                    return _actorSystem.ActorOf(props, "supervisor");
                });

This is how I create child actors in the supervisor:
Context.ActorOf(Context.DI().Props<FixtureActor>(), $"FixtureActor{message.Id}");
The supervisor actor is created successfully but when it tries to spawn a child actor it throws this error: 'The Dependency Resolver has not been configured yet'

My code is based on this: https://getakka.net/articles/actors/dependency-injection.html Note: I do not want to use another DI Container.

[Arkatufus]

@Kosntantin
I'm assuming you're using ASP.NET? Which version is it?
Which version of Akka.NET are you using?
Is there a limitation that restricts you to use the deprecated Akka.DI package? can you switch to the new Akka.DependencyInjection package?
Which Akka.DI package are you using?

[Kosntantin]

It is .NET 6 and the Akka version is 1.4.37. It is a Worker service, so still a HostedService but not ASP. I am using the new Akka.DependencyInjection package to create the supervisor actor but I am not sure how to create the child actors using the package. This is why I used the depricated. I have nothing that restricts me to using the old pakcage. Can you show me how to use the new one to create child actors?

[Arkatufus]

I think you need to re-arrange everything, the way you're setting everything up is not quite safe.
Here's an example project that uses Akka.Hosting and Akka.DependencyInjection in a safe way, the ActorSystem is already wrapped inside a IHostedService and its life cycle is properly hooked into the IHost life cycle:

https://github.com/Arkatufus/Akka.Net.Samples/tree/master/Akka.Hosting/HostedService

[Arkatufus]

cc @Kosntantin

[valeriob]

Thanks for the link to the example, I'm having problems doing the same thing with a ShardedRegion, but I do not understand how to create an actor Props with both DI and passing the entityId
https://petabridge.com/blog/intro-akka-hosting/

Thanks

EDIT:
i was able to make it work via
compositePropsFactory: (system, registry) => s => DependencyResolver.For(system).Props(s)
is it correct ?

[Aaronontheweb]

@valeriob that is correct!