State of parent container is not preserved in the child

[michael-rubel]

In "Scoped Container" feature, the state of previously registered objects is not preserved in the child.

Boot time (Uvicorn server start time):

class CoreServiceProvider(ServiceProvider):
    def register(self):
        self.container.register(PipeRegistry, scope=Scope.singleton)

class PipelineServiceProvider(ServiceProvider):
    def __init__(
        self,
        container: ServiceContainer,
        pipe_registry: PipeRegistry,
    ):
        super().__init__(container)

        self.pipe_registry = pipeline_registry

    def register(self):
        self.pipe_registry.register(MyFirstActionPipe)
        self.pipe_registry.register(MySecondActionPipe)

Request:

@routes.post("/stream")
async def stream(request: Request) -> EventSourceResponse:
    container: ServiceContainer = request.app.container.child() # <-- created a child here

    print(container)

    await container.resolve(RequestBootstrapper).bootstrap(request)

    ...

class RequestBootstrapper:
    def __init__(
        self,
        container: ServiceContainer,
        pipe_registry: PipeRegistry,
    ):
        self.container = container
        print(self.container)

        self.pipe_registry = pipe_registry
        print("Pipes: ", self.pipe_registry.pipes())

        ....

Object IDs are the same (result of prints):
<core.dependency_injection.container.ServiceContainer object at 0x75671915cf50>
<core.dependency_injection.container.ServiceContainer object at 0x75671915cf50>

Result of self.pipe_registry.pipes() is [] empty. Pipes are not registered, parent container's state is lost in the child.

[bobthemighty]

I don't know what any of these objects are, so it's a little hard for me to understand the problem here. You mean that the singleton dependency isn't shared between the child and parent?

[michael-rubel]

Yes, singletons are completely new, so the state of the parent's objects is lost. I think sharing state once (when creating a child) makes sense because you want to have access to shared registries from the parent (from the server bootstrapping stage) while using an isolated child container inside the request.

[bobthemighty]

There's a cache for singletons, held in the container, my guess is that because the dep isn't in that cache in the child, it ends up delegating back to the parent. Clear bug, which I was semi-thinking about anyway.