Allow to create request scopes outside of the middleware

[soldag]

I started to implement something very similar to this project on my own, but was very happy to find this nice little library, which almost does all the stuff I need in order to use injector in my FastAPI application. So thanks for the work first of all!

However, it's lacking one particular feature: It would be great if there's a possibility to create request scopes also outside of the middleware. Background of this is that in my application I need to process messages I get from a message queue. Same as for requests it would be nice if it's possible to scope the lifetime of services to the handling of a single message. I could imagine there are more, similar cases where this might be helpful, for example background tasks (i.e. celery) or cronjobs. For sure I could write my own scope for this, but then I would more or less need to duplicate all of your work, so I thought it would make more sense to integrate it directly into your library.

To achieve this, I moved the logic of assigning request ids from the InjectorMiddleware to a new class called RequestScopeFactory, which allows create request scopes also outside the middleware. This could then be used for example like:

class MessageHandler:
    def __init__(self, request_scope_factory: Inject[RequestScopeFactory]) -> None:
        self.request_scope_factory = request_scope_factory

    async def handle(self, message: Any) -> None:
        with self.request_scope_factory.create_scope():
            # process message

What do you think about this?

[matyasrichter]

Hi Sören!
Sorry for the delay.

This looks great, thanks for the contribution! Looks like CI is broken, but that seems unrelated to your changes. I will merge your PR when I figure out what's wrong with it, but I'm a bit busy at the moment.

[soldag]

I actually had the same problem also when I wanted to run pre-commit locally. Looks like the issue can be fixed by updating isort (home-assistant/core#86892 (comment)). It now works for me. I pushed the change to my branch so once you approve the workflow execution we'll see if it also fixes CI.

[matyasrichter]

I will fix things up in #13 so that you can rebase your branch.

[matyasrichter]

I've merged this and created a new release, https://github.com/matyasrichter/fastapi-injector/releases/tag/0.5.0. Thanks for your PR!