python-dependency-injector/examples/providers/context_local_resource.py

import asyncio
from uuid import uuid4

from fastapi import Depends, FastAPI

from dependency_injector import containers, providers
from dependency_injector.wiring import Closing, Provide, inject


class AsyncSessionLocal:
    def __init__(self):
        self.id = uuid4()

    async def __aenter__(self):
        print("Entering session !")
        return self

    async def __aexit__(self, exc_type, exc_val, exc_tb):
        print("Closing session !")

    async def execute(self, user_input):
        await asyncio.sleep(0.1)
        return f"Executing {user_input} in session {self.id}"


class APIRepository:
    @inject
    async def execute(self, user_input, db_session: AsyncSessionLocal = Provide["db_session"]):
        return await db_session.execute(user_input)


app = FastAPI()


class Container(containers.DeclarativeContainer):
    db_session = providers.ContextLocalResource(AsyncSessionLocal)
    api_repository = providers.Factory(APIRepository)


@app.get("/")
@inject
async def index(
        db: AsyncSessionLocal = Depends(Closing[Provide["db_session"]]),
        api_repository: APIRepository = Depends(Provide["api_repository"]),
):
    user_input = "SELECT 1"
    res = await db.execute(user_input)
    res_from_repo = await api_repository.execute(user_input=user_input)
    assert res == res_from_repo

    return str(res)


if __name__ == "__main__":
    import uvicorn

    container = Container()
    container.wire(modules=["__main__"])
    uvicorn.run(app, host="localhost", port=8000)
    container.unwire()