[FIXED] Problem with using Depends() from FastAPI with AsyncGenerator

Issue

I'm trying to get client connection to Redis in my application

def create_app():
    app = FastAPI(docs_url='/')
    task_queue: Queue

    @app.on_event("startup")
    async def startup_event(redis_conn: redis.asyncio.Redis = Depends(get_async_redis_client)):
        nonlocal task_queue
        task_queue = Queue("task_queue", connection=redis_conn)


    @app.post("/add_data")
    async def add_data(data: str):
        task_queue.enqueue(process_data, data)
        return {"message": "Book in processing"}

    @app.get("/get_data")
    async def get_data():
        return {"data": "kek"}

    return app


def main():
    uvicorn.run(
        f"{__name__}:create_app",
        host='0.0.0.0', port=8888,
        reload=True
    )


if __name__ == '__main__':
    print("")
    main()

Generator get_async_redis_client got from:

redis_pool = redis.asyncio.ConnectionPool.from_url(f"redis://{REDIS_HOST}:{REDIS_PORT}")


async def get_async_redis_client() -> AsyncGenerator[Redis, None]:
    async with Redis.from_pool(redis_pool) as client:
        yield client

When i do POST request to "\add_data" i got an error

File "C:\Users\Степан\PycharmProjects\testToBaum\src\main.py", line 28, in add_data
    task_queue.enqueue(process_data, data)
  File "C:\Users\Степан\PycharmProjects\testToBaum\venv\Lib\site-packages\rq\queue.py", line 972, in enqueue
    return self.enqueue_call(
           ^^^^^^^^^^^^^^^^^^
  File "C:\Users\Степан\PycharmProjects\testToBaum\venv\Lib\site-packages\rq\queue.py", line 721, in enqueue_call
    return self.enqueue_job(job, pipeline=pipeline, at_front=at_front)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Степан\PycharmProjects\testToBaum\venv\Lib\site-packages\rq\queue.py", line 1095, in enqueue_job
    return self._enqueue_job(job, pipeline=pipeline, at_front=at_front)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Степан\PycharmProjects\testToBaum\venv\Lib\site-packages\rq\queue.py", line 1111, in _enqueue_job
    pipe = pipeline if pipeline is not None else self.connection.pipeline()
                                                 ^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'Depends' object has no attribute 'pipeline'

I thought that when i'm using Depends() with generator then "redis_conn" must be redis.asyncio.Redis object.

The same case with postgresql connection worked before

Solution

Unfortunately you can't use dependencies in startup event.

You can use this as a workaround:

def create_app():
    task_queue: Queue

    async def lifespann(app):
        get_async_redis_client_real = app.dependency_overrides.get(get_async_redis_client, get_async_redis_client)
        async for redis_conn in get_async_redis_client_real():
            nonlocal task_queue
            task_queue = Queue("task_queue", connection=redis_conn)
            yield

    app = FastAPI(
        docs_url='/',
        lifespan=lifespann
    )


    @app.post("/add_data")
    async def add_data(data: str):
        task_queue.enqueue(process_data, data)
        return {"message": "Book in processing"}

    @app.get("/get_data")
    async def get_data():
        return {"data": "kek"}

    return app

Answered By - Yurii Motov