container.init_resources() is not awaitable; it's None

[skewty]

Python 3.9 on Windows 10 system.

Traceback (most recent call last):
  File "C:\proj\grandstream-spectralink\src\__main__.py", line 17, in <module>
    asyncio.run(run())
  File "C:\Python39\lib\asyncio\runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "C:\Python39\lib\asyncio\base_events.py", line 642, in run_until_complete
    return future.result()
  File "C:\proj\grandstream-spectralink\src\__main__.py", line 10, in run
    await container.init_resources()
TypeError: object NoneType can't be used in 'await' expression

Process finished with exit code 1

async def run():
    container = Container()
    await container.init_resources()
    try:
        await container.service()
    finally:
        await container.shutdown_resources()


asyncio.run(run())

class Container(containers.DeclarativeContainer):
    msg_queue = providers.Singleton(
        asyncio.Queue,
        maxsize=10,
    )

also tried this variation thinking it may not recognize the async Queue as needing an event loop:

async def async_create_queue(*args, **kwargs):
    return asyncio.Queue(*args, **kwargs)

class Container(containers.DeclarativeContainer):
    msg_queue = providers.Singleton(
        async_create_queue,
        maxsize=10,
    )

What's the trick to get container.init_resources() to not return None?

[rmk135]

Hi @skewty ,

Please use providers.Resource instead of providers.Singleton. Method container.init_resources() inits only resource providers.

[skewty]

Thanks for the correction. I switched them to Resource as per your suggestion but I still can't await container.init_resources() (it is still None). Is the type hint just wrong? How do I get container.init_resources() to be awaitable?

[rmk135]

Hi @skewty ,

Could you provide a code sample for debugging?

[skewty]

import asyncio
from dependency_injector import containers

async def async_function():
    await asyncio.sleep(0)

class Container(containers.DeclarativeContainer):
    foo = async_function()  # makes container.init_resources() and shutdown_resources() async

async def main():
    container = Container()
    await container.init_resources()
    await container.shutdown_resources()

asyncio.run(main())

Traceback (most recent call last):
  File "async_test.py", line 12, in main
    await container.init_resources()

TypeError: object NoneType can't be used in 'await' expression
sys:1: RuntimeWarning: coroutine 'async_function' was never awaited

[kjagiello]

You forgot to use the Resource provider.

import asyncio
from dependency_injector import containers, providers

async def async_function():
    await asyncio.sleep(0)
    yield your_resource

class Container(containers.DeclarativeContainer):
    foo = providers.Resource(async_function)

async def main():
    container = Container()
    await container.init_resources()
    await container.shutdown_resources()

asyncio.run(main())

See the documentation and the examples here.

But overall, looking at your original example, it doesn't look like you need a resource at all. So this should be enough in your case:

class Container(containers.DeclarativeContainer):
    msg_queue = providers.Singleton(
        asyncio.Queue,
        maxsize=10,
    )

async def run():
    container = Container()
    queue = container.msg_queue()