In decorator function, Is there a way to apply the session used by decorator wrapper function to the repository code?

Question

First of all, I'm so sorry to write an ambiguous title.

My situation is like below.

I wanted to use Transactional decorator (like @Transactional in Spring)

But in order to use transaction in PyMongo,

it need to use the session of wrapper function like Repository function(mongo_user_repository.save()).

(docs - https://pymongo.readthedocs.io/en/stable/api/pymongo/client_session.html)

So, Is there any way to get session of wrapper function in Service functions or some other way to use transactional decorator in Service functions?

I made decorator,

class MongoDB:
    def __init__(self):
        self.__client = MongoClient(
            DB_URL,
            tlsCAFile=certifi.where()
        )

    def close(self):
        self.__client.close()

    def transactional(self, origin_func):
        def wrapper_func(*args, **kwargs):
            with self.__client.start_session() as session:
                with session.start_transaction():
                    return origin_func(*args, **kwargs)

        return wrapper_func

And wanted to use like this in service code.

class UserService:
    def __init__(
        self,
        mongo_user_repository: MongoUsersRepository,
    ):
        self.__mongo_user_repository: MongoUsersRepository = mongo_user_repository

    @mongodb.transactional
    def save(self, user_create_request: UserCreateRequestDto):
        mongo_user = MongoUsers.from_dto(user_create_request=user_create_request)

        self.__mongo_user_repository.save(
            mongo_user=mongo_user,
            session=session
        )

Answer 1

You can make mongodb.transactional call the wrapped function with session as an additional argument:

def transactional(self, origin_func):
    def wrapper_func(*args, **kwargs):
        with self.__client.start_session() as session:
            with session.start_transaction():
                return origin_func(*args, session=session, **kwargs)

    return wrapper_func

so that the decorated service function can take session as an argument:

@mongodb.transactional
def save(self, user_create_request: UserCreateRequestDto, session):
    mongo_user = MongoUsers.from_dto(user_create_request=user_create_request)

    self.__mongo_user_repository.save(
        mongo_user=mongo_user,
        session=session
    )