Using mongodb session transaction

Hello,

I want to use transaction based on Umongo document instance, could we use a custom session in the commit method?

The following is the way that I use on the motor without Umongo:

async with await db_client.start_session() as session:
    async with session.start_transaction():
        session.collection.insert_one({myobject:"objectvalue"})

[lafrech]

Mongo 4 introduces transactions. We use it in our application. To do so we had to override a lot of methods in pymongo driver to pass session through all methods. (About 300 LoC.)

We did it in a clumsy way. It could probably be achieved more elegantly. Perhaps using context variables.

I’m open to the idea. Just never got the time to do it correctly enough to merge it in umongo.

[lafrech]

BTW, thanks @touilleMan for suggesting the use of context variables for this at PyConFR 2019.