Juan Gutierrez

Looks like if you use a version of pip < 21.x , installs get hosed. pip 19 yells at you about not supporting `pep 517`: ``` pip._vendor.pep517.wrappers.BackendUnavailable You are using...

I've been playing around with an implementation for option 3, without getting very deep into the guts of mongoengine (yet 😈 ) and I have some interface/usage thoughts/questions based on...

I deleted my last comment regrading coupling of databases/connections 🤦 - missed something simple and I went down a rabbit hole - sorry for the noise ❤️

Something important for us to keep in mind: [pymongo is extremely upfront that sessions are neither fork-safe nor thread-safe](https://pymongo.readthedocs.io/en/stable/api/pymongo/client_session.html#pymongo.client_session.ClientSession). At minimum the docs would need to mirror this, but from...

Whoops - forgot to give travis the "replicaSet" treatment!

OK - I see what's going on - [per the docs](https://docs.mongodb.com/manual/core/transactions/#transactions-api) > _In MongoDB 4.2 and earlier, you cannot create collections in transactions. Write operations that result in document inserts_...

Digging through the repo, looks like this would be an acceptable approach.

No apologies necessary! Thanks for the feedback - I'll try to address them as soon as I can. Great idea about thread locals, btw!

OK - I think this is ready for another review round! 💪

Thank you for the feedback @EVA-08 - I've added at minimum a placeholder for users to provide a `dict` of kwargs they might need for [start_session](https://pymongo.readthedocs.io/en/stable/api/pymongo/mongo_client.html#pymongo.mongo_client.MongoClient.start_session) or [start_transaction](https://pymongo.readthedocs.io/en/stable/api/pymongo/client_session.html#pymongo.client_session.ClientSession.start_transaction) We'll see...