mongoengine atomic get_or_create using findAndModify

atomic_get_or_create.py

#!/usr/bin/env python3

from mongoengine import Document, IntField, StringField, connect
connect('test')

class ChatUser(Document):

    _access = IntField() # internal access counter
  
    chat_id = IntField(required=True, unique=True)
    platform = StringField(required=True, choices=('telegram', 'facebook'), default='telegram')
    name = StringField(required=True)
    state = StringField()

    @classmethod
    def get_or_create(cls, query, new=None):

        setOnInsert = cls().to_mongo().to_dict()
        if new:
            setOnInsert.update(new)

        update = {'$inc': {'_access': 1}}
        if setOnInsert:
            update['$setOnInsert'] = setOnInsert

        res = cls._get_collection().find_one_and_update(
            query, update, return_document=True, upsert=True)

        if res['_access'] == 1:
            print("create")
        else:
            print("get")

        res['id'] = res.pop('_id')
        return cls(**res)
        
ChatUser.get_or_create(query={'chat_id': 1234}, new={'name': 'user'})
ChatUser.get_or_create(query={'chat_id': 1234}, new={'name': 'user'})