import datetime as dt
from pymongo import MongoClient
from umongo import Document, fields, validate
from umongo.frameworks import PyMongoInstance

db = MongoClient().test
instance = PyMongoInstance(db)

@instance.register
class User(Document):
    email = fields.EmailField(required=True, unique=True)
    birthday = fields.DateTimeField(validate=validate.Range(min=dt.datetime(1900, 1, 1)))
    friends = fields.ListField(fields.ReferenceField("User"))

    class Meta:
        collection_name = "user"

# Make sure that unique indexes are created
User.ensure_indexes()

goku = User(email='[email protected]', birthday=dt.datetime(1984, 11, 20))
goku.commit()
vegeta = User(email='[email protected]', friends=[goku])
vegeta.commit()

vegeta.friends
# <object umongo.data_objects.List([<object umongo.dal.pymongo.PyMongoReference(document=User, pk=ObjectId('5717568613adf27be6363f78'))>])>
vegeta.dump()
# {id': '570ddb311d41c89cabceeddc', 'email': '[email protected]', friends': ['570ddb2a1d41c89cabceeddb']}
User.find_one({"email": '[email protected]'})
# <object Document __main__.User({'id': ObjectId('570ddb2a1d41c89cabceeddb'), 'friends': <object umongo.data_objects.List([])>,
#                                 'email': '[email protected]', 'birthday': datetime.datetime(1984, 11, 20, 0, 0)})>

$ pip install umongo           # This installs umongo with pymongo
$ pip install my-mongo-driver  # Other MongoDB drivers must be installed manually

$ pip install umongo[motor]
$ pip install umongo[txmongo]
$ pip install umongo[mongomock]