How to serialize umongo documents

Question

Let's say I have the following example:

from datetime import datetime
import dill
from pymongo import MongoClient
from umongo import Instance, Document, fields, validate

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

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

    class Meta:
        collection = db.user

User.ensure_indexes()

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

found_goku = User.find_one({"email": '[email protected]'})
with open("dumped.dil", "wb") as out_file:
    dill.dump(found_goku, out_file)

This results in the following error on dill.dump:

_pickle.PicklingError: Can't pickle <Implementation class 'tests.test_serialize_umongo.User'>: it's not found as tests.test_serialize_umongo.User

I understand that I can not simply pickle a User because I can not pickle the database instance. I want to pickle a user to a Dict using umongo's dump and overriding __getstate__, but I do not know how to get around this it's not found aserror.

Answer 1

If I understand you correctly, I believe what you're looking for is the following. In essence, we're using the document's own dump() method to pass the serialized document as the user to be pickled. The only difference here is the last line: dill.dump(found_goku.dump(), out_file):

from datetime import datetime
import dill
from pymongo import MongoClient
from umongo import Instance, Document, fields, validate

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

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

    class Meta:
        collection = db.user

User.ensure_indexes()

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

found_goku = User.find_one({"email": '[email protected]'})
with open("dumped.dil", "wb") as out_file:
    dill.dump(found_goku.dump(), out_file)