Support UUID representation

[pcorpet]

As of pymongo v4+, it should error if used with default representation (Unspecified).

We could implement a first feature that accepts custom representation, and only fails (NotImplementedError) if writing/reading/comparing in different uuid representations for the same server. Otherwise if it's not Unspecified, we could handle UUID the same way we did before pymongo v4.

[Kalbi]

Hello, I'm bumping this as I believe not being able to specify UUID representation w/ mongomock is the reason for my tests to be breaking with pymongo v4.

I tried sanity checking this by making some DB queries, updates, and additions, and was successful. I am currently using mongoengine v0.24.0 which falls back to PYTHON_LEGACY, which is presumably why it works. I am only failing my unit tests.

Here is a stack trace from a breaking test, which leads me to believe that mongomock is the culprit:

lib/mongo/mongo_nodes.py:188: in save
    return super().save(*args, **kwargs)
../../../../.local/share/virtualenvs/services-5Tycw3tD/lib/python3.9/site-packages/mongoengine/document.py:416: in save
    object_id = self._save_create(doc, force_insert, write_concern)
../../../../.local/share/virtualenvs/services-5Tycw3tD/lib/python3.9/site-packages/mongoengine/document.py:481: in _save_create
    object_id = wc_collection.insert_one(doc).inserted_id
../../../../.local/share/virtualenvs/services-5Tycw3tD/lib/python3.9/site-packages/mongomock/collection.py:463: in insert_one
    return InsertOneResult(self._insert(document, session), acknowledged=True)
../../../../.local/share/virtualenvs/services-5Tycw3tD/lib/python3.9/site-packages/mongomock/collection.py:514: in _insert
    BSON.encode(data, check_keys=True)
../../../../.local/share/virtualenvs/services-5Tycw3tD/lib/python3.9/site-packages/bson/__init__.py:1150: in encode
    return cls(encode(document, check_keys, codec_options))
../../../../.local/share/virtualenvs/services-5Tycw3tD/lib/python3.9/site-packages/bson/__init__.py:871: in encode
    return _dict_to_bson(document, check_keys, codec_options)

Can someone confirm?

[elanou]

pymongo 4.0+ requires you to set uuidRepresentation along with other options on client initialization. This is not supported in mongomock and breaks unittests that once relied on the legacy behavior of uuidRepresentation 3 (pythonLegacy).

This should be added along side other kwarg options such as 'tzinfo' and 'tz_aware'.

Poking around I was able to make it work by updating collection.py to pass codec_options when it calls bson.encode. Also had to update the code in the chain of calls that initialize the codec_options for the connection.

[joshuashaffer]

@elanou Is this similar to the hack you did?

https://github.com/joshuashaffer/mongomock-uuid-pymongo4/commit/64a5551629bbf2506004eac47ce27daf54d094fc

[joshuashaffer]

https://github.com/joshuashaffer/mongomock-uuid-pymongo4/commit/5944358bdc3577f5515dcbfd689728ca9a4834b4

Need to propigate codec_options in a few more places...

[till-goodbytz]

Seeing this open for some time and not knowing when the fixes will be merged, here is another suggestion I use, so I can continue using the released version.

import unittest.mock as mock
from uuid import UUID
from bson.binary import Binary, UuidRepresentation, UUID_SUBTYPE

def side_effect_mongo_mock_from_uuid(uuid: UUID, uuid_representation = UuidRepresentation.STANDARD):
    """Override (Mock) the bson.binary.Binary.from_uuid function to work for mongomock

    Code is copy pasted from the original function,
    but `uuid_representation` is ignored and only code parts as if
    uuid_representation == UuidRepresentation.STANDARD are used
    """
    if not isinstance(uuid, UUID):
        raise TypeError("uuid must be an instance of uuid.UUID")

    subtype = UUID_SUBTYPE
    payload = uuid.bytes

    return Binary(payload, subtype)

@pytest.fixture()
def mongo_uuid(monkeypatch):
    with mock.patch.object(Binary, 'from_uuid', side_effect=side_effect_mongo_mock_from_uuid):
        yield

Probably the same is requried for the as_uuid function

If using this, be careful as other errors may not be noticed by the test. e.g. uuid_representation having an invalid value is never checked here.