How to change the date when autosaving an object to the database using mock and SQLAlchemy?

Question

ORM

Good afternoon. In my Flask application, I use SQLAlchemy. I have a model like this:

class Entry(db.Model):
    __tablename__ = 'entries'
    name = db.Column(db.String(100))
    created = db.Column(db.DateTime(), default=datetime.now())
    updated = db.Column(db.DateTime(), default=datetime.now(), onupdate=datetime.now())

In my tests, I try to simulate saving to the database with the specified time. In the example below, I'm using freezegun , but the test doesn't work that way. The current creation time is returned.

class ViewTestCase(AppliactionTestCase):
    def test(self):
        with freeze_time("2014-06-01 16:00:00"):
            db.session.add(Entry(name="title"))
            db.session.commit()
        entry = db.session.query(Entry).first()
        self.assertEqual(entry.created, datetime(2014, 6, 1, 16, 0, 0))
        self.assertEqual(entry.updated, datetime(2014, 6, 1, 16, 0, 0))

        with freeze_time("2014-07-01 17:00:00"):
            entry.name = 'edited title'
            db.session.add(entry)
            db.session.commit()

       entry = db.session.query(Entry).first()
       self.assertEqual(entry.created, datetime(2014, 6, 1, 16, 0, 0))
       self.assertEqual(entry.created, datetime(2014, 7, 1, 17, 0, 0))

I also tried to patch with mock so that db.DateTime.python_type would return FakeDatetime, but the result is the same.
I haven't delved deeply into SQLAlchemy's design. If anyone has encountered this, tell me what needs to be redefined or how this issue can be resolved.