[Sqlalchemy-tickets] Issue #4048: undefer_group() from relationship path has no effect (zzzeek/sqlalchemy)

[Michael B. <iss...@bi...>]

New issue 4048: undefer_group() from relationship path has no effect
https://bitbucket.org/zzzeek/sqlalchemy/issues/4048/undefer_group-from-relationship-path-has

Michael Bayer:

in 1.1.  in 1.2 the lazy load also fails entirely:


```
#!python

    def test_undefer_group_from_relationship(self):
        users, items, order_items, Order, Item, User, orders = \
            (self.tables.users,
             self.tables.items,
             self.tables.order_items,
             self.classes.Order,
             self.classes.Item,
             self.classes.User,
             self.tables.orders)

        mapper(Item, items, properties=dict(
            description=deferred(items.c.description)))
        mapper(User, users, properties=dict(
            orders=relationship(Order, order_by=orders.c.id)))
        mapper(
            Order, orders, properties=util.OrderedDict([
                ('items', relationship(Item, secondary=order_items)),
                ('userident', deferred(orders.c.user_id, group='primary')),
                ('description', deferred(orders.c.description,
                 group='primary')),
                ('opened', deferred(orders.c.isopen, group='secondary'))
            ])
        )

        sess = create_session()
        q = sess.query(User).filter(User.id == 7).options(
            defaultload(User.orders).undefer_group('primary')
        )

        def go():
            result = q.all()
            o2 = result[0].orders[1]
            eq_(o2.opened, 1)
            eq_(o2.userident, 7)
            eq_(o2.description, 'order 3')
        self.assert_sql_count(testing.db, go, 1)

```