sqlalchemy/test/orm/test_subquery_relations.py

from sqlalchemy.test.testing import eq_, is_, is_not_
from sqlalchemy.test import testing
from sqlalchemy.test.schema import Table, Column
from sqlalchemy import Integer, String, ForeignKey, bindparam
from sqlalchemy.orm import backref, subqueryload, subqueryload_all, \
                mapper, relationship, clear_mappers,\
                create_session, lazyload, aliased, joinedload,\
                deferred, undefer
from sqlalchemy.test.testing import eq_, assert_raises
from sqlalchemy.test.assertsql import CompiledSQL
from test.orm import _base, _fixtures
import sqlalchemy as sa

class EagerTest(_fixtures.FixtureTest, testing.AssertsCompiledSQL):
    run_inserts = 'once'
    run_deletes = None
    
    @testing.resolve_artifact_names
    def test_basic(self):
        mapper(User, users, properties={
            'addresses':relationship(
                            mapper(Address, addresses), 
                            order_by=Address.id)
        })
        sess = create_session()
        
        q = sess.query(User).options(subqueryload(User.addresses))
        
        def go():
            eq_(
                    [User(id=7, addresses=[
                            Address(id=1, email_address='jack@bean.com')])],
                    q.filter(User.id==7).all()
            )
        
        self.assert_sql_count(testing.db, go, 2)
        
        def go(): 
            eq_(
                self.static.user_address_result, 
                q.order_by(User.id).all()
            )
        self.assert_sql_count(testing.db, go, 2)

    @testing.resolve_artifact_names
    def test_from_get(self):
        mapper(User, users, properties={
            'addresses':relationship(
                            mapper(Address, addresses), 
                            order_by=Address.id)
        })
        sess = create_session()
        
        q = sess.query(User).options(subqueryload(User.addresses))
        def go():
            eq_(
                    User(id=7, addresses=[
                            Address(id=1, email_address='jack@bean.com')]),
                    q.get(7)
            )
        
        self.assert_sql_count(testing.db, go, 2)

    @testing.resolve_artifact_names
    def test_from_params(self):
        mapper(User, users, properties={
            'addresses':relationship(
                            mapper(Address, addresses), 
                            order_by=Address.id)
        })
        sess = create_session()

        q = sess.query(User).options(subqueryload(User.addresses))
        def go():
            eq_(
                    User(id=7, addresses=[
                            Address(id=1, email_address='jack@bean.com')]),
                    q.filter(User.id==bindparam('foo')).params(foo=7).one()
            )

        self.assert_sql_count(testing.db, go, 2)
        
        
    @testing.resolve_artifact_names
    def test_many_to_many(self):
        mapper(Keyword, keywords)
        mapper(Item, items, properties = dict(
                keywords = relationship(Keyword, secondary=item_keywords,
                                    lazy='subquery', order_by=keywords.c.id)))

        q = create_session().query(Item).order_by(Item.id)
        def go():
            eq_(self.static.item_keyword_result, q.all())
        self.assert_sql_count(testing.db, go, 2)

        def go():
            eq_(self.static.item_keyword_result[0:2],
                q.join('keywords').filter(Keyword.name == 'red').all())
        self.assert_sql_count(testing.db, go, 2)

        def go():
            eq_(self.static.item_keyword_result[0:2],
                (q.join('keywords', aliased=True).
                 filter(Keyword.name == 'red')).all())
        self.assert_sql_count(testing.db, go, 2)

    @testing.resolve_artifact_names
    def test_orderby(self):
        mapper(User, users, properties = {
            'addresses':relationship(mapper(Address, addresses), 
                        lazy='subquery', order_by=addresses.c.email_address),
        })
        q = create_session().query(User)
        eq_([
            User(id=7, addresses=[
                Address(id=1)
            ]),
            User(id=8, addresses=[
                Address(id=3, email_address='ed@bettyboop.com'),
                Address(id=4, email_address='ed@lala.com'),
                Address(id=2, email_address='ed@wood.com')
            ]),
            User(id=9, addresses=[
                Address(id=5)
            ]),
            User(id=10, addresses=[])
        ], q.order_by(User.id).all())

    @testing.resolve_artifact_names
    def test_orderby_multi(self):
        mapper(User, users, properties = {
            'addresses':relationship(mapper(Address, addresses), 
                            lazy='subquery', 
                            order_by=[
                                    addresses.c.email_address,
                                    addresses.c.id]),
        })
        q = create_session().query(User)
        eq_([
            User(id=7, addresses=[
                Address(id=1)
            ]),
            User(id=8, addresses=[
                Address(id=3, email_address='ed@bettyboop.com'),
                Address(id=4, email_address='ed@lala.com'),
                Address(id=2, email_address='ed@wood.com')
            ]),
            User(id=9, addresses=[
                Address(id=5)
            ]),
            User(id=10, addresses=[])
        ], q.order_by(User.id).all())

    @testing.resolve_artifact_names
    def test_orderby_related(self):
        """A regular mapper select on a single table can 
            order by a relationship to a second table"""

        mapper(Address, addresses)
        mapper(User, users, properties = dict(
            addresses = relationship(Address, 
                                        lazy='subquery',
                                        order_by=addresses.c.id),
        ))

        q = create_session().query(User)
        l = q.filter(User.id==Address.user_id).\
            order_by(Address.email_address).all()

        eq_([
            User(id=8, addresses=[
                Address(id=2, email_address='ed@wood.com'),
                Address(id=3, email_address='ed@bettyboop.com'),
                Address(id=4, email_address='ed@lala.com'),
            ]),
            User(id=9, addresses=[
                Address(id=5)
            ]),
            User(id=7, addresses=[
                Address(id=1)
            ]),
        ], l)

    @testing.resolve_artifact_names
    def test_orderby_desc(self):
        mapper(Address, addresses)
        mapper(User, users, properties = dict(
            addresses = relationship(Address, lazy='subquery',
                                 order_by=[
                                    sa.desc(addresses.c.email_address)
                                ]),
        ))
        sess = create_session()
        eq_([
            User(id=7, addresses=[
                Address(id=1)
            ]),
            User(id=8, addresses=[
                Address(id=2, email_address='ed@wood.com'),
                Address(id=4, email_address='ed@lala.com'),
                Address(id=3, email_address='ed@bettyboop.com'),
            ]),
            User(id=9, addresses=[
                Address(id=5)
            ]),
            User(id=10, addresses=[])
        ], sess.query(User).order_by(User.id).all())

    _pathing_runs = [
        ( "lazyload", "lazyload", "lazyload", 15 ),
        ("subqueryload", "lazyload", "lazyload", 12),
        ("subqueryload", "subqueryload", "lazyload", 8),
        ("joinedload", "subqueryload", "lazyload", 7),
        ("lazyload", "lazyload", "subqueryload", 12),
        ("subqueryload", "subqueryload", "subqueryload", 4),
        ("subqueryload", "subqueryload", "joinedload", 3),
    ]
#    _pathing_runs = [("subqueryload", "subqueryload", "joinedload", 3)]
#    _pathing_runs = [("subqueryload", "subqueryload", "subqueryload", 4)]

    def test_options_pathing(self):
        self._do_options_test(self._pathing_runs)
    
    def test_mapper_pathing(self):
        self._do_mapper_test(self._pathing_runs)
    
    @testing.resolve_artifact_names
    def _do_options_test(self, configs):
        mapper(User, users, properties={
            'orders':relationship(Order, order_by=orders.c.id), # o2m, m2o
        })
        mapper(Order, orders, properties={
            'items':relationship(Item, 
                        secondary=order_items, order_by=items.c.id),  #m2m
        })
        mapper(Item, items, properties={
            'keywords':relationship(Keyword, 
                                        secondary=item_keywords,
                                        order_by=keywords.c.id) #m2m
        })
        mapper(Keyword, keywords)
        
        callables = {
                        'joinedload':joinedload, 
                    'subqueryload':subqueryload
                }
        
        for o, i, k, count in configs:
            options = []
            if o in callables:
                options.append(callables[o](User.orders))
            if i in callables:
                options.append(callables[i](User.orders, Order.items))
            if k in callables:
                options.append(callables[k](User.orders, Order.items, Item.keywords))

            self._do_query_tests(options, count)

    @testing.resolve_artifact_names
    def _do_mapper_test(self, configs):
        opts = {
            'lazyload':'select',
            'joinedload':'joined',
            'subqueryload':'subquery',
        }

        for o, i, k, count in configs:
            mapper(User, users, properties={
                'orders':relationship(Order, lazy=opts[o], order_by=orders.c.id), 
            })
            mapper(Order, orders, properties={
                'items':relationship(Item, 
                            secondary=order_items, lazy=opts[i], order_by=items.c.id), 
            })
            mapper(Item, items, properties={
                'keywords':relationship(Keyword, 
                                            lazy=opts[k],
                                            secondary=item_keywords,
                                            order_by=keywords.c.id)
            })
            mapper(Keyword, keywords)
            
            try:
                self._do_query_tests([], count)
            finally:
                clear_mappers()
    
    @testing.resolve_artifact_names
    def _do_query_tests(self, opts, count):
        sess = create_session()
        def go():
            eq_(
                sess.query(User).options(*opts).order_by(User.id).all(),
                self.static.user_item_keyword_result
            )
        self.assert_sql_count(testing.db, go, count)

        eq_(
            sess.query(User).options(*opts).filter(User.name=='fred').
                    order_by(User.id).all(),
            self.static.user_item_keyword_result[2:3]
        )

        sess = create_session()
        eq_(
            sess.query(User).options(*opts).join(User.orders).
                    filter(Order.id==3).\
                    order_by(User.id).all(),
            self.static.user_item_keyword_result[0:1]
        )
        
    
    @testing.resolve_artifact_names
    def test_cyclical(self):
        """A circular eager relationship breaks the cycle with a lazy loader"""

        mapper(Address, addresses)
        mapper(User, users, properties = dict(
            addresses = relationship(Address, lazy='subquery',
                                 backref=sa.orm.backref('user', lazy='subquery'),
                                            order_by=Address.id)
        ))
        is_(sa.orm.class_mapper(User).get_property('addresses').lazy, 'subquery')
        is_(sa.orm.class_mapper(Address).get_property('user').lazy, 'subquery')

        sess = create_session()
        eq_(self.static.user_address_result, sess.query(User).order_by(User.id).all())

    @testing.resolve_artifact_names
    def test_double(self):
        """Eager loading with two relationships simultaneously, 
            from the same table, using aliases."""

        openorders = sa.alias(orders, 'openorders')
        closedorders = sa.alias(orders, 'closedorders')

        mapper(Address, addresses)
        mapper(Order, orders)

        open_mapper = mapper(Order, openorders, non_primary=True)
        closed_mapper = mapper(Order, closedorders, non_primary=True)

        mapper(User, users, properties = dict(
            addresses = relationship(Address, lazy='subquery',
                                        order_by=addresses.c.id),
            open_orders = relationship(
                open_mapper,
                primaryjoin=sa.and_(openorders.c.isopen == 1,
                                 users.c.id==openorders.c.user_id),
                lazy='subquery', order_by=openorders.c.id),
            closed_orders = relationship(
                closed_mapper,
                primaryjoin=sa.and_(closedorders.c.isopen == 0,
                                 users.c.id==closedorders.c.user_id),
                lazy='subquery', order_by=closedorders.c.id)))

        q = create_session().query(User).order_by(User.id)

        def go():
            eq_([
                User(
                    id=7,
                    addresses=[Address(id=1)],
                    open_orders = [Order(id=3)],
                    closed_orders = [Order(id=1), Order(id=5)]
                ),
                User(
                    id=8,
                    addresses=[Address(id=2), Address(id=3), Address(id=4)],
                    open_orders = [],
                    closed_orders = []
                ),
                User(
                    id=9,
                    addresses=[Address(id=5)],
                    open_orders = [Order(id=4)],
                    closed_orders = [Order(id=2)]
                ),
                User(id=10)

            ], q.all())
        self.assert_sql_count(testing.db, go, 4)

    @testing.resolve_artifact_names
    def test_double_same_mappers(self):
        """Eager loading with two relationships simulatneously, 
        from the same table, using aliases."""

        mapper(Address, addresses)
        mapper(Order, orders, properties={
            'items': relationship(Item, secondary=order_items, lazy='subquery',
                              order_by=items.c.id)})
        mapper(Item, items)
        mapper(User, users, properties=dict(
            addresses=relationship(Address, lazy='subquery', order_by=addresses.c.id),
            open_orders=relationship(
                Order,
                primaryjoin=sa.and_(orders.c.isopen == 1,
                                 users.c.id==orders.c.user_id),
                lazy='subquery', order_by=orders.c.id),
            closed_orders=relationship(
                Order,
                primaryjoin=sa.and_(orders.c.isopen == 0,
                                 users.c.id==orders.c.user_id),
                lazy='subquery', order_by=orders.c.id)))
        q = create_session().query(User).order_by(User.id)

        def go():
            eq_([
                User(id=7,
                     addresses=[
                       Address(id=1)],
                     open_orders=[Order(id=3,
                                        items=[
                                          Item(id=3),
                                          Item(id=4),
                                          Item(id=5)])],
                     closed_orders=[Order(id=1,
                                          items=[
                                            Item(id=1),
                                            Item(id=2),
                                            Item(id=3)]),
                                    Order(id=5,
                                          items=[
                                            Item(id=5)])]),
                User(id=8,
                     addresses=[
                       Address(id=2),
                       Address(id=3),
                       Address(id=4)],
                     open_orders = [],
                     closed_orders = []),
                User(id=9,
                     addresses=[
                       Address(id=5)],
                     open_orders=[
                       Order(id=4,
                             items=[
                               Item(id=1),
                               Item(id=5)])],
                     closed_orders=[
                       Order(id=2,
                             items=[
                               Item(id=1),
                               Item(id=2),
                               Item(id=3)])]),
                User(id=10)
            ], q.all())
        self.assert_sql_count(testing.db, go, 6)

    @testing.fails_on('maxdb', 'FIXME: unknown')
    @testing.resolve_artifact_names
    def test_limit(self):
        """Limit operations combined with lazy-load relationships."""

        mapper(Item, items)
        mapper(Order, orders, properties={
            'items':relationship(Item, secondary=order_items, lazy='subquery',
                order_by=items.c.id)
        })
        mapper(User, users, properties={
            'addresses':relationship(mapper(Address, addresses), 
                            lazy='subquery', 
                            order_by=addresses.c.id),
            'orders':relationship(Order, lazy='select', order_by=orders.c.id)
        })

        sess = create_session()
        q = sess.query(User)

        l = q.order_by(User.id).limit(2).offset(1).all()
        eq_(self.static.user_all_result[1:3], l)

        sess = create_session()
        l = q.order_by(sa.desc(User.id)).limit(2).offset(2).all()
        eq_(list(reversed(self.static.user_all_result[0:2])), l)

    @testing.resolve_artifact_names
    def test_one_to_many_scalar(self):
        mapper(User, users, properties = dict(
            address = relationship(mapper(Address, addresses), 
                                    lazy='subquery', uselist=False)
        ))
        q = create_session().query(User)

        def go():
            l = q.filter(users.c.id == 7).all()
            eq_([User(id=7, address=Address(id=1))], l)
        self.assert_sql_count(testing.db, go, 2)

    @testing.fails_on('maxdb', 'FIXME: unknown')
    @testing.resolve_artifact_names
    def test_many_to_one(self):
        mapper(Address, addresses, properties = dict(
            user = relationship(mapper(User, users), lazy='subquery')
        ))
        sess = create_session()
        q = sess.query(Address)

        def go():
            a = q.filter(addresses.c.id==1).one()
            is_not_(a.user, None)
            u1 = sess.query(User).get(7)
            is_(a.user, u1)
        self.assert_sql_count(testing.db, go, 2)

    @testing.resolve_artifact_names
    def test_double_with_aggregate(self):
        max_orders_by_user = sa.select([sa.func.max(orders.c.id).label('order_id')],
                                       group_by=[orders.c.user_id]
                                     ).alias('max_orders_by_user')

        max_orders = orders.select(orders.c.id==max_orders_by_user.c.order_id).\
                                alias('max_orders')

        mapper(Order, orders)
        mapper(User, users, properties={
               'orders':relationship(Order, backref='user', lazy='subquery',
                                            order_by=orders.c.id),
               'max_order':relationship(
                                mapper(Order, max_orders, non_primary=True), 
                                lazy='subquery', uselist=False)
               })

        q = create_session().query(User)

        def go():
            eq_([
                User(id=7, orders=[
                        Order(id=1),
                        Order(id=3),
                        Order(id=5),
                    ],
                    max_order=Order(id=5)
                ),
                User(id=8, orders=[]),
                User(id=9, orders=[Order(id=2),Order(id=4)],
                    max_order=Order(id=4)
                ),
                User(id=10),
            ], q.order_by(User.id).all())
        self.assert_sql_count(testing.db, go, 3)

    @testing.resolve_artifact_names 
    def test_uselist_false_warning(self):
        """test that multiple rows received by a 
        uselist=False raises a warning."""

        mapper(User, users, properties={
            'order':relationship(Order, uselist=False)
        })
        mapper(Order, orders)
        s = create_session()
        assert_raises(sa.exc.SAWarning,
                s.query(User).options(subqueryload(User.order)).all)

class OrderBySecondaryTest(_base.MappedTest):
    @classmethod
    def define_tables(cls, metadata):
        Table('m2m', metadata,
              Column('id', Integer, primary_key=True, test_needs_autoincrement=True),
              Column('aid', Integer, ForeignKey('a.id')),
              Column('bid', Integer, ForeignKey('b.id')))

        Table('a', metadata,
              Column('id', Integer, primary_key=True, test_needs_autoincrement=True),
              Column('data', String(50)))
        Table('b', metadata,
              Column('id', Integer, primary_key=True, test_needs_autoincrement=True),
              Column('data', String(50)))

    @classmethod
    def fixtures(cls):
        return dict(
            a=(('id', 'data'),
               (1, 'a1'),
               (2, 'a2')),

            b=(('id', 'data'),
               (1, 'b1'),
               (2, 'b2'),
               (3, 'b3'),
               (4, 'b4')),

            m2m=(('id', 'aid', 'bid'),
                 (2, 1, 1),
                 (4, 2, 4),
                 (1, 1, 3),
                 (6, 2, 2),
                 (3, 1, 2),
                 (5, 2, 3)))

    @testing.resolve_artifact_names
    def test_ordering(self):
        class A(_base.ComparableEntity):pass
        class B(_base.ComparableEntity):pass

        mapper(A, a, properties={
            'bs':relationship(B, secondary=m2m, lazy='subquery', order_by=m2m.c.id)
        })
        mapper(B, b)

        sess = create_session()
        def go():
            eq_(sess.query(A).all(), [
                        A(data='a1', bs=[B(data='b3'), B(data='b1'), B(data='b2')]),
                        A(bs=[B(data='b4'), B(data='b3'), B(data='b2')])
            ])
        self.assert_sql_count(testing.db, go, 2)

class SelfReferentialTest(_base.MappedTest):
    @classmethod
    def define_tables(cls, metadata):
        Table('nodes', metadata,
              Column('id', Integer, primary_key=True, test_needs_autoincrement=True),
            Column('parent_id', Integer, ForeignKey('nodes.id')),
            Column('data', String(30)))

    @testing.fails_on('maxdb', 'FIXME: unknown')
    @testing.resolve_artifact_names
    def test_basic(self):
        class Node(_base.ComparableEntity):
            def append(self, node):
                self.children.append(node)

        mapper(Node, nodes, properties={
            'children':relationship(Node, 
                                        lazy='subquery', 
                                        join_depth=3, order_by=nodes.c.id)
        })
        sess = create_session()
        n1 = Node(data='n1')
        n1.append(Node(data='n11'))
        n1.append(Node(data='n12'))
        n1.append(Node(data='n13'))
        n1.children[1].append(Node(data='n121'))
        n1.children[1].append(Node(data='n122'))
        n1.children[1].append(Node(data='n123'))
        n2 = Node(data='n2')
        n2.append(Node(data='n21'))
        n2.children[0].append(Node(data='n211'))
        n2.children[0].append(Node(data='n212'))
        
        sess.add(n1)
        sess.add(n2)
        sess.flush()
        sess.expunge_all()
        def go():
            d = sess.query(Node).filter(Node.data.in_(['n1', 'n2'])).\
                            order_by(Node.data).all()
            eq_([Node(data='n1', children=[
                    Node(data='n11'),
                    Node(data='n12', children=[
                        Node(data='n121'),
                        Node(data='n122'),
                        Node(data='n123')
                    ]),
                    Node(data='n13')
                ]),
                Node(data='n2', children=[
                    Node(data='n21', children=[
                        Node(data='n211'),
                        Node(data='n212'),
                    ])
                ])
            ], d)
        self.assert_sql_count(testing.db, go, 4)



    @testing.resolve_artifact_names
    def test_lazy_fallback_doesnt_affect_eager(self):
        class Node(_base.ComparableEntity):
            def append(self, node):
                self.children.append(node)

        mapper(Node, nodes, properties={
            'children':relationship(Node, lazy='subquery', join_depth=1,
                                    order_by=nodes.c.id)
        })
        sess = create_session()
        n1 = Node(data='n1')
        n1.append(Node(data='n11'))
        n1.append(Node(data='n12'))
        n1.append(Node(data='n13'))
        n1.children[1].append(Node(data='n121'))
        n1.children[1].append(Node(data='n122'))
        n1.children[1].append(Node(data='n123'))
        sess.add(n1)
        sess.flush()
        sess.expunge_all()

        def go():
            allnodes = sess.query(Node).order_by(Node.data).all()
            n12 = allnodes[2]
            eq_(n12.data, 'n12')
            eq_([
                Node(data='n121'),
                Node(data='n122'),
                Node(data='n123')
            ], list(n12.children))
        self.assert_sql_count(testing.db, go, 4)

    @testing.resolve_artifact_names
    def test_with_deferred(self):
        class Node(_base.ComparableEntity):
            def append(self, node):
                self.children.append(node)

        mapper(Node, nodes, properties={
            'children':relationship(Node, lazy='subquery', join_depth=3,
                                    order_by=nodes.c.id),
            'data':deferred(nodes.c.data)
        })
        sess = create_session()
        n1 = Node(data='n1')
        n1.append(Node(data='n11'))
        n1.append(Node(data='n12'))
        sess.add(n1)
        sess.flush()
        sess.expunge_all()

        def go():
            eq_( 
                Node(data='n1', children=[Node(data='n11'), Node(data='n12')]),
                sess.query(Node).order_by(Node.id).first(),
                )
        self.assert_sql_count(testing.db, go, 6)

        sess.expunge_all()

        def go():
            eq_(Node(data='n1', children=[Node(data='n11'), Node(data='n12')]),
                sess.query(Node).options(undefer('data')).order_by(Node.id).first())
        self.assert_sql_count(testing.db, go, 5)

        sess.expunge_all()

        def go():
            eq_(Node(data='n1', children=[Node(data='n11'), Node(data='n12')]),
                sess.query(Node).options(undefer('data'),
                                            undefer('children.data')).first())
        self.assert_sql_count(testing.db, go, 3)


    @testing.resolve_artifact_names
    def test_options(self):
        class Node(_base.ComparableEntity):
            def append(self, node):
                self.children.append(node)

        mapper(Node, nodes, properties={
            'children':relationship(Node, order_by=nodes.c.id)
        }, order_by=nodes.c.id)
        sess = create_session()
        n1 = Node(data='n1')
        n1.append(Node(data='n11'))
        n1.append(Node(data='n12'))
        n1.append(Node(data='n13'))
        n1.children[1].append(Node(data='n121'))
        n1.children[1].append(Node(data='n122'))
        n1.children[1].append(Node(data='n123'))
        sess.add(n1)
        sess.flush()
        sess.expunge_all()
        def go():
            d = sess.query(Node).filter_by(data='n1').\
                        options(subqueryload_all('children.children')).first()
            eq_(Node(data='n1', children=[
                Node(data='n11'),
                Node(data='n12', children=[
                    Node(data='n121'),
                    Node(data='n122'),
                    Node(data='n123')
                ]),
                Node(data='n13')
            ]), d)
        self.assert_sql_count(testing.db, go, 3)

    @testing.fails_on('maxdb', 'FIXME: unknown')
    @testing.resolve_artifact_names
    def test_no_depth(self):
        """no join depth is set, so no eager loading occurs."""
        class Node(_base.ComparableEntity):
            def append(self, node):
                self.children.append(node)

        mapper(Node, nodes, properties={
            'children':relationship(Node, lazy='subquery')
        })
        sess = create_session()
        n1 = Node(data='n1')
        n1.append(Node(data='n11'))
        n1.append(Node(data='n12'))
        n1.append(Node(data='n13'))
        n1.children[1].append(Node(data='n121'))
        n1.children[1].append(Node(data='n122'))
        n1.children[1].append(Node(data='n123'))
        n2 = Node(data='n2')
        n2.append(Node(data='n21'))
        sess.add(n1)
        sess.add(n2)
        sess.flush()
        sess.expunge_all()
        def go():
            d = sess.query(Node).filter(Node.data.in_(['n1', 'n2'])).order_by(Node.data).all()
            eq_([
                Node(data='n1', children=[
                    Node(data='n11'),
                    Node(data='n12', children=[
                        Node(data='n121'),
                        Node(data='n122'),
                        Node(data='n123')
                    ]),
                    Node(data='n13')
                ]),
                Node(data='n2', children=[
                    Node(data='n21')
                ])
            ], d)
        self.assert_sql_count(testing.db, go, 4)