"""
Primary key changing capabilities and passive/non-passive cascading updates.

"""
from sqlalchemy.test.testing import eq_, assert_raises, assert_raises_message
import sqlalchemy as sa
from sqlalchemy.test import testing
from sqlalchemy import Integer, String, ForeignKey
from sqlalchemy.test.schema import Table, Column
from sqlalchemy.orm import mapper, relation, create_session
from sqlalchemy.test.testing import eq_
from test.orm import _base

class NaturalPKTest(_base.MappedTest):

    @classmethod
    def define_tables(cls, metadata):
        if testing.against('oracle'):
            fk_args = dict(deferrable=True, initially='deferred')
        else:
            fk_args = dict(onupdate='cascade')
            
        users = Table('users', metadata,
            Column('username', String(50), primary_key=True),
            Column('fullname', String(100)),
            test_needs_fk=True)

        addresses = Table('addresses', metadata,
            Column('email', String(50), primary_key=True),
            Column('username', String(50), ForeignKey('users.username', **fk_args)),
            test_needs_fk=True)

        items = Table('items', metadata,
            Column('itemname', String(50), primary_key=True),
            Column('description', String(100)), 
            test_needs_fk=True)

        users_to_items = Table('users_to_items', metadata,
            Column('username', String(50), ForeignKey('users.username', **fk_args), primary_key=True),
            Column('itemname', String(50), ForeignKey('items.itemname', **fk_args), primary_key=True),
            test_needs_fk=True)

    @classmethod
    def setup_classes(cls):
        class User(_base.ComparableEntity):
            pass
        class Address(_base.ComparableEntity):
            pass
        class Item(_base.ComparableEntity):
            pass

    @testing.resolve_artifact_names
    def test_entity(self):
        mapper(User, users)

        sess = create_session()
        u1 = User(username='jack', fullname='jack')

        sess.add(u1)
        sess.flush()
        assert sess.query(User).get('jack') is u1

        u1.username = 'ed'
        sess.flush()

        def go():
            assert sess.query(User).get('ed') is u1
        self.assert_sql_count(testing.db, go, 0)

        assert sess.query(User).get('jack') is None

        sess.expunge_all()
        u1 = sess.query(User).get('ed')
        eq_(User(username='ed', fullname='jack'), u1)

    @testing.resolve_artifact_names
    def test_load_after_expire(self):
        mapper(User, users)

        sess = create_session()
        u1 = User(username='jack', fullname='jack')

        sess.add(u1)
        sess.flush()
        assert sess.query(User).get('jack') is u1

        users.update(values={User.username:'jack'}).execute(username='ed')

        # expire/refresh works off of primary key.  the PK is gone
        # in this case so theres no way to look it up.  criterion-
        # based session invalidation could solve this [ticket:911]
        sess.expire(u1)
        assert_raises(sa.orm.exc.ObjectDeletedError, getattr, u1, 'username')

        sess.expunge_all()
        assert sess.query(User).get('jack') is None
        assert sess.query(User).get('ed').fullname == 'jack'

    @testing.resolve_artifact_names
    def test_flush_new_pk_after_expire(self):
        mapper(User, users)
        sess = create_session()
        u1 = User(username='jack', fullname='jack')

        sess.add(u1)
        sess.flush()
        assert sess.query(User).get('jack') is u1

        sess.expire(u1)
        u1.username = 'ed'
        sess.flush()
        sess.expunge_all()
        assert sess.query(User).get('ed').fullname == 'jack'
        

    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_onetomany_passive(self):
        self._test_onetomany(True)

    def test_onetomany_nonpassive(self):
        self._test_onetomany(False)

    @testing.resolve_artifact_names
    def _test_onetomany(self, passive_updates):
        mapper(User, users, properties={
            'addresses':relation(Address, passive_updates=passive_updates)
        })
        mapper(Address, addresses)

        sess = create_session()
        u1 = User(username='jack', fullname='jack')
        u1.addresses.append(Address(email='jack1'))
        u1.addresses.append(Address(email='jack2'))
        sess.add(u1)
        sess.flush()

        assert sess.query(Address).get('jack1') is u1.addresses[0]

        u1.username = 'ed'
        sess.flush()
        assert u1.addresses[0].username == 'ed'

        sess.expunge_all()
        eq_([Address(username='ed'), Address(username='ed')], sess.query(Address).all())

        u1 = sess.query(User).get('ed')
        u1.username = 'jack'
        def go():
            sess.flush()
        if not passive_updates:
            self.assert_sql_count(testing.db, go, 4) # test passive_updates=False; load addresses, update user, update 2 addresses
        else:
            self.assert_sql_count(testing.db, go, 1) # test passive_updates=True; update user
        sess.expunge_all()
        assert User(username='jack', addresses=[Address(username='jack'), Address(username='jack')]) == sess.query(User).get('jack')

        u1 = sess.query(User).get('jack')
        u1.addresses = []
        u1.username = 'fred'
        sess.flush()
        sess.expunge_all()
        assert sess.query(Address).get('jack1').username is None
        u1 = sess.query(User).get('fred')
        eq_(User(username='fred', fullname='jack'), u1)
        

    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_manytoone_passive(self):
        self._test_manytoone(True)

    def test_manytoone_nonpassive(self):
        self._test_manytoone(False)

    @testing.resolve_artifact_names
    def _test_manytoone(self, passive_updates):
        mapper(User, users)
        mapper(Address, addresses, properties={
            'user':relation(User, passive_updates=passive_updates)
        })

        sess = create_session()
        a1 = Address(email='jack1')
        a2 = Address(email='jack2')

        u1 = User(username='jack', fullname='jack')
        a1.user = u1
        a2.user = u1
        sess.add(a1)
        sess.add(a2)
        sess.flush()

        u1.username = 'ed'

        def go():
            sess.flush()
        if passive_updates:
            self.assert_sql_count(testing.db, go, 1)
        else:
            self.assert_sql_count(testing.db, go, 3)

        def go():
            sess.flush()
        self.assert_sql_count(testing.db, go, 0)

        assert a1.username == a2.username == 'ed'
        sess.expunge_all()
        eq_([Address(username='ed'), Address(username='ed')], sess.query(Address).all())

    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_onetoone_passive(self):
        self._test_onetoone(True)

    def test_onetoone_nonpassive(self):
        self._test_onetoone(False)

    @testing.resolve_artifact_names
    def _test_onetoone(self, passive_updates):
        mapper(User, users, properties={
            "address":relation(Address, passive_updates=passive_updates, uselist=False)
        })
        mapper(Address, addresses)

        sess = create_session()
        u1 = User(username='jack', fullname='jack')
        sess.add(u1)
        sess.flush()
        
        a1 = Address(email='jack1')
        u1.address = a1
        sess.add(a1)
        sess.flush()

        u1.username = 'ed'

        def go():
            sess.flush()
        if passive_updates:
            sess.expire(u1, ['address'])
            self.assert_sql_count(testing.db, go, 1)
        else:
            self.assert_sql_count(testing.db, go, 2)

        def go():
            sess.flush()
        self.assert_sql_count(testing.db, go, 0)

        sess.expunge_all()
        eq_([Address(username='ed')], sess.query(Address).all())
        
    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_bidirectional_passive(self):
        self._test_bidirectional(True)

    def test_bidirectional_nonpassive(self):
        self._test_bidirectional(False)

    @testing.resolve_artifact_names
    def _test_bidirectional(self, passive_updates):
        mapper(User, users)
        mapper(Address, addresses, properties={
            'user':relation(User, passive_updates=passive_updates,
                            backref='addresses')})

        sess = create_session()
        a1 = Address(email='jack1')
        a2 = Address(email='jack2')

        u1 = User(username='jack', fullname='jack')
        a1.user = u1
        a2.user = u1
        sess.add(a1)
        sess.add(a2)
        sess.flush()

        u1.username = 'ed'
        (ad1, ad2) = sess.query(Address).all()
        eq_([Address(username='jack'), Address(username='jack')], [ad1, ad2])
        def go():
            sess.flush()
        if passive_updates:
            sess.expire(u1, ['addresses'])
            self.assert_sql_count(testing.db, go, 1)
        else:
            self.assert_sql_count(testing.db, go, 3)
        eq_([Address(username='ed'), Address(username='ed')], [ad1, ad2])
        sess.expunge_all()
        eq_([Address(username='ed'), Address(username='ed')], sess.query(Address).all())

        u1 = sess.query(User).get('ed')
        assert len(u1.addresses) == 2    # load addresses
        u1.username = 'fred'
        def go():
            sess.flush()
        # check that the passive_updates is on on the other side
        if passive_updates:
            sess.expire(u1, ['addresses'])
            self.assert_sql_count(testing.db, go, 1)
        else:
            self.assert_sql_count(testing.db, go, 3)
        sess.expunge_all()
        eq_([Address(username='fred'), Address(username='fred')], sess.query(Address).all())


    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_manytomany_passive(self):
        self._test_manytomany(True)

    # mysqldb executemany() of the association table fails to report the correct row count
    @testing.fails_if(lambda: testing.against('mysql') and not testing.against('+zxjdbc'))
    def test_manytomany_nonpassive(self):
        self._test_manytomany(False)

    @testing.resolve_artifact_names
    def _test_manytomany(self, passive_updates):
        mapper(User, users, properties={
            'items':relation(Item, secondary=users_to_items, backref='users',
                             passive_updates=passive_updates)})
        mapper(Item, items)

        sess = create_session()
        u1 = User(username='jack')
        u2 = User(username='fred')
        i1 = Item(itemname='item1')
        i2 = Item(itemname='item2')

        u1.items.append(i1)
        u1.items.append(i2)
        i2.users.append(u2)
        sess.add(u1)
        sess.add(u2)
        sess.flush()

        r = sess.query(Item).all()
        # ComparableEntity can't handle a comparison with the backrefs
        # involved....
        eq_(Item(itemname='item1'), r[0])
        eq_(['jack'], [u.username for u in r[0].users])
        eq_(Item(itemname='item2'), r[1])
        eq_(['jack', 'fred'], [u.username for u in r[1].users])

        u2.username='ed'
        def go():
            sess.flush()
        go()
        def go():
            sess.flush()
        self.assert_sql_count(testing.db, go, 0)

        sess.expunge_all()
        r = sess.query(Item).all()
        eq_(Item(itemname='item1'), r[0])
        eq_(['jack'], [u.username for u in r[0].users])
        eq_(Item(itemname='item2'), r[1])
        eq_(['ed', 'jack'], sorted([u.username for u in r[1].users]))
        
        sess.expunge_all()
        u2 = sess.query(User).get(u2.username)
        u2.username='wendy'
        sess.flush()
        r = sess.query(Item).with_parent(u2).all()
        eq_(Item(itemname='item2'), r[0])

class ReversePKsTest(_base.MappedTest):
    """reverse the primary keys of two entities and ensure bookkeeping succeeds."""
    
    
    @classmethod
    def define_tables(cls, metadata):
        Table(
            'user', metadata,
            Column('code', Integer, primary_key=True),
            Column('status', Integer, primary_key=True),
            Column('username', String(50), nullable=False),
            )
    
    @classmethod
    def setup_classes(cls):
        class User(_base.ComparableEntity):
            def __init__(self, code, status, username):
                self.code = code
                self.status = status
                self.username = username

    @testing.resolve_artifact_names
    def test_reverse(self):
        PUBLISHED, EDITABLE, ARCHIVED = 1, 2, 3
        
        mapper(User, user)

        session = sa.orm.sessionmaker()()
        
        a_published = User(1, PUBLISHED, u'a')
        session.add(a_published)
        session.commit()

        a_editable = User(1, EDITABLE, u'a')

        session.add(a_editable)
        session.commit()

        # do the switch in both directions - 
        # one or the other should raise the error
        # based on platform dictionary ordering
        a_published.status = ARCHIVED
        a_editable.status = PUBLISHED

        session.commit()
        assert session.query(User).get([1, PUBLISHED]) is a_editable
        assert session.query(User).get([1, ARCHIVED]) is a_published

        a_published.status = PUBLISHED
        a_editable.status = EDITABLE

        session.commit()

        assert session.query(User).get([1, PUBLISHED]) is a_published
        assert session.query(User).get([1, EDITABLE]) is a_editable

    
class SelfRefTest(_base.MappedTest):
    __unsupported_on__ = 'mssql' # mssql doesn't allow ON UPDATE on self-referential keys

    @classmethod
    def define_tables(cls, metadata):
        if testing.against('oracle'):
            fk_args = dict(deferrable=True, initially='deferred')
        else:
            fk_args = dict(onupdate='cascade')
        
        Table('nodes', metadata,
              Column('name', String(50), primary_key=True),
              Column('parent', String(50),
                     ForeignKey('nodes.name', **fk_args)))

    @classmethod
    def setup_classes(cls):
        class Node(_base.ComparableEntity):
            pass

    @testing.resolve_artifact_names
    def test_onetomany(self):
        mapper(Node, nodes, properties={
            'children': relation(Node,
                                 backref=sa.orm.backref('parentnode',
                                                        remote_side=nodes.c.name,
                                                        passive_updates=False),
                                 passive_updates=False)})

        sess = create_session()
        n1 = Node(name='n1')
        n1.children.append(Node(name='n11'))
        n1.children.append(Node(name='n12'))
        n1.children.append(Node(name='n13'))
        sess.add(n1)
        sess.flush()

        n1.name = 'new n1'
        sess.flush()
        eq_(n1.children[1].parent, 'new n1')
        eq_(['new n1', 'new n1', 'new n1'],
            [n.parent
             for n in sess.query(Node).filter(
                 Node.name.in_(['n11', 'n12', 'n13']))])


class NonPKCascadeTest(_base.MappedTest):
    @classmethod
    def define_tables(cls, metadata):
        if testing.against('oracle'):
            fk_args = dict(deferrable=True, initially='deferred')
        else:
            fk_args = dict(onupdate='cascade')

        Table('users', metadata,
            Column('id', Integer, primary_key=True, test_needs_autoincrement=True),
            Column('username', String(50), unique=True),
            Column('fullname', String(100)),
            test_needs_fk=True)

        Table('addresses', metadata,
              Column('id', Integer, primary_key=True, test_needs_autoincrement=True),
              Column('email', String(50)),
              Column('username', String(50),
                     ForeignKey('users.username', **fk_args)),
                     test_needs_fk=True
                     )

    @classmethod
    def setup_classes(cls):
        class User(_base.ComparableEntity):
            pass
        class Address(_base.ComparableEntity):
            pass

    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_onetomany_passive(self):
        self._test_onetomany(True)

    def test_onetomany_nonpassive(self):
        self._test_onetomany(False)

    @testing.resolve_artifact_names
    def _test_onetomany(self, passive_updates):
        mapper(User, users, properties={
            'addresses':relation(Address, passive_updates=passive_updates)})
        mapper(Address, addresses)

        sess = create_session()
        u1 = User(username='jack', fullname='jack')
        u1.addresses.append(Address(email='jack1'))
        u1.addresses.append(Address(email='jack2'))
        sess.add(u1)
        sess.flush()
        a1 = u1.addresses[0]

        eq_(sa.select([addresses.c.username]).execute().fetchall(), [('jack',), ('jack',)])

        assert sess.query(Address).get(a1.id) is u1.addresses[0]

        u1.username = 'ed'
        sess.flush()
        assert u1.addresses[0].username == 'ed'
        eq_(sa.select([addresses.c.username]).execute().fetchall(), [('ed',), ('ed',)])

        sess.expunge_all()
        eq_([Address(username='ed'), Address(username='ed')], sess.query(Address).all())

        u1 = sess.query(User).get(u1.id)
        u1.username = 'jack'
        def go():
            sess.flush()
        if not passive_updates:
            self.assert_sql_count(testing.db, go, 4) # test passive_updates=False; load addresses, update user, update 2 addresses
        else:
            self.assert_sql_count(testing.db, go, 1) # test passive_updates=True; update user
        sess.expunge_all()
        assert User(username='jack', addresses=[Address(username='jack'), Address(username='jack')]) == sess.query(User).get(u1.id)
        sess.expunge_all()

        u1 = sess.query(User).get(u1.id)
        u1.addresses = []
        u1.username = 'fred'
        sess.flush()
        sess.expunge_all()
        a1 = sess.query(Address).get(a1.id)
        eq_(a1.username, None)

        eq_(sa.select([addresses.c.username]).execute().fetchall(), [(None,), (None,)])

        u1 = sess.query(User).get(u1.id)
        eq_(User(username='fred', fullname='jack'), u1)


class CascadeToFKPKTest(_base.MappedTest, testing.AssertsCompiledSQL):
    """A primary key mutation cascades onto a foreign key that is itself a primary key."""
    
    @classmethod
    def define_tables(cls, metadata):
        if testing.against('oracle'):
            fk_args = dict(deferrable=True, initially='deferred')
        else:
            fk_args = dict(onupdate='cascade')

        Table('users', metadata,
            Column('username', String(50), primary_key=True),
            test_needs_fk=True)

        Table('addresses', metadata,
                Column('username', String(50), 
                       ForeignKey('users.username', **fk_args),
                       primary_key=True
                       ),
              Column('email', String(50), primary_key=True),
              Column('etc', String(50)),
                 test_needs_fk=True
                 )

    @classmethod
    def setup_classes(cls):
        class User(_base.ComparableEntity):
            pass
        class Address(_base.ComparableEntity):
            pass
    
    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_onetomany_passive(self):
        self._test_onetomany(True)

    # PG etc. need passive=True to allow PK->PK cascade
    @testing.fails_on_everything_except('sqlite')
    def test_onetomany_nonpassive(self):
        self._test_onetomany(False)
        
    def test_move_passive(self):
        self._test_move(True)
        
    def test_move_nonpassive(self):
        self._test_move(False)

    @testing.resolve_artifact_names
    def _test_move(self, passive_updates):
        """Change the PK of a related entity to another.
        
        "on update cascade" is not involved here, so the mapper has 
        to do the UPDATE itself.
        
        """
        mapper(User, users, properties={
            'addresses':relation(Address, passive_updates=passive_updates)})
        mapper(Address, addresses)

        sess = create_session()
        a1 = Address(username='ed', email='ed@host1')
        u1 = User(username='ed', addresses=[a1])
        u2 = User(username='jack')
        
        sess.add_all([a1, u1, u2])
        sess.flush()
        
        a1.username = 'jack'
        sess.flush()
        
    @testing.resolve_artifact_names
    def test_rowswitch_doesntfire(self):
        mapper(User, users)
        mapper(Address, addresses, properties={
            'user':relation(User, passive_updates=True)
        })

        sess = create_session()
        u1 = User(username='ed')
        a1 = Address(user=u1, email='ed@host1')
        
        sess.add(u1)
        sess.add(a1)
        sess.flush()
        
        sess.delete(u1)
        sess.delete(a1)

        u2 = User(username='ed')
        a2 = Address(user=u2, email='ed@host1', etc='foo')
        sess.add(u2)
        sess.add(a2)

        from sqlalchemy.test.assertsql import CompiledSQL
        
        # test that the primary key columns of addresses are not
        # being updated as well, since this is a row switch.
        self.assert_sql_execution(testing.db,
                        sess.flush,
                        CompiledSQL("UPDATE addresses SET etc=:etc WHERE "
                                        "addresses.username = :addresses_username AND"
                                        " addresses.email = :addresses_email",
                         {'etc': 'foo', 'addresses_username':'ed', 'addresses_email':'ed@host1'} ),
                    )
        
        
    @testing.resolve_artifact_names
    def _test_onetomany(self, passive_updates):
        """Change the PK of a related entity via foreign key cascade.
        
        For databases that require "on update cascade", the mapper 
        has to identify the row by the new value, not the old, when
        it does the update.
        
        """
        mapper(User, users, properties={
            'addresses':relation(Address, passive_updates=passive_updates)})
        mapper(Address, addresses)
    
        sess = create_session()
        a1, a2 = Address(username='ed', email='ed@host1'), Address(username='ed', email='ed@host2')
        u1 = User(username='ed', addresses=[a1, a2])
        sess.add(u1)
        sess.flush()
        eq_(a1.username, 'ed')
        eq_(a2.username, 'ed')
        eq_(sa.select([addresses.c.username]).execute().fetchall(), [('ed',), ('ed',)])
        
        u1.username = 'jack'
        a2.email='ed@host3'
        sess.flush()

        eq_(a1.username, 'jack')
        eq_(a2.username, 'jack')
        eq_(sa.select([addresses.c.username]).execute().fetchall(), [('jack',), ('jack', )])


class JoinedInheritanceTest(_base.MappedTest):
    """Test cascades of pk->pk/fk on joined table inh."""

    @classmethod
    def define_tables(cls, metadata):
        if testing.against('oracle'):
            fk_args = dict(deferrable=True, initially='deferred')
        else:
            fk_args = dict(onupdate='cascade')

        Table('person', metadata,
            Column('name', String(50), primary_key=True),
            Column('type', String(50), nullable=False),
            test_needs_fk=True)
        
        Table('engineer', metadata,
            Column('name', String(50), ForeignKey('person.name', **fk_args), primary_key=True),
            Column('primary_language', String(50)),
            Column('boss_name', String(50), ForeignKey('manager.name', **fk_args)),
            test_needs_fk=True
        )

        Table('manager', metadata,
            Column('name', String(50), ForeignKey('person.name', **fk_args), primary_key=True),
            Column('paperwork', String(50)),
            test_needs_fk=True
        )

    @classmethod
    def setup_classes(cls):
        class Person(_base.ComparableEntity):
            pass
        class Engineer(Person):
            pass
        class Manager(Person):
            pass

    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_pk_passive(self):
        self._test_pk(True)

    # PG etc. need passive=True to allow PK->PK cascade
    @testing.fails_on_everything_except('sqlite')
    def test_pk_nonpassive(self):
        self._test_pk(False)
        
    @testing.fails_on('sqlite', 'sqlite doesnt support ON UPDATE CASCADE')
    @testing.fails_on('oracle', 'oracle doesnt support ON UPDATE CASCADE')
    def test_fk_passive(self):
        self._test_fk(True)
        
    # PG etc. need passive=True to allow PK->PK cascade
    @testing.fails_on_everything_except('sqlite')
    def test_fk_nonpassive(self):
        self._test_fk(False)

    @testing.resolve_artifact_names
    def _test_pk(self, passive_updates):
        mapper(Person, person, polymorphic_on=person.c.type, 
                polymorphic_identity='person', passive_updates=passive_updates)
        mapper(Engineer, engineer, inherits=Person, polymorphic_identity='engineer', properties={
            'boss':relation(Manager, 
                        primaryjoin=manager.c.name==engineer.c.boss_name,
                        passive_updates=passive_updates
                        )
        })
        mapper(Manager, manager, inherits=Person, polymorphic_identity='manager')

        sess = sa.orm.sessionmaker()()

        e1 = Engineer(name='dilbert', primary_language='java')
        sess.add(e1)
        sess.commit()
        e1.name = 'wally'
        e1.primary_language = 'c++'
        sess.commit()
        
    @testing.resolve_artifact_names
    def _test_fk(self, passive_updates):
        mapper(Person, person, polymorphic_on=person.c.type, 
                polymorphic_identity='person', passive_updates=passive_updates)
        mapper(Engineer, engineer, inherits=Person, polymorphic_identity='engineer', properties={
            'boss':relation(Manager, 
                        primaryjoin=manager.c.name==engineer.c.boss_name,
                        passive_updates=passive_updates
                        )
        })
        mapper(Manager, manager, inherits=Person, polymorphic_identity='manager')
        
        sess = sa.orm.sessionmaker()()
        
        m1 = Manager(name='dogbert', paperwork='lots')
        e1, e2 = \
                Engineer(name='dilbert', primary_language='java', boss=m1),\
                Engineer(name='wally', primary_language='c++', boss=m1)
        sess.add_all([
            e1, e2, m1
        ])
        sess.commit()
        
        m1.name = 'pointy haired'
        e1.primary_language = 'scala'
        e2.primary_language = 'cobol'
        sess.commit()
        
    
    
    
    