Hi, I have data model with joined table inheritance + relations between classes of this joined table inheritance class hierarchy. This works well with sqlalchemy 0.5.2, but when upgrading to 0.5.4p2, i get the following exception:
sqlalchemy.exc.ArgumentError: Entity.creator and back-reference
Client.entities_created are both of the same direction <symbol 'ONETOMANY>.
Did you mean to set remote_side on the many-to-one side?
Here is a sample test case showing my problem:
First the class hierarchy schema:
[image: schema.png]
so Client inherits from Entity, and Entity and Client have a one to many
relation (each Entity is "created" by a Client)
then the code:
import sqlalchemy, sqlalchemy.orm
from sqlalchemy import Table, Column, Sequence, Integer, Text, Boolean,
DateTime, ForeignKey
from sqlalchemy.orm import mapper, relation
class EntityType(object):
Entity = 0
Client = 1
class Entity(object):
pass
class Client(Entity):
pass
engine = sqlalchemy.create_engine('sqlite:///:memory:', echo=True)
connexion = engine.connect()
metadata = sqlalchemy.MetaData()
metadata.bind = engine
session_maker = sqlalchemy.orm.sessionmaker(bind = engine, autoflush = True,
autocommit = False)
session = session_maker()
entity_table = Table(
'entity', metadata,
Column('id', Text, primary_key = True),
Column('entity_type', Integer, nullable = False, index = True),
Column('id_creator', Text, ForeignKey('entity.id'), nullable = False,
index = True),
Column('description', Text))
client_table = Table(
'client_data', metadata,
Column('id', Text, ForeignKey('entity.id'), primary_key = True),
Column('data', Text))
metadata.create_all()
connexion.execute(entity_table.insert(), [{
'id': 'root',
'id_creator': 'root',
'entity_type': EntityType.Client,
'description': 'Lorem ipsum' }])
connexion.execute(client_table.insert(), [{
'id': 'root',
'data': 'dolor sit amet'}])
mapper(Entity,
entity_table,
polymorphic_on = entity_table.c.entity_type,
polymorphic_identity = EntityType.Entity,
properties = {
'creator':
relation(Client,
collection_class = set,
primaryjoin = entity_table.c.id_creator ==
entity_table.c.id,
foreign_keys = [entity_table.c.id_creator],
backref = sqlalchemy.orm.backref('entities_created',
foreign_keys = [entity_table.c.id]))})
mapper(Client,
client_table,
inherits = Entity,
polymorphic_identity = EntityType.Client)
root = session.query(Client).get('root')
when running on 0.5.2, everything is ok.
when running on 0.5.4 i get the following stack trace:
Traceback (most recent call last):
File "test.py", line 63, in <module>
root = session.query(Client).get('root')
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/session.py", line 895,
in query
return self._query_cls(entities, self, **kwargs)
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/query.py", line 91, in
__init__
self._set_entities(entities)
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/query.py", line 100, in
_set_entities
self.__setup_aliasizers(self._entities)
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/query.py", line 114, in
__setup_aliasizers
mapper, selectable, is_aliased_class = _entity_info(entity)
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/util.py", line 492, in
_entity_info
mapper = class_mapper(entity, compile)
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/util.py", line 567, in
class_mapper
mapper = mapper.compile()
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/mapper.py", line 658, in
compile
mapper._post_configure_properties()
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/mapper.py", line 687, in
_post_configure_properties
prop.init()
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/interfaces.py", line
408, in init
self.do_init()
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/properties.py", line
717, in do_init
self._post_init()
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/properties.py", line
1015, in _post_init
self.backref.compile(self)
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/properties.py", line
1174, in compile
prop._add_reverse_property(self.key)
File "/usr/lib/pymodules/python2.5/sqlalchemy/orm/properties.py", line
708, in _add_reverse_property
" Did you mean to set remote_side on the many-to-one side ?" % (self,
other, self.direction))
sqlalchemy.exc.ArgumentError: Entity.creator and back-reference
Client.entities_created are both of the same direction <symbol 'ONETOMANY>.
Did you mean to set remote_side on the many-to-one side ?
I looked at other mails mentionning this exception (notably:
http://groups.google.com/group/sqlalchemy/browse_thread/thread/232305afeab6ea18/6d10fe9712b3fdef?lnk=gst&q=both+of+the+same+direction#6d10fe9712b3fdefand
http://groups.google.com/group/sqlalchemy/browse_thread/thread/d183b378c38448bf/0d96e44d92d7a45d?lnk=gst&q=both+of+the+same+direction#0d96e44d92d7a45d)
so i added the explicit foreign_keys declaration in the backref
'entities_created', but the problem is still there.
any help appreciated [?]
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<<inline: schema.png>>
<<inline: 330.gif>>
