Hi all,
This is my first question regarding to SQLAlchemy, you can count me as a
newbie. Here is my problem:
I've this inheritance between my Python classes, everything were working
fine until last night when I've added another class to my inheritance
hierarchy. I've tried to find the cause of that pretty much read all the
documentation about session, but couldn't find any solution.
I'm going to try to reduce the things I'm writing here by not including all
the attributes/methods below, so warn me if you spot something:
This is the basic inheritance to let you figure out what is inheriting from
what:
class SimpleEntity(object):
pass
class Entity(SimpleEntity):
pass
class TypeEntity(Entity):
pass
class LinkType(TypeEntity):
pass
Here are the Tables (just the ones used with these classes, there are a lot
other tables too, I can paste them here if you ask for):
# SIMPLE ENTITY
simpleEntities = Table(
"simpleEntities", metadata,
Column("id", Integer, primary_key=True),
Column("name", String(256), nullable=False),
Column("description", String),
Column(
"created_by_id",
Integer,
ForeignKey("users.id", use_alter=True, name="x")
),
Column(
"updated_by_id",
Integer,
ForeignKey("users.id", use_alter=True, name="x")
),
Column("date_created", DateTime),
Column("date_updated", DateTime),
Column("entity_type", String(128), nullable=False),
UniqueConstraint('name', 'entity_type')
)
# ENTITY
entities = Table(
"entities", metadata,
Column(
"id",
ForeignKey("simpleEntities.id"),
primary_key=True
),
)
# TYPEENTITIES
typeEntities = Table(
"typeEntities", metadata,
Column(
"id",
Integer,
ForeignKey("entities.id"),
primary_key=True,
),
)
# LINKTYPES
linkTypes = Table(
"linkTypes", metadata,
Column(
"id",
Integer,
ForeignKey("typeEntities.id"),
),
)
Mappers:
# SimpleEntity
mapper(
entity.SimpleEntity,
tables.simpleEntities,
properties={
"_name": tables.simpleEntities.c.name,
"name": synonym("_name"),
"_description": tables.simpleEntities.c.description,
"description": synonym("_description"),
"_created_by": relationship(
user.User,
backref="_entities_created",
primaryjoin=tables.simpleEntities.c.created_by_id== \
tables.users.c.id,
post_update=True,
uselist=False
),
"created_by": synonym("_created_by"),
"_updated_by": relationship(
user.User,
backref="_entities_updated",
primaryjoin=tables.simpleEntities.c.updated_by_id== \
tables.users.c.id,
post_update=True,
uselist=False
),
"updated_by": synonym("_updated_by"),
"_date_created": tables.simpleEntities.c.date_created,
"date_created": synonym("_date_created"),
"_date_updated": tables.simpleEntities.c.date_updated,
"date_updated": synonym("_date_updated")
},
polymorphic_on=tables.simpleEntities.c.entity_type,
polymorphic_identity="SimpleEntity"
)
# Entity
mapper(
entity.Entity,
tables.entities,
inherits=entity.SimpleEntity,
inherit_condition=tables.entities.c.id==tables.simpleEntities.c.id,
polymorphic_identity="Entity",
properties={
"_tags": relationship(
tag.Tag,
secondary=tables.entity_tags,
backref="_entities"
),
"tags": synonym("_tags")
}
)
# TypeEntity
mapper(
entity.TypeEntity,
tables.typeEntities,
inherits=entity.Entity,
inherit_condition=tables.typeEntities.c.id==tables.entities.c.id,
polymorphic_identity="TypeEntity",
)
# LinkType
mapper(
types.LinkType,
tables.linkTypes,
inherits=entity.TypeEntity,
inherit_condition=tables.linkTypes.c.id==tables.typeEntities.c.id,
polymorphic_identity="LinkType",
)
Alright here it comes slowly, my session object is set up in another module
(like the classes, tables and mappers are all in seperate modules), but I'm
going to try to merge them here:
>>> engine = create_engine("sqlite:///:memory:", "echo":True)
here are calls for the mappers shown above:
>>> mappers.setup()
>>> create_all(engine)
>>> Session = sessionmaker(bind=engine)
>>> session = Session()
>>> sound_link_type = LinkType(name="Sound")
>>> sound_linkt_type.__dict__
{'_created_by': None, '_sa_instance_state':
<sqlalchemy.orm.state.InstanceState object at 0x19866d0>, '_description':
'', '_date_updated': datetime.datetime(2011, 1, 11, 15, 44, 27, 954088),
'_date_created': datetime.datetime(2011, 1, 11, 15, 44, 27, 954074),
'_tags': [], '_name': 'Sound', '_nice_name': 'sound', '_updated_by': None}
>>> session.add(sound_link_type)
>>> session.commit()
2011-01-11 15:46:23,955 INFO sqlalchemy.engine.base.Engine.0x...8f50 BEGIN
(implicit)
2011-01-11 15:46:23,956 INFO sqlalchemy.engine.base.Engine.0x...8f50 INSERT
INTO "simpleEntities" (name, description, created_by_id, updated_by_id,
date_created, date_updated, entity_type) VALUES (?, ?, ?, ?, ?, ?, ?)
2011-01-11 15:46:23,957 INFO sqlalchemy.engine.base.Engine.0x...8f50
('Sound', '', None, None, '2011-01-11 15:44:27.954074', '2011-01-11
15:44:27.954088', 'LinkType')
2011-01-11 15:46:23,960 INFO sqlalchemy.engine.base.Engine.0x...8f50 INSERT
INTO entities (id) VALUES (?)
2011-01-11 15:46:23,961 INFO sqlalchemy.engine.base.Engine.0x...8f50 (3,)
2011-01-11 15:46:23,962 INFO sqlalchemy.engine.base.Engine.0x...8f50 INSERT
INTO "typeEntities" (id) VALUES (?)
2011-01-11 15:46:23,962 INFO sqlalchemy.engine.base.Engine.0x...8f50 (3,)
2011-01-11 15:46:23,964 INFO sqlalchemy.engine.base.Engine.0x...8f50 COMMIT
>>> sound_link_type.__dict__
{'_sa_instance_state': <sqlalchemy.orm.state.InstanceState object at
0x19866d0>, '_nice_name': 'sound'}
>>> sound_link_type.name
2011-01-11 15:47:00,570 INFO sqlalchemy.engine.base.Engine.0x...8f50 BEGIN
(implicit)
2011-01-11 15:47:00,571 INFO sqlalchemy.engine.base.Engine.0x...8f50 SELECT
"simpleEntities".description AS "simpleEntities_description",
"simpleEntities".date_updated AS "simpleEntities_date_updated",
"simpleEntities".date_created AS "simpleEntities_date_created",
"simpleEntities".name AS "simpleEntities_name", "simpleEntities".id AS
"simpleEntities_id", entities.id AS entities_id, "typeEntities".id AS
"typeEntities_id", "linkTypes".id AS "linkTypes_id",
"simpleEntities".created_by_id AS "simpleEntities_created_by_id",
"simpleEntities".updated_by_id AS "simpleEntities_updated_by_id",
"simpleEntities".entity_type AS "simpleEntities_entity_type"
FROM "simpleEntities" JOIN entities ON entities.id = "simpleEntities".id
JOIN "typeEntities" ON "typeEntities".id = entities.id JOIN "linkTypes" ON
"linkTypes".id = "typeEntities".id
WHERE "simpleEntities".id = ?
2011-01-11 15:47:00,571 INFO sqlalchemy.engine.base.Engine.0x...8f50 (3,)
2011-01-11 15:47:00,832 INFO sqlalchemy.engine.base.Engine.0x...8f50 SELECT
"simpleEntities".description AS "simpleEntities_description",
"simpleEntities".date_updated AS "simpleEntities_date_updated",
"simpleEntities".date_created AS "simpleEntities_date_created",
"simpleEntities".name AS "simpleEntities_name", "simpleEntities".id AS
"simpleEntities_id", entities.id AS entities_id, "typeEntities".id AS
"typeEntities_id", "linkTypes".id AS "linkTypes_id",
"simpleEntities".created_by_id AS "simpleEntities_created_by_id",
"simpleEntities".updated_by_id AS "simpleEntities_updated_by_id",
"simpleEntities".entity_type AS "simpleEntities_entity_type"
FROM "simpleEntities" JOIN entities ON entities.id = "simpleEntities".id
JOIN "typeEntities" ON "typeEntities".id = entities.id JOIN "linkTypes" ON
"linkTypes".id = "typeEntities".id
WHERE "simpleEntities".id = ?
2011-01-11 15:47:00,832 INFO sqlalchemy.engine.base.Engine.0x...8f50 (3,)
sqlalchemy.orm.exc.ObjectDeletedError: Instance '<LinkType at 0x19865d0>'
has been deleted.
any idea ??? (also for the sake of brevity I didn't include the echoed lines
when I call create_all, I can send it too if it will help)
E.Ozgur Yilmaz
Lead Technical Director
eoyilmaz.blogspot.com
www.ozgurfx.com
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