Hi everybody!
I've got a schema with a combined 1:n:1 + m:n relation.
In detail, I have the entities "user" and "event" and the relation
"participation".
That leads to 1:n user->participation, n:1 participation->event, and
m:n user->event:
[user] 1 -- * [participation] * -- 1 [event]
* \_________________________________/ *
Now the (assumed) bug is that the participation mapping only works
correctly after saving, flushing, clearing and retrieving the objects
(output only included where relevant):
u = User(); u.name = "test user"
e = Event(); e.title = "test event"
u.events.append(e)
u.participations
[] #empty!
e.participations
[] #empty!
session.save(u); session.save(e); session.flush(); session.clear()
u = session.query(User).get(1)
e = session.query(Event).get(1)
[<__main__.Participation object at 0x01035F50>] # not empty!
e.participations
[<__main__.Participation object at 0x01035F50>] # not empty!
I think that the results should be identical before and after save/
flush/clear/query.
Is this assumption wrong?
Am I really supposed to save/flush/clear/query my objects to get the
correct mappings?
Or is this a bug?
The full code can be found below (tested with 0.4.0b6):
#=============================
from datetime import datetime
from sqlalchemy import MetaData, Table, Column, String, DateTime,
Integer, Boolean, Unicode, ForeignKey, and_, or_, create_engine
from sqlalchemy.orm import mapper, relation, sessionmaker
engine = create_engine('sqlite:///:memory:')
metadata = MetaData()
user_table = Table('user', metadata,
Column('user_id', Integer, primary_key=True),
Column('name', Unicode(255))
)
event_table = Table('event', metadata,
Column('event_id', Integer, primary_key=True),
Column('title', Unicode(255))
)
participation_table = Table('participation', metadata,
Column('event_id', Integer, ForeignKey('event.event_id',
onupdate="CASCADE", ondelete="CASCADE"), primary_key=True),
Column('user_id', Integer, ForeignKey('user.user_id',
onupdate="CASCADE", ondelete="CASCADE"), primary_key=True),
Column('status', Integer, nullable=False, default=0),
)
metadata.create_all(engine)
class User(object):
pass
class Event(object):
pass
class Participation(object):
pass
mapper(User, user_table,
properties=dict(
participations=relation(Participation, backref='user'),
)
)
mapper(Event, event_table,
properties=dict(
users=relation(User, secondary=participation_table,
backref='events'),
participations=relation(Participation, backref='event'),
)
)
mapper(Participation, participation_table)
Session = sessionmaker(bind=engine)
session = Session()
u = User()
u.name = "test user"
e = Event()
e.title = "test event"
u.events.append(e)
u.events
e.users
u.participations
e.participations
session.save(u)
session.save(e)
session.flush()
session.clear()
u = session.query(User).get(1)
e = session.query(Event).get(1)
u.participations
e.participations
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