The example below raises an:
sqlalchemy.exceptions.AssertionError: Dependency rule tried to blank-
out primary key column 'userdata.user_id' on instance
'[EMAIL PROTECTED]'
The code creates 2 objects having a 1:1 relation with cascade-delete.
The ForeignKey is declared as a primary key. This seems to cause the
Error.
Versions: Python 2.4, SA 0.3.1, SA 0.3.4
class User(object):
pass
class Userdata(object):
def __init__(self, user):
self.user_id = user.id
if __name__=="__main__":
db = create_engine("mysql://[EMAIL PROTECTED]/test_cascade")
session = create_session()
metadata = BoundMetaData(db)
t_user = Table("user",metadata,
Column("id",Integer,primary_key=True),
)
t_userdata = Table("userdata",metadata,
Column("user_id",Integer,ForeignKey("user.id"),primary_key=True),
)
metadata.create_all()
mapper(User, t_user)
mapper(Userdata, t_userdata, properties = {
"myuser":relation(User,backref=backref("meta",cascade="delete"))
})
# create 1 instance of each object:
user1 = User()
session.save(user1)
session.flush()
data1 = Userdata(user1)
session.save(data1)
session.flush()
# now delete the user,
# expecting the cascade to delete userdata,too:
session.delete(user1)
session.flush() #AssertionError: Dependency rule tried to blank-
out ...
I can workaround this error by using a separate primary key in table
userdata:
t_userdata = Table("userdata",metadata,
Column("id",Integer,primary_key=True),
Column("user_id",Integer,ForeignKey("user.id")),
)
and everything works fine.
I'm wondering whether this is an SA bug, or a bad table design ?
Thanks and regards,
Ruben
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