Ah, I should say I'm using SA 0.4.3 - I going to try the same test on
0.5
On Dec 5, 11:36 am, Michael Bayer <[EMAIL PROTECTED]> wrote:
> actually, use passive_deletes=True, not 'all'. It will issue DELETEs
> only for collections that are already loaded, this doesn't break
> anything and prevents unnecessary SELECTs of unloaded collections.
> The True setting is needed so that the session can update the state of
> those collections during the flush process.
>
> On Dec 5, 2008, at 12:29 PM, Michael Bayer wrote:
>
> > use the "passive_updates=True, passive_deletes='all'" flags. These
> > are described
> > athttp://www.sqlalchemy.org/docs/05/sqlalchemy_orm.html#docstrings_sqla...
> > .
>
> > On Dec 5, 2008, at 11:42 AM, James Brady wrote:
>
> >> Hi all,
> >> I'm trying to get deletes and updates cascaded down from a parent
> >> object to the child objects (connected by ForeignKey).
>
> >> It all seems pretty simple in the docs, but I can't get it to work!
> >> I'm using MySQL with the InnoDB engine, and have played with all
> >> the variation of the onupdate, ondelete and cascade arguments I can
> >> think of.
>
> >> The problem is that immediately before the DELETE command is sent
> >> to MySQL, there are UPDATE commands nulling out the foreign key
> >> references of the child objects, so MySQL doesn't trigger it's ON
> >> DELETE CASCADE action, and for some reason cascade="all, delete-
> >> orphan" doesn't clean up the children with NULL FKs.
>
> >> Here's a simplified model:
> >> users_table = Table('tg_user', metadata,
> >> Column('user_id', Integer, primary_key=True),
> >> Column('created', DateTime, default=datetime.now),
> >> mysql_engine='InnoDB',
> >> )
>
> >> hat_table = Table('hat', metadata,
> >> Column('id', Integer, primary_key=True),
> >> Column('name', Unicode(100)),
> >> Column('user_id', Integer, ForeignKey('tg_user.user_id'),
> >> onupdate='CASCADE', ondelete='CASCADE'),
> >> mysql_engine='InnoDB',
> >> )
>
> >> class User(object):
> >> pass
>
> >> class Hat(object):
> >> pass
>
> >> mapper(User, users_table)
>
> >> mapper(Hat, hat_table,
> >> properties = {
> >> 'user': relation(User, backref="hats", cascade="all,
> >> delete, delete-orphan"),
> >> }
> >> )
>
> >> And the log from SA when I do a User.delete:
> >> BEGIN
> >> UPDATE hat SET user_id=%s WHERE hat.id = %s
> >> [None, 1L]
> >> DELETE FROM tg_user WHERE tg_user.user_id = %s
> >> [1L]
> >> COMMIT
>
> >> Any help would be much appreciated!
>
> >> James
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