On Jun 5, 3:57 pm, Michael Bayer <[EMAIL PROTECTED]> wrote:
> On Jun 5, 2007, at 6:39 AM, lingo wrote:
>
>
>
> > I'm using Sqlalchemy with PostgreSQL in a project.
>
> > Some of the relations (foreign keys) in the database (postgresql) have
> > ON_DELETE=RESTRICT which should prevent parent objects with existing
> > child objects from being deleted (tested, works in pg client).
>
> ON_DELETE=RESTRICT is the virtually the same as the default setting
> of "NO ACTION" in Postgres. SQLAlchemy's ORM organizes SQL
> operations according to foreign key dependency and no errors should
> occur.
First i stripped the primary joins from the relations (thanks, it
saves me a lot of code/work).
now it looks like:
Parent_table = sa.Table('Parent', metadata, autoload=True)
Child_table = sa.Table('Child', metadata, autoload=True)
orm.mapper(Parent,Parent_table, properties={
'Children' : relation(Child, cascade="save-update")
}
)
orm.mapper(Child,Child_table, properties={
'Parent' : relation(Parent, cascade="save-update")
}
)
I switched on debugging on sqlalchemy to see what happens when i try
to delete a "parent" object.
The weird thing is (and probably was also the case before) that the
parent gets deleted, and the child isn't. After parent-deletion the
foreign key on the child is set to null (or empty). This is not the
expected behavior when using "on delete=restrict", this is more like
"on delete=set null".
In the debug output i spotted some lines mentioning foreign keys, but
I'm not really sure what to look for.
Any hints?
>
>
> > An example of my current mappings:
> > Child_table = sa.Table('Child', metadata, autoload=True)
> > Parent_table = sa.Table('Parent', metadata, autoload=True)
>
> > orm.mapper(Parent,Parent_table, properties={
> > 'Children' :
> > relation(Child,primaryjoin=Parent_table.c.id==Child_table.c.parent_id,
> > backref=backref("Parent", remote_side=[Parent_table.c.id]))
> > }
> > )
>
> I notice you are specifying primary join conditions manually. these
> should pick up automatically based on the foreign keys present in
> child/parent table. is it possible that the foreign keys are not
> being detected in the autoload=True operation ? try spelling out the
> tables manually not using autoload=True.
setting autoload=False is not really an option for my project
(although i will try to test it to see if the foreign key constraints
will work that way).
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