[storm] Deletion questions

[Morten Siebuhr]

Hi,

I've hit some problems when deleting (i.e. store.remove()) objects from
the store and reference integrity (only applies to PostgreSQL - all
other tested engines does not fail on this).

My application maintains a list of users, their computers, NICs, where
the computers have a foreign key to the owners' userid and the NICs have
one for the computer they're in.

When I remove a user from the system, I build a list of objects to
delete, i.e.:

delete = [user]

for computer in user.computers:
    delete.append(computer)
    for interface in computer.interfaces:
        delete.append(interface)

if not ask_user("Do you want to delete %d items?" % (len(delete)):
    return

delete.reverse()
for del_item in delete:
    storm.remove(del_item)
storm.commit()

When I get to the commit, it usually fails with a integrity/foreign key
error, as the objects are flushed in a different order than I call
delete on them.

What is the best way to get around this? Call store.flush() after each
store.remove(xx), or store.add_flush_order(last_xx, xx) for each item,
or something completely different? How will Storm react if I use
cascading deletes?

Regards,
/Morten Siebuhr