On Jul 3, 2013, at 5:52 PM, Josh Kuhn <habi...@gmail.com> wrote:
>
> I still get an integrity error because the after_flush happens after I've
> already tried to insert the null gadgets. If I move the flush after the
> widget is added to the session, but before the gadgets are, then the
> query(Gadget).with_parent(widget) obviously won't find anything.
oh, well nullable=False. then you obviously can't rely on UPDATE here, you
need to get at those rows before they are inserted and after the Widget has
machine_id, so you need to use flush events to get at individual cases:
1. when gadget is inserted, needs machine_id (add "widget" backref):
@event.listens_for(Gadget, "before_insert")
def before_gadget(mapper, connection, target):
target.machine_id = target.widget.machine_id
2. when widget is updated, gadgets need new machine_id, here UPDATE is probably
best since the Gadget might not be part of the flush:
@event.listens_for(Widget, "after_update")
def after_widget(mapper, connection, target):
connection.execute(
Gadget.__table__.update().
values(machine_id=target.machine_id).
where(Gadget.widget_id == target.widget_id)
)
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