On Mar 21, 2012, at 5:18 AM, Pau Tallada wrote: > Hi! > > I have a model with a parent-child relationship on the same entity. > The "children" collection on a parent instance has events set to intercept > adding and removing instances to/from it. This is needed to update an > attribute from the parent instance. > But when I delete an instance which is the child of another one, that parent > instance is not notified of its child removal and so the event is not fired. > > I tried working with the cascade rules but I have not been successful. > > Is this behaviour supported?
"delete an instance", meaning, parent.children.append(child) session.delete(child) session.commit() ? in that case no, "parent.children" is not notified of a collection removal, since no collection alteration actually takes place. The "child" is still there in parent.collection until the whole of "parent" is expired, which occurs after the commit(). See http://docs.sqlalchemy.org/en/latest/orm/session.html#deleting-from-collections for detailed discussion on this. Your two options here are to stick to collection mutations, or do an additional before_flush() or after_flush() event that goes through child objects marked deleted, finds their parents, and does what is needed. > > Thanks! > > Pau. > -- > ---------------------------------- > Pau Tallada Crespí > Dep. d'Astrofísica i Cosmologia > Port d'Informació Científica (PIC) > Tel: +34 93 586 8233 > ---------------------------------- > > > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalchemy@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
