On Jan 22, 2012, at 8:21 PM, Jackson, Cameron wrote: > So I figured out that I can do this: > try: > self.session.delete(row) > self.session.flush() > except sqlalchemy.exc.IntegrityError: > print "Can't do that!" > > But that really isn't a lot of help, because I'm now stuck with a useless > transaction. If the user makes a bunch of changes, then tries to delete > something that's still being referenced elsewhere, I have to rollback() > *everything* they've done so far. Not good. > > So I either need a way to rollback *just* the dodgy deletion, or a way to > anticipate the IntegrityError and not do the deletion at all. The latter > would be better, but I'm OK with either..
how would you guard against a "useless transaction" assuming normal ORM usage with queries and all of that in any case ? the transaction starts as soon as they look at the database in any way. anyway, there's no way to know if the DB has rows that point to a target row without querying the database at some point, so not sure what you want to do there. -- 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.
