On Jul 14, 2008, at 7:19 PM, Jon wrote:
> I've encountered some weird stuff. I'm probably doing it wrong, but I > don't understand *why*. > > The following code: > > > s = Session() > # returns all accounts, the .licenses param > # not taken into consideration > accts = s.query(Account).filter(Account.licenses==[]) > print accts > print > > accts = s.query(Account).filter(Account.licenses.any()) > print accts > print > > # returns the correct list of accounts. > accts = s.query(Account).filter(Account.licenses==None) > print accts > print > > print accts[0].licenses # prints [] not None. Comparison to lists is currently taken to mean "return objects whos collection contains these elements", i.e. its like a mass Account.licenses.contains() operator. So if you compare to an empty list that would return all parent elements. Comparison to None returns items using a "NOT EXISTS" clause, i.e. parent items with no child items. any() returns items where any of them meet the given criterion -since the criteiron is blank here, all child items match. any() is the best operator to use when asking for parents with no child items, using ~Account.licenses.any() (I think theres a tutorial example to this effect). Once loaded, all collection-based attributes default to the empty collection if no elements are present, which is by default a list. --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
