One day I'll stop posting in this thread. Really. On Sat, 2009-03-07 at 12:03 +1100, Malcolm Tredinnick wrote:
> However, find things that are simultaneously in all those categories can > be done without all the annotation nonsense I posted. Simply > > > Publication.objects.filter(article=1).filter(article=2).filter(article=3) > > It's a short loop to build up such a set dynamically. The difference > between that (3 filter calls) and you Q-object version is described in > the documentation: > http://docs.djangoproject.com/en/dev/topics/db/queries/#spanning-multi-valued-relationships I forgot to mention that this approach is probably only practical for a small number of article instances. Each filter() adds a new table join, so at some point the database will complain. Either literally, about too many joins, or by taking ages to attempt to optimise and execute the query. For a large number of article instances, the annotation-based solution I gave earlier is more appropriate. Regards, Malcolm --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
