#24279: ORing with an empty Q() produces inconsistent results ----------------------------------------------+--------------------------- Reporter: ris | Owner: nobody Type: Bug | Status: new Component: Database layer (models, ORM) | Version: 1.7 Severity: Normal | Keywords: Q empty in or Triage Stage: Unreviewed | Has patch: 0 Easy pickings: 0 | UI/UX: 0 ----------------------------------------------+--------------------------- Using django 1.7.4, postgres 9.1.
Minimal testcase models.py: {{{ from django.db import models class ModelA ( models.Model ): pass }}} then: {{{ >>> for i in xrange ( 1 , 5 ): ... ModelA.objects.create ( pk = i ) >>> ModelA.objects.filter ( Q ( pk__in = () ) ) [] }}} correctly returning no results. also {{{ >>> ModelA.objects.filter ( Q ( pk__in = (1,2,) ) | Q () ) [<ModelA: 1>, <ModelA: 2>] }}} again, correct however {{{ >>> ModelA.objects.filter ( Q ( pk__in = () ) | Q () ) [<ModelA: 1>, <ModelA: 2>, <ModelA: 3>, <ModelA: 4>] }}} where I would have expected no instances to be returned. The empty Q here has the effect of turning the {{{pk__in}}} into a no-op. Interestingly, reformulating it as a (no-result-returning) subquery produces the expected result: {{{ >>> ModelA.objects.filter ( Q ( pk__in = ModelA.objects.filter ( pk__isnull = True ) ) | Q () ) [] }}} I realize that OR'ing with an empty Q may not be something you're really supposed to do, but sometimes it does happen and this behaviour is quite unexpected. Apologies if this is a duplicate but I was unable to find an existing ticket covering this. -- Ticket URL: <https://code.djangoproject.com/ticket/24279> Django <https://code.djangoproject.com/> The Web framework for perfectionists with deadlines. -- You received this message because you are subscribed to the Google Groups "Django updates" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-updates+unsubscr...@googlegroups.com. To post to this group, send email to django-updates@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-updates/046.33e34609d6bd6f96804972d53d6b86dc%40djangoproject.com. For more options, visit https://groups.google.com/d/optout.