id,summary,reporter,owner,description,type,status,component,version,severity,resolution,keywords,cc,stage,has_patch,needs_docs,needs_tests,needs_better_patch,easy,ui_ux 22508,select_related on a foreign related object fails to load fields on original object,Malcolm Box,Aymeric Augustin,"Consider these models: {{{ class Show(models.Model): pass class Poll(models.Model): event = models.ForeignKey('Event') class Event(models.Model) show = models.ForeignKey(Show) }}} The following code fails to load the poll.event.show attribute: {{{ In [3]: event = Event.objects.all()[2] In [4]: poll = event.poll_set.select_related('event', 'event__show').all()[0] In [5]: hasattr(poll.event, '_show_cache') Out[5]: False }}} For comparison, in 1.4 the same code produces: {{{ In [12]: event = Event.objects.all()[2] In [13]: poll = event.poll_set.select_related('event', 'event__show').all()[0] In [14]: hasattr(poll.event, '_show_cache') Out[14]: True }}} The bug appears to be in the known_objects code around line 247 in db/models/query.py which looks like it will overwrite the poll.event attribute that was just retrieved from the DB (via select_related) and replaces it with the parent model, which in this case doesn't have the show attribute loaded. Since the ORM was explicitly instructed to load the Event model in the call, it shouldn't then replace the poll.event attribute with the previously-known parent model. ",Bug,closed,"Database layer (models, ORM)",1.6,Normal,fixed,,,Ready for checkin,1,0,0,0,0,0