After upgrading to 1.6 yesterday, our production instance is exhibiting
some odd behaviour with prefetch_related.
As the example below shows, when using prefetch_related on the foreign
field (viewed_cm), the returned instance apparently does not have this
foreign field set, even though the earlier filter on the queryset asserted
it had to exist.
>>> cb =
user.coursebookmark_set.filter(viewed_cm__course__type=course_type).prefetch_related('viewed_cm').latest('viewed_at')
>>> cb.viewed_cm
Traceback (most recent call last):
File "<console>", line 1, in <module>
File
"/home/ubuntu/app/ve-web/local/lib/python2.7/site-packages/django/db/models/fields/related.py",
line 314, in __get__
"%s has no %s." % (self.field.model.__name__, self.field.name))
DoesNotExist: CourseBookmark has no viewed_cm.
>>>
When prefetch_related is excluded, everything operates as expected.
>>> cb =
user.coursebookmark_set.filter(viewed_cm__course__type=course_type).latest('viewed_at')
>>> cb.viewed_cm
<CourseModule: py3-intro-calculating-things in intro-python-1>
>>>
Has anyone else experienced anything like this before? I can't seem to
replicate it not on production.
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