#30000: Passing QuerySet constructed with .union() causes
ModelMultipleChoiceField
to return wrong values
-------------------------------------+-------------------------------------
Reporter: thoha | Owner: nobody
Type: Uncategorized | Status: new
Component: Forms | Version: 1.11
Severity: Normal | Resolution:
Keywords: queryset, union, | Triage Stage:
forms | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by thoha):
After some further testing it appears the unexpected behaviour comes from
the fact that UNION querysets cannot be filtered, which the
ModelMultipleChoiceField apparently does out of sight. Still, I believe
that the observed behaviour is undesired, and the field should either
accept the union queryset and work properly, or raise an exception if a
union queryset is passed.
I also found that using
{{{
union_queryset =
SelectableRecords.objects.filter(other_related_thing_name__in=other_related_things)
}}}
instead of the for-loop results in a queryset that actually works properly
with the ModelMultipleChoiceField. Based on
[https://stackoverflow.com/questions/50638442/django-queryset-union-
return-broken-queryset-filter-and-get-return-every this StackOverflow
question].
--
Ticket URL: <https://code.djangoproject.com/ticket/30000#comment:3>
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