#29694: QuerySet.values_list() combined with .extra() or .annotate() may produce
wrong .union()
-------------------------------------+-------------------------------------
Reporter: master | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.11
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: union values_list | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by master):
(I wasn't sure and I don't mind to reopen a previous ticket, but my
reasoning to open a new ticket was exactly the one of Tim).
So why didn't the test case (test_union_with_two_annotated_values_list)
fail after the changes of #29286? Because it is written with annotate()
instead of extra(). To reproduce the steps of the demo code of #29229,
replace:
{{{
#!python
qs1 = Number.objects.filter(num=1).annotate(count=Value(0,
IntegerField()),).values_list('num', 'count')
}}}
by:
{{{
#!python
qs1 = Number.objects.filter(num=1).extra(select={'count':
0}).values_list('num', 'count')
}}}
Note: I just discovered that the usage of extra() is discouraged, and I
will consider a replacement, but not as a priority.
My suggestion for a fix in
django\db\models\sql\compiler.py\get_combinator_sql(), to work both with
extra and annotate, is something of this kind:
{{{
#!python
if (not compiler.query.values_select and not compiler.query.annotations
and (self.query.values_select or self.query.annotation_select or
self.query.extra_select)):
compiler.query.set_values(tuple(self.query.values_select) +
tuple(self.query.annotation_select) +
tuple(self.query.extra_select)
)
}}}
I'm not sure if we need the additional condition "and not
compiler.query.<extra>", as I don't know what <extra> would be amongst:
"extra", "extra_select" and "_extra".
--
Ticket URL: <https://code.djangoproject.com/ticket/29694#comment:3>
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