#33282: django.db.utils.ProgrammingError: more than one row returned by a
subquery
used as an expression
-------------------------------------+-------------------------------------
Reporter: Antonio Terceiro | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 3.2
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 1 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Simon Charette):
* stage: Unreviewed => Accepted
Comment:
Managed to reproduce with this tests
{{{#!diff
diff --git a/tests/aggregation/tests.py b/tests/aggregation/tests.py
index 9ba70cb35e..f3277d2b5f 100644
--- a/tests/aggregation/tests.py
+++ b/tests/aggregation/tests.py
@@ -1335,6 +1335,14 @@ def
test_aggregation_nested_subquery_outerref(self):
).values_list('publisher_count', flat=True)
self.assertSequenceEqual(books_breakdown, [1] * 6)
+ def test_filter_in_subquery_or_aggregation(self):
+ authors = Author.objects.annotate(
+ books_count=Count('book'),
+ ).filter(
+ Q(pk__in=Book.objects.values('authors')) |
Q(books_count__gt=0)
+ )
+ self.assertQuerysetEqual(authors, Author.objects.all(),
ordered=False)
+
def test_aggregation_random_ordering(self):
"""Random() is not included in the GROUP BY when used for
ordering."""
authors =
Author.objects.annotate(contact_count=Count('book')).order_by('?')
}}}
The gist of it is that the logic that was added to
`Subquery.get_group_by_cols` should have been added to
`sql.Query.get_group_by_cols` and the latter should have proxied it.
The issue is triggered when a lookup containing a subquery is combined
using `OR` to a lookup against an aggregation. When this happens the ORM
has to choice but to push the filtering to the `HAVING` clause and thus
group by all inputs passed down to the lookups. Since `Subquery` resolves
to `sql.Query` and the latter defaults to returning `self` as inherited
from `BaseExpression` the ORM tries to group by a subquery that
potentially returns multiple rows.
Antonio if don't mind if I assign the issue to me I have a patch set
almost ready to address the problem and include extra regression tests for
new uses cases such as lookup annotations which is a newly supported in
4.0.
--
Ticket URL: <https://code.djangoproject.com/ticket/33282#comment:8>
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