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Code Issues 25 Releases Wiki Activity

Fixed #33159 -- Reverted "Fixed #32970 -- Changed WhereNode.clone() to create a shallow copy of children."

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This reverts commit e441847eca.

A shallow copy is not enough because querysets can be reused and
evaluated in nested nodes, which shouldn't mutate JOIN aliases.

Thanks Michal Čihař for the report.
This commit is contained in:
Mariusz Felisiak 2021-09-30 11:26:17 +02:00 committed by GitHub
parent dd1fa3a31b
commit 903aaa35e5
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 11 additions and 1 deletions
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6
django/db/models/sql/where.py
View File

@ -148,7 +148,11 @@ class WhereNode(tree.Node):
clone = self.__class__._new_instance(
children=None, connector=self.connector, negated=self.negated,
)
clone.children = self.children[:]
for child in self.children:
if hasattr(child, 'clone'):
clone.children.append(child.clone())
else:
clone.children.append(child)
return clone
def relabeled_clone(self, change_map):

6
tests/queries/tests.py
View File

@ -1663,6 +1663,12 @@ class Queries5Tests(TestCase):
'bar %s'
)
def test_queryset_reuse(self):
# Using querysets doesn't mutate aliases.
authors = Author.objects.filter(Q(name='a1') | Q(name='nonexistent'))
self.assertEqual(Ranking.objects.filter(author__in=authors).get(), self.rank3)
self.assertEqual(authors.count(), 1)
class SelectRelatedTests(TestCase):
def test_tickets_3045_3288(self):