#33984: Related managers cache gets stale after saving a fetched model with new
PK
-------------------------------------+-------------------------------------
Reporter: joeli | Owner: Bhuvnesh
Type: Bug | Status: assigned
Component: Database layer | Version: 4.1
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Mariusz Felisiak):
I found another regression in caching related manager. The following test
works on Django 4.0 and crashes with
4f8c7fd9d91b35e2c2922de4bb50c8c8066cbbc6:
{{{#!diff
diff --git a/tests/many_to_many/tests.py b/tests/many_to_many/tests.py
index 53e870ddad..770808a92c 100644
--- a/tests/many_to_many/tests.py
+++ b/tests/many_to_many/tests.py
@@ -92,6 +92,27 @@ class ManyToManyTests(TestCase):
a5.authors.remove(user_2.username)
self.assertSequenceEqual(a5.authors.all(), [])
+ def test_related_manager_refresh(self):
+ user_1 = User.objects.create(username="Jean")
+ user_2 = User.objects.create(username="Joe")
+ a5 = Article.objects.create(headline="Django lets you create web
apps easily")
+ a5.authors.add(user_1.username)
+ self.assertSequenceEqual(user_1.article_set.all(), [a5])
+ # Change the username on a different instance of the same user.
+ user_1_from_db = User.objects.get(pk=user_1.pk)
+ self.assertSequenceEqual(user_1_from_db.article_set.all(), [a5])
+ user_1_from_db.username = "Paul"
+ user_1_from_db.save()
+ user_2.username = "Jean"
+ user_2.save()
+ # Add a different article.
+ self.a4.authors.add(user_1_from_db.username)
+ self.assertSequenceEqual(user_1_from_db.article_set.all(),
[self.a4])
+ # Refresh the first instance from DB.
+ user_1.refresh_from_db()
+ self.assertEqual(user_1.username, "Paul")
+ self.assertSequenceEqual(user_1.article_set.all(), [self.a4])
+
def test_add_remove_invalid_type(self):
msg = "Field 'id' expected a number but got 'invalid'."
for method in ["add", "remove"]:
}}}
It shows two issues:
- the second call of `user_1_from_db.article_set.all()` should use a new
username (`Paul`) but it's still using the old one (`Jean`),
- `user_1.refresh_from_db()` doesn't clear cached managers.
I'm going to prepare revert of 4f8c7fd9d91b35e2c2922de4bb50c8c8066cbbc6
and reopen #32980.
--
Ticket URL: <https://code.djangoproject.com/ticket/33984#comment:14>
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