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author | Ian Foote <python@ian.feete.org> | 2015-11-06 20:18:00 +0100 |
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committer | Simon Charette <charette.s@gmail.com> | 2015-11-11 00:58:53 -0500 |
commit | 6184cb9baa8426ed8b3e1fb5d96afac809dd2a0c (patch) | |
tree | 2987ee8fdfe449b3ff3f70209497c956cd962819 | |
parent | 85a41b449bfe40307d1a9c482fc39dd1f82ba470 (diff) | |
download | django-6184cb9baa8426ed8b3e1fb5d96afac809dd2a0c.tar.gz |
[1.7.x] Fixed #25693 -- Prevented data loss with Prefetch and ManyToManyField.
Thanks to Jamie Matthews for finding and explaining the bug.
Backport of 4608573788c04fc047da42b4b7b48fdee8136ad3 from master
-rw-r--r-- | django/db/models/query.py | 8 | ||||
-rw-r--r-- | docs/releases/1.7.11.txt | 13 | ||||
-rw-r--r-- | docs/releases/index.txt | 1 | ||||
-rw-r--r-- | tests/prefetch_related/tests.py | 11 |
4 files changed, 33 insertions, 0 deletions
diff --git a/django/db/models/query.py b/django/db/models/query.py index 22919e504e..dca6eea1ba 100644 --- a/django/db/models/query.py +++ b/django/db/models/query.py @@ -1910,6 +1910,14 @@ def prefetch_one_level(instances, prefetcher, lookup, level): instance_attr_val = instance_attr(obj) vals = rel_obj_cache.get(instance_attr_val, []) to_attr, as_attr = lookup.get_current_to_attr(level) + + # Check we are not shadowing a field on obj. + if as_attr: + for related_m2m in obj._meta.get_all_related_many_to_many_objects(): + if related_m2m.get_accessor_name() == to_attr: + msg = 'to_attr={} conflicts with a field on the {} model.' + raise ValueError(msg.format(to_attr, obj.__class__.__name__)) + if single: val = vals[0] if vals else None to_attr = to_attr if as_attr else cache_name diff --git a/docs/releases/1.7.11.txt b/docs/releases/1.7.11.txt new file mode 100644 index 0000000000..7c6153eab1 --- /dev/null +++ b/docs/releases/1.7.11.txt @@ -0,0 +1,13 @@ +=========================== +Django 1.7.11 release notes +=========================== + +*Under development* + +Django 1.7.11 fixes a data loss bug in 1.7.10. + +Bugfixes +======== + +* Fixed a data loss possibility with :class:`~django.db.models.Prefetch` if + ``to_attr`` is set to a ``ManyToManyField`` (:ticket:`25693`). diff --git a/docs/releases/index.txt b/docs/releases/index.txt index a1447ea070..c76e1ae732 100644 --- a/docs/releases/index.txt +++ b/docs/releases/index.txt @@ -25,6 +25,7 @@ versions of the documentation contain the release notes for any later releases. .. toctree:: :maxdepth: 1 + 1.7.11 1.7.10 1.7.9 1.7.8 diff --git a/tests/prefetch_related/tests.py b/tests/prefetch_related/tests.py index 691067b8d6..83db7eb2ff 100644 --- a/tests/prefetch_related/tests.py +++ b/tests/prefetch_related/tests.py @@ -221,6 +221,17 @@ class PrefetchRelatedTests(TestCase): self.assertTrue('prefetch_related' in str(cm.exception)) self.assertTrue("name" in str(cm.exception)) + def test_m2m_shadow(self): + msg = 'to_attr=books conflicts with a field on the Author model.' + poems = Book.objects.filter(title='Poems') + with self.assertRaisesMessage(ValueError, msg): + list(Author.objects.prefetch_related( + Prefetch('books', queryset=poems, to_attr='books'), + )) + # Without the ValueError, a book was deleted due to the implicit + # save of reverse relation assignment. + self.assertEqual(self.author1.books.count(), 2) + class CustomPrefetchTests(TestCase): @classmethod |