From fd1426570e7601128745d0e524704412c4431749 Mon Sep 17 00:00:00 2001 From: Simon Charette Date: Wed, 11 Nov 2015 00:49:35 -0500 Subject: [PATCH] [1.7.x] Refs #25693 -- Added a regression test for `to_attr` validation on forward m2m. Backport of cc8c02fa0fa2119704d1c39ca8509850aef84acc from master --- django/db/models/query.py | 20 +++++++++++++++----- tests/prefetch_related/tests.py | 13 ++++++++++++- 2 files changed, 27 insertions(+), 6 deletions(-) diff --git a/django/db/models/query.py b/django/db/models/query.py index ac68bec0dd..a81ee569f6 100644 --- a/django/db/models/query.py +++ b/django/db/models/query.py @@ -10,7 +10,7 @@ from django.conf import settings from django.core import exceptions from django.db import connections, router, transaction, IntegrityError from django.db.models.constants import LOOKUP_SEP -from django.db.models.fields import AutoField, Empty +from django.db.models.fields import AutoField, Empty, FieldDoesNotExist from django.db.models.query_utils import (Q, select_related_descend, deferred_class_factory, InvalidQuery) from django.db.models.deletion import Collector @@ -1912,10 +1912,20 @@ def prefetch_one_level(instances, prefetcher, lookup, level): # We assume that objects retrieved are homogeneous (which is the premise # of prefetch_related), so what applies to first object applies to all. model = instances[0].__class__ - for related_m2m in model._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, model.__name__)) + opts = model._meta + conflicts = False + try: + opts.get_field(to_attr) + except FieldDoesNotExist: + for related_m2m in opts.get_all_related_many_to_many_objects(): + if related_m2m.get_accessor_name() == to_attr: + conflicts = True + break + else: + conflicts = True + if conflicts: + msg = 'to_attr={} conflicts with a field on the {} model.' + raise ValueError(msg.format(to_attr, model.__name__)) for obj in instances: instance_attr_val = instance_attr(obj) diff --git a/tests/prefetch_related/tests.py b/tests/prefetch_related/tests.py index 83db7eb2ff..86240f64ad 100644 --- a/tests/prefetch_related/tests.py +++ b/tests/prefetch_related/tests.py @@ -221,7 +221,18 @@ class PrefetchRelatedTests(TestCase): self.assertTrue('prefetch_related' in str(cm.exception)) self.assertTrue("name" in str(cm.exception)) - def test_m2m_shadow(self): + def test_forward_m2m_to_attr_conflict(self): + msg = 'to_attr=authors conflicts with a field on the Book model.' + authors = Author.objects.all() + with self.assertRaisesMessage(ValueError, msg): + list(Book.objects.prefetch_related( + Prefetch('authors', queryset=authors, to_attr='authors'), + )) + # Without the ValueError, an author was deleted due to the implicit + # save of the relation assignment. + self.assertEqual(self.book1.authors.count(), 3) + + def test_reverse_m2m_to_attr_conflict(self): msg = 'to_attr=books conflicts with a field on the Author model.' poems = Book.objects.filter(title='Poems') with self.assertRaisesMessage(ValueError, msg):