Fixed #29998 -- Allowed multiple OneToOneFields to the parent model.

We assumed that any OneToOneField's in a child model must be the
parent link and raised an error when parent_link=True was not
specified. This patch allows to specify multiple OneToOneField's to
the parent model.

OneToOneField's without a custom related_name will raise fields.E304
and fields.E305 so this should warn users when they try to override
the auto-created OneToOneField.

1 files changed, 27 insertions, 0 deletions

diff --git a/tests/invalid_models_tests/test_relative_fields.py b/tests/invalid_models_tests/test_relative_fields.py
index 4ac0c547a9..786573672f 100644
--- a/tests/invalid_models_tests/test_relative_fields.py
+++ b/tests/invalid_models_tests/test_relative_fields.py
@@ -1291,6 +1291,33 @@ class ComplexClashTests(SimpleTestCase):
             ),
         ])
 
+    def test_clash_parent_link(self):
+        class Parent(models.Model):
+            pass
+
+        class Child(Parent):
+            other_parent = models.OneToOneField(Parent, models.CASCADE)
+
+        errors = [
+            ('fields.E304', 'accessor', 'parent_ptr', 'other_parent'),
+            ('fields.E305', 'query name', 'parent_ptr', 'other_parent'),
+            ('fields.E304', 'accessor', 'other_parent', 'parent_ptr'),
+            ('fields.E305', 'query name', 'other_parent', 'parent_ptr'),
+        ]
+        self.assertEqual(Child.check(), [
+            Error(
+                "Reverse %s for 'Child.%s' clashes with reverse %s for "
+                "'Child.%s'." % (attr, field_name, attr, clash_name),
+                hint=(
+                    "Add or change a related_name argument to the definition "
+                    "for 'Child.%s' or 'Child.%s'." % (field_name, clash_name)
+                ),
+                obj=Child._meta.get_field(field_name),
+                id=error_id,
+            )
+            for error_id, attr, field_name, clash_name in errors
+        ])
+
 
 @isolate_apps('invalid_models_tests')
 class M2mThroughFieldsTests(SimpleTestCase):