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Fixed #28198 -- Prevented model attributes from overriding deferred fields. #9126

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@@ -75,6 +75,23 @@ def __new__(cls, name, bases, attrs, **kwargs):
classcell = attrs.pop('__classcell__', None)
if classcell is not None:
new_attrs['__classcell__'] = classcell
# Fixed #28198 -- Model attributes does not overridden by
# attributes from parent classes
# For each parent class collect and remove the attributes which
# present in `attrs` and has implementation in this parent class
duplicate_attributes = {}
for parent in parents:
attributes_per_parent_class = {}
for attr_name in attrs:
if(hasattr(parent, attr_name) and not
attr_name.startswith(LOOKUP_SEP) and not
hasattr(getattr(parent, attr_name), '__dict__')
attributes_per_parent_class[attr_name] = getattr(parent, attr_name)
delattr(parent, attr_name)
if len(attributes_per_parent_class) > 0:
duplicate_attributes[parent] = attributes_per_parent_class
new_class = super_new(cls, name, bases, new_attrs, **kwargs)
attr_meta = attrs.pop('Meta', None)
abstract = getattr(attr_meta, 'abstract', False)
@@ -287,6 +304,14 @@ def __new__(cls, name, bases, attrs, **kwargs):
# abstract model.
new_class._meta.indexes = [copy.deepcopy(idx) for idx in new_class._meta.indexes]
# Fixed #28198 -- Model attributes does not overridden by
# attributes from parent classes
# Restore the attributes for each model parent class
if len(duplicate_attributes) > 0:
for parent in parents:
if parent in duplicate_attributes:
for attribute in duplicate_attributes[parent]:
setattr(parent, attribute, duplicate_attributes[parent][attribute])
if abstract:
# Abstract base models can't be instantiated and don't appear in
# the list of models for an app. We do the final setup for them a
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@@ -14,6 +14,7 @@ class Primary(models.Model):
name = models.CharField(max_length=50)
value = models.CharField(max_length=50)
related = models.ForeignKey(Secondary, models.CASCADE)
other = True
def __str__(self):
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@@ -271,3 +271,23 @@ def test_custom_refresh_on_deferred_loading(self):
# access of any of them.
self.assertEqual(, 'new foo')
self.assertEqual(rf2.value, 'new bar')
def test_field_not_overridden_by_parent(self):
Fixed #28198 -- Model attributes does not overridden by
attributes from parent classes
The defer field `other` must return value from db, instead
attribute value from parent model.
The attribute `other` for Child must be the same
as in parent model
s = Secondary.objects.create()
Child.objects.create(name='foo', value='bar', related=s)
BigChild.objects.create(other="False", related=s)
primary = Child.objects.get()
big_child = BigChild.objects.defer('other').get()
self.assertEqual(len(big_child.get_deferred_fields()), 1)
self.assertIs(primary.other, True)
self.assertEqual(big_child.other, "False")
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