Fixed #24974 -- Fixed inheritance of formfield_callback for modelform_factory forms.

django/forms/models.py

@@ -209,7 +209,13 @@ class ModelFormOptions(object):
 
 class ModelFormMetaclass(DeclarativeFieldsMetaclass):
     def __new__(mcs, name, bases, attrs):
-        formfield_callback = attrs.pop('formfield_callback', None)
+        base_formfield_callback = None
+        for b in bases:
+            if hasattr(b, 'Meta') and hasattr(b.Meta, 'formfield_callback'):
+                base_formfield_callback = b.Meta.formfield_callback
+                break
+
+        formfield_callback = attrs.pop('formfield_callback', base_formfield_callback)
 
         new_class = super(ModelFormMetaclass, mcs).__new__(mcs, name, bases, attrs)
 
@@ -530,7 +536,8 @@ def modelform_factory(model, form=ModelForm, fields=None, exclude=None,
     if hasattr(form, 'Meta'):
         parent = (form.Meta, object)
     Meta = type(str('Meta'), parent, attrs)
-
+    if formfield_callback:
+        Meta.formfield_callback = staticmethod(formfield_callback)
     # Give this new form class a reasonable name.
     class_name = model.__name__ + str('Form')
 

tests/model_forms/tests.py

@@ -2736,6 +2736,28 @@ class FormFieldCallbackTests(SimpleTestCase):
         with self.assertRaises(TypeError):
             modelform_factory(Person, fields="__all__", formfield_callback='not a function or callable')
 
+    def test_inherit_after_custom_callback(self):
+        def callback(db_field, **kwargs):
+            if isinstance(db_field, models.CharField):
+                return forms.CharField(widget=forms.Textarea)
+            return db_field.formfield(**kwargs)
+
+        class BaseForm(forms.ModelForm):
+            class Meta:
+                model = Person
+                fields = '__all__'
+
+        NewForm = modelform_factory(Person, form=BaseForm, formfield_callback=callback)
+
+        class InheritedForm(NewForm):
+            pass
+
+        for name in NewForm.base_fields.keys():
+            self.assertEqual(
+                type(InheritedForm.base_fields[name].widget),
+                type(NewForm.base_fields[name].widget)
+            )
+
 
 class LocalizedModelFormTest(TestCase):
     def test_model_form_applies_localize_to_some_fields(self):