[1.8.x] Fixed #24958 -- Fixed inline forms using UUID-PK parents with auto-PK children.

Backport of a50b66da30 from master

django/forms/models.py

@@ -922,10 +922,15 @@ class BaseInlineFormSet(BaseModelFormSet):
             if self.fk.rel.field_name != self.fk.rel.to._meta.pk.name:
                 kwargs['to_field'] = self.fk.rel.field_name
 
-        # If we're adding a new object, ignore a parent's auto-generated pk
+        # If we're adding a new object, ignore a parent's auto-generated key
         # as it will be regenerated on the save request.
-        if self.instance._state.adding and form._meta.model._meta.pk.has_default():
-            self.instance.pk = None
+        if self.instance._state.adding:
+            if kwargs.get('to_field') is not None:
+                to_field = self.instance._meta.get_field(kwargs['to_field'])
+            else:
+                to_field = self.instance._meta.pk
+            if to_field.has_default():
+                setattr(self.instance, to_field.attname, None)
 
         form.fields[name] = InlineForeignKeyField(self.instance, **kwargs)
 

docs/releases/1.8.3.txt

@@ -85,3 +85,7 @@ Bugfixes
 
 * Reallowed non-ASCII values for ``ForeignKey.related_name`` on Python 3 by
   fixing the false positive system check (:ticket:`25016`).
+
+* Fixed inline forms that use a parent object that has a ``UUIDField`` primary
+  key and a child object that has an ``AutoField`` primary key
+  (:ticket:`24958`).

tests/model_formsets/models.py

@@ -254,3 +254,33 @@ class UUIDPKChild(models.Model):
     uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
     name = models.CharField(max_length=255)
     parent = models.ForeignKey(UUIDPKParent)
+
+
+class ChildWithEditablePK(models.Model):
+    name = models.CharField(max_length=255, primary_key=True)
+    parent = models.ForeignKey(UUIDPKParent)
+
+
+class AutoPKChildOfUUIDPKParent(models.Model):
+    name = models.CharField(max_length=255)
+    parent = models.ForeignKey(UUIDPKParent)
+
+
+class AutoPKParent(models.Model):
+    name = models.CharField(max_length=255)
+
+
+class UUIDPKChildOfAutoPKParent(models.Model):
+    uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    name = models.CharField(max_length=255)
+    parent = models.ForeignKey(AutoPKParent)
+
+
+class ParentWithUUIDAlternateKey(models.Model):
+    uuid = models.UUIDField(unique=True, default=uuid.uuid4, editable=False)
+    name = models.CharField(max_length=50)
+
+
+class ChildRelatedViaAK(models.Model):
+    name = models.CharField(max_length=255)
+    parent = models.ForeignKey(to=ParentWithUUIDAlternateKey, to_field='uuid')

tests/model_formsets/test_uuid.py

@@ -1,7 +1,11 @@
 from django.forms.models import inlineformset_factory
 from django.test import TestCase
 
-from .models import UUIDPKChild, UUIDPKParent
+from .models import (
+    AutoPKChildOfUUIDPKParent, AutoPKParent, ChildRelatedViaAK,
+    ChildWithEditablePK, ParentWithUUIDAlternateKey, UUIDPKChild,
+    UUIDPKChildOfAutoPKParent, UUIDPKParent,
+)
 
 
 class InlineFormsetTests(TestCase):
@@ -10,6 +14,8 @@ class InlineFormsetTests(TestCase):
         #24377 - If we're adding a new object, a parent's auto-generated pk
         from the model field default should be ignored as it's regenerated on
         the save request.
+
+        Tests the case where both the parent and child have a UUID primary key.
         """
         FormSet = inlineformset_factory(UUIDPKParent, UUIDPKChild, fields='__all__')
         formset = FormSet()
@@ -30,3 +36,43 @@ class InlineFormsetTests(TestCase):
             'uuidpkchild_set-2-name': '',
         })
         self.assertTrue(formset.is_valid())
+
+    def test_inlineformset_factory_nulls_default_pks_uuid_parent_auto_child(self):
+        """
+        #24958 - Variant of test_inlineformset_factory_nulls_default_pks for
+        the case of a parent object with a UUID primary key and a child object
+        with an AutoField primary key.
+        """
+        FormSet = inlineformset_factory(UUIDPKParent, AutoPKChildOfUUIDPKParent, fields='__all__')
+        formset = FormSet()
+        self.assertIsNone(formset.forms[0].fields['parent'].initial)
+
+    def test_inlineformset_factory_nulls_default_pks_auto_parent_uuid_child(self):
+        """
+        #24958 - Variant of test_inlineformset_factory_nulls_default_pks for
+        the case of a parent object with an AutoField primary key and a child
+        object with a UUID primary key.
+        """
+        FormSet = inlineformset_factory(AutoPKParent, UUIDPKChildOfAutoPKParent, fields='__all__')
+        formset = FormSet()
+        self.assertIsNone(formset.forms[0].fields['parent'].initial)
+
+    def test_inlineformset_factory_nulls_default_pks_child_editable_pk(self):
+        """
+        #24958 - Variant of test_inlineformset_factory_nulls_default_pks for
+        the case of a parent object with a UUID primary key and a child
+        object with an editable natural key for a primary key.
+        """
+        FormSet = inlineformset_factory(UUIDPKParent, ChildWithEditablePK, fields='__all__')
+        formset = FormSet()
+        self.assertIsNone(formset.forms[0].fields['parent'].initial)
+
+    def test_inlineformset_factory_nulls_default_pks_alternate_key_relation(self):
+        """
+        #24958 - Variant of test_inlineformset_factory_nulls_default_pks for
+        the case of a parent object with a UUID alternate key and a child
+        object that relates to that alternate key.
+        """
+        FormSet = inlineformset_factory(ParentWithUUIDAlternateKey, ChildRelatedViaAK, fields='__all__')
+        formset = FormSet()
+        self.assertIsNone(formset.forms[0].fields['parent'].initial)