Ticket #13794: fix_inline_model_with_to_field.diff

django/forms/models.py

@@ -716 +716 @@
 
             # Remove the foreign key from the form's data
             form.data[form.add_prefix(self.fk.name)] = None
-
-        # Set the fk value here so that the form can do it's validation.
-        setattr(form.instance, self.fk.get_attname(), self.instance.pk)
         return form
 
     #@classmethod

tests/regressiontests/model_formsets_regress/tests.py

@@ -156 +156 @@
         # you can create a formset with an instance of None
         form = Form(instance=None)
         formset = FormSet(instance=None)
+
+    def test_inline_model_with_to_field(self):
+        "An inline model with a to_field of a formset with instance have working relations. Regression for #13794"
+        FormSet = inlineformset_factory(User, UserSite)
+
+        user = User.objects.create(username="guido", serial=1337)
+        UserSite.objects.create(user=user, data=10)
+        formset = FormSet(instance=user)
+
+        original_site1 = formset.get_queryset()[0]
+
+        # Testing the inline model's relation
+        self.assertEqual(original_site1.user.username, "guido")