Ticket #3873: django.2.diff

django/db/models/manipulators.py

@@ -242 +242 @@
 
     def flatten_data(self):
         new_data = {}
-        obj = self.change and self.original_object or None
+        if self.change:
+            obj = self.original_object
+        else:
+            obj = None
         for f in self.opts.get_data_holders(self.follow):
             fol = self.follow.get(f.name)
             new_data.update(f.flatten_data(fol, obj))

django/db/models/fields/__init__.py

@@ -311 +311 @@
             return self.get_choices()
 
     def _get_val_from_obj(self, obj):
-        if obj:
+        if obj is not None:
             return getattr(obj, self.attname)
         else:
             return self.get_default()