None may not be always considered as a NULL value of property, so it's better...

None may not be always considered as a NULL value of property, so it's better to take a default NULL value from _null.
Value is considered a NULL if inside _null.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@13562 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Accessor/Base.py

@@ -143,8 +143,9 @@ class Getter(Method):
         default = args[0]
       else:
         default = self._default
-      value = getattr(aq_base(instance), self._storage_id, None) # No acquisition on properties
-      if value is not None:
+      # No acquisition on properties
+      value = getattr(aq_base(instance), self._storage_id, self._null[0])
+      if value not in self._null:
         if self._is_tales_type and kw.get('evaluate', 1):
           return evaluateTales(instance, value)
         else: