Ignore empty or None group/user in local role assignment

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@5222 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/ERP5Type.py

@@ -311,11 +311,14 @@ class ERP5TypeInformation( FactoryTypeInformation, RoleProviderBase ):
             role_group_dict = {}
             for category_dict in value_list:
                 group_id = group_id_generator(**category_dict)
+                # If group_id is not defined, do not use it
+                if group_id not in (None, ''):
                   if type(group_id) is type('a'):
-                  # Single group is defined
+                    # Single group is defined (this is usually for group membership)
                     role_group_dict[group_id] = 1
                   else:
-                  # Multiple users defined
+                    # Multiple groups are defined (this is usually for users)
+                    # but it could be extended to ad hoc groups
                     for user_id in group_id:
                       role_group_dict[user_id] = 1
             role_group_id_dict[role].extend(role_group_dict.keys())