allow for skipping certain fields when checking for empty rows

composer/schema/grid/field.py

@@ -127,7 +127,11 @@ class GridFieldInstance(ListFieldInstance):
                     continue
             if value:
                 item[fi.name] = value
+        ignoreInCheckOnEmpty = getattr(self.context, 'ignoreInCheckOnEmpty', [])
+        for k, v in item.items():
+            if k not in ignoreInCheckOnEmpty and v != '__no_change__':
                 return item
+        return {}
 
 
 class RecordsFieldInstance(GridFieldInstance):

composer/schema/grid/interfaces.py

@@ -1,5 +1,5 @@
 #
-#  Copyright (c) 2011 Helmut Merz helmutm@cy55.de
+#  Copyright (c) 2013 Helmut Merz helmutm@cy55.de
 #
 #  This program is free software; you can redistribute it and/or modify
 #  it under the terms of the GNU General Public License as published by
@@ -38,6 +38,7 @@ class Grid(schema.List):
                               instanceName='grid'))
 
     column_types = []
+    ignoreInCheckOnEmpty = []
     cardinality = None