ADD operation patch for boto.dynamodb2.items.Item

gistfile1.diff

--- /usr/local/lib/python2.7/site-packages/boto/dynamodb2/items.py.bak  2015-03-24 17:46:20.000000000 +0900
+++ /usr/local/lib/python2.7/site-packages/boto/dynamodb2/items.py  2015-03-24 18:29:56.000000000 +0900
@@ -1,5 +1,5 @@
 from copy import deepcopy
-
+from decimal import Decimal
 class NEWVALUE(object):
     # A marker for new data added.
@@ -352,9 +352,22 @@
             fields.add(key)
         for key, value in alterations['changes'].items():
+            # fix to add
+            action = 'PUT'
+            value  = self._data[key]
+            org_value = self._orig_data[key]
+            if type(value) == type(org_value):
+                if type(value) == list:
+                    if org_value == value[:len(org_value)]: # values have been changed
+                        action = 'ADD'
+                        value = value[len(org_value):]
+                elif type(value) in (set, int, float, Decimal):
+                    action = 'ADD'
+                    value = value - org_value
+
             final_data[key] = {
-                'Action': 'PUT',
-                'Value': self._dynamizer.encode(self._data[key])
+                'Action': action,
+                'Value': self._dynamizer.encode(value)
             }
             fields.add(key)