new_contents: # coding=utf-8
  
  import types
  
  class NodeClean():
      '''
      #节点清理, 当Dictionary节点中没有数据的时候删除节点
      '''
      def __init__(self):
          pass
      
      def clean(self, node):
          '''
          #清理节点
          @param node: ndb节点
           
          @return 清理后的节点
          '''
          if type(node) == types.ListType:
              result = []
              for row in node:
                  if row != None and len(row) > 0:
                      result.append(row)
          elif type(node) == types.DictionaryType:
              result = {}
              for key in node:
                  value = node.get(key)
                  cleaned_value = self.clean(value)
                  if cleaned_value != None and len(cleaned_value) > 0:
                      result[key] = cleaned_value
          else:
              result = node
              
          return result
  
subject: Add node_clean to clean empty node item