''

def update(self, subject_id, entity_id, ava):

    item = self._cache.find_one({'subject_id': subject_id, 'entity_id': entity_id})
    info = item['info']
    info['ava'].update(ava)
    self._cache.update({'subject_id': subject_id, 'entity_id': entity_id}, {'$set': {'info': info}})
