old_contents: #    Copyright 2013 IBM Corp.
  #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  from nova import db
  from nova.objects import base
  
  
  class InstanceInfoCache(base.NovaObject):
      fields = {
          'instance_uuid': str,
          'network_info': str,
          }
  
      @staticmethod
      def _from_db_object(context, info_cache, db_obj):
          info_cache.instance_uuid = db_obj['instance_uuid']
          info_cache.network_info = db_obj['network_info']
          info_cache.obj_reset_changes()
          info_cache._context = context
          return info_cache
  
      @base.remotable_classmethod
      def get_by_instance_uuid(cls, context, instance_uuid):
          db_obj = db.instance_info_cache_get(context, instance_uuid)
          return InstanceInfoCache._from_db_object(context, cls(), db_obj)
  
      @base.remotable
      def save(self, context):
          if 'network_info' in self.obj_what_changed():
              db.instance_info_cache_update(context, self.instance_uuid,
                                            {'network_info': self.network_info})
              self.obj_reset_changes()
  
new_contents: #    Copyright 2013 IBM Corp.
  #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  from nova import db
  from nova.objects import base
  from nova.objects import utils
  
  
  class InstanceInfoCache(base.NovaObject):
      fields = {
          'instance_uuid': str,
          'network_info': utils.str_or_none,
          }
  
      @staticmethod
      def _from_db_object(context, info_cache, db_obj):
          info_cache.instance_uuid = db_obj['instance_uuid']
          info_cache.network_info = db_obj['network_info']
          info_cache.obj_reset_changes()
          info_cache._context = context
          return info_cache
  
      @base.remotable_classmethod
      def get_by_instance_uuid(cls, context, instance_uuid):
          db_obj = db.instance_info_cache_get(context, instance_uuid)
          return InstanceInfoCache._from_db_object(context, cls(), db_obj)
  
      @base.remotable
      def save(self, context):
          if 'network_info' in self.obj_what_changed():
              db.instance_info_cache_update(context, self.instance_uuid,
                                            {'network_info': self.network_info})
              self.obj_reset_changes()
  
subject: Make info_cache handle when network_info is None