text: #    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 sqlalchemy import Boolean, Column, MetaData, Table, String
  
  
  def upgrade(migrate_engine):
      """Add columns to the transfers table.
  
      Add source_project_id, destination_project_id and accepted columns to the
      transfers table to improve volume transfer records.
      """
      meta = MetaData(bind=migrate_engine)
      transfers = Table('transfers', meta, autoload=True)
  
      if not hasattr(transfers.c, 'source_project_id'):
          transfers.create_column(Column('source_project_id', String(255),
                                         nullable=True))
  
      if not hasattr(transfers.c, 'destination_project_id'):
          transfers.create_column(Column('destination_project_id', String(255),
                                         nullable=True))
  
      if not hasattr(transfers.c, 'accepted'):
          transfers.create_column(Column('accepted', Boolean, default=False))
  