old_contents: # Copyright 2011 OpenStack LLC.
  #
  #    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 Column, Integer, MetaData, Table
  from migrate import ForeignKeyConstraint
  
  from nova import log as logging
  
  meta = MetaData()
  
  
  def upgrade(migrate_engine):
      # Upgrade operations go here. Don't create your own engine;
      # bind migrate_engine to your metadata
      meta.bind = migrate_engine
      dialect = migrate_engine.url.get_dialect().name
      if dialect.startswith('sqlite'):
          return
  
      instances = Table('instances', meta, autoload=True)
      vifs = Table('virtual_interfaces', meta, autoload=True)
  
      try:
          fkey_name = vifs.c.instance_id.foreign_keys[0].constraint.name
          ForeignKeyConstraint(columns=[vifs.c.instance_id],
                               refcolumns=[instances.c.id],
                               name=fkey_name).drop()
  
      except Exception:
          logging.error(_("foreign key constraint couldn't be removed"))
          raise
  
  
  def downgrade(migrate_engine):
      # Operations to reverse the above upgrade go here.
      meta.bind = migrate_engine
      dialect = migrate_engine.url.get_dialect().name
      if dialect.startswith('sqlite'):
          return
  
      instances = Table('instances', meta, autoload=True)
      vifs = Table('virtual_interfaces', meta, autoload=True)
  
      try:
          ForeignKeyConstraint(columns=[vifs.c.instance_id],
                               refcolumns=[instances.c.id]).create()
      except Exception:
          logging.error(_("foreign key constraint couldn't be added"))
          raise
  
new_contents: # Copyright 2011 OpenStack LLC.
  #
  #    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 Column, Integer, MetaData, Table
  from migrate import ForeignKeyConstraint
  
  from nova import log as logging
  
  meta = MetaData()
  
  
  def upgrade(migrate_engine):
      # Upgrade operations go here. Don't create your own engine;
      # bind migrate_engine to your metadata
      meta.bind = migrate_engine
      dialect = migrate_engine.url.get_dialect().name
      if dialect.startswith('sqlite'):
          return
  
      instances = Table('instances', meta, autoload=True)
      vifs = Table('virtual_interfaces', meta, autoload=True)
  
      try:
          fkey_name = list(vifs.c.instance_id.foreign_keys)[0].constraint.name
          ForeignKeyConstraint(columns=[vifs.c.instance_id],
                               refcolumns=[instances.c.id],
                               name=fkey_name).drop()
  
      except Exception:
          logging.error(_("foreign key constraint couldn't be removed"))
          raise
  
  
  def downgrade(migrate_engine):
      # Operations to reverse the above upgrade go here.
      meta.bind = migrate_engine
      dialect = migrate_engine.url.get_dialect().name
      if dialect.startswith('sqlite'):
          return
  
      instances = Table('instances', meta, autoload=True)
      vifs = Table('virtual_interfaces', meta, autoload=True)
  
      try:
          ForeignKeyConstraint(columns=[vifs.c.instance_id],
                               refcolumns=[instances.c.id]).create()
      except Exception:
          logging.error(_("foreign key constraint couldn't be added"))
          raise
  
subject: Fix 047 migration with SQLAlchemy 0.7.2