OpenStack Study: 029_location_meta_data_pickle_to_string.py

**** CubicPower OpenStack Study ****

def upgrade(migrate_engine):

    meta = sqlalchemy.schema.MetaData(migrate_engine)

    image_locations = Table('image_locations', meta, autoload=True)

    new_meta_data = Column('storage_meta_data', models.JSONEncodedDict,

                           default={})

    new_meta_data.create(image_locations)

    noe = pickle.dumps({})

    s = sqlalchemy.sql.select([image_locations]).\

        where(image_locations.c.meta_data != noe)

    conn = migrate_engine.connect()

    res = conn.execute(s)

    for row in res:

        meta_data = row['meta_data']

        x = pickle.loads(meta_data)

        if x != {}:

            stmt = image_locations.update().\

                where(image_locations.c.id == row['id']).\

                values(storage_meta_data=x)

            conn.execute(stmt)

    conn.close()

    image_locations.columns['meta_data'].drop()

    image_locations.columns['storage_meta_data'].alter(name='meta_data')

**** CubicPower OpenStack Study ****

def downgrade(migrate_engine):

    meta = sqlalchemy.schema.MetaData(migrate_engine)

    image_locations = Table('image_locations', meta, autoload=True)

    old_meta_data = Column('old_meta_data', sqlalchemy.PickleType(),

                           default={})

    old_meta_data.create(image_locations)

    noj = json.dumps({})

    s = sqlalchemy.sql.select([image_locations]).\

        where(image_locations.c.meta_data != noj)

    conn = migrate_engine.connect()

    res = conn.execute(s)

    for row in res:

        x = row['meta_data']

        meta_data = json.loads(x)

        if meta_data != {}:

            stmt = image_locations.update().\

                where(image_locations.c.id == row['id']).\

                values(old_meta_data=meta_data)

            conn.execute(stmt)

    conn.close()

    image_locations.columns['meta_data'].drop()

    image_locations.columns['old_meta_data'].alter(name='meta_data')