¡@
OpenStack Study: 003_add_disk_format.py**** CubicPower OpenStack Study **** def get_images_table(meta): """ Returns the Table object for the images table that corresponds to the images table definition of this version. """ images = Table('images', meta, Column('id', Integer(), primary_key=True, nullable=False), Column('name', String(255)), Column('disk_format', String(20)), Column('container_format', String(20)), Column('size', Integer()), Column('status', String(30), nullable=False), Column('is_public', Boolean(), nullable=False, default=False, index=True), Column('location', Text()), Column('created_at', DateTime(), nullable=False), Column('updated_at', DateTime()), Column('deleted_at', DateTime()), Column('deleted', Boolean(), nullable=False, default=False, index=True), mysql_engine='InnoDB', extend_existing=True) return images
**** CubicPower OpenStack Study **** def get_image_properties_table(meta): """ No changes to the image properties table from 002... """ (define_image_properties_table,) = from_migration_import( '002_add_image_properties_table', ['define_image_properties_table']) image_properties = define_image_properties_table(meta) return image_properties
**** CubicPower OpenStack Study **** def upgrade(migrate_engine): meta = MetaData() meta.bind = migrate_engine (define_images_table,) = from_migration_import( '001_add_images_table', ['define_images_table']) (define_image_properties_table,) = from_migration_import( '002_add_image_properties_table', ['define_image_properties_table']) conn = migrate_engine.connect() images = define_images_table(meta) image_properties = define_image_properties_table(meta) # Steps to take, in this order: # 1) Move the existing type column from Image into # ImageProperty for all image records that have a non-NULL # type column # 2) Drop the type column in images # 3) Add the new columns to images # The below wackiness correlates to the following ANSI SQL: # SELECT images.* FROM images # LEFT JOIN image_properties # ON images.id = image_properties.image_id # AND image_properties.key = 'type' # WHERE image_properties.image_id IS NULL # AND images.type IS NOT NULL # # which returns all the images that have a type set # but that DO NOT yet have an image_property record # with key of type. from_stmt = [ images.outerjoin(image_properties, and_(images.c.id == image_properties.c.image_id, image_properties.c.key == 'type')) ] and_stmt = and_(image_properties.c.image_id == None, images.c.type != None) sel = select([images], from_obj=from_stmt).where(and_stmt) image_records = conn.execute(sel).fetchall() property_insert = image_properties.insert() for record in image_records: conn.execute(property_insert, image_id=record.id, key='type', created_at=record.created_at, deleted=False, value=record.type) conn.close() disk_format = Column('disk_format', String(20)) disk_format.create(images) container_format = Column('container_format', String(20)) container_format.create(images) images.columns['type'].drop()
**** CubicPower OpenStack Study **** def downgrade(migrate_engine): meta = MetaData() meta.bind = migrate_engine # Steps to take, in this order: # 1) Add type column back to Image # 2) Move the existing type properties from ImageProperty into # Image.type # 3) Drop the disk_format and container_format columns in Image conn = migrate_engine.connect() images = get_images_table(meta) image_properties = get_image_properties_table(meta) type_col = Column('type', String(30)) type_col.create(images) sel = select([image_properties]).where(image_properties.c.key == 'type') type_property_records = conn.execute(sel).fetchall() for record in type_property_records: upd = images.update().where( images.c.id == record.image_id).values(type=record.value) conn.execute(upd) dlt = image_properties.delete().where( image_properties.c.image_id == record.image_id) conn.execute(dlt) conn.close() images.columns['disk_format'].drop() images.columns['container_format'].drop()
|