OpenStack Study: 041_add_remaining_uses_count_to_trusts.py

**** CubicPower OpenStack Study ****

def downgrade_trust_table_with_column_drop(meta, migrate_engine):

    trust_table = sqlalchemy.Table('trust', meta, autoload=True)

    # delete trusts with a limited use count, we are downgrading so uses

    # will not be tracked anymore.

    d = trust_table.delete(trust_table.c.remaining_uses >= 0)

    d.execute()

    trust_table.drop_column('remaining_uses')

**** CubicPower OpenStack Study ****

def upgrade_trust_table(meta, migrate_engine):

    trust_table = sqlalchemy.Table('trust', meta, autoload=True)

    trust_table.create_column(sqlalchemy.Column('remaining_uses',

                              sqlalchemy.Integer(),

                              nullable=True))

**** CubicPower OpenStack Study ****

def upgrade(migrate_engine):

    meta = sqlalchemy.MetaData()

    meta.bind = migrate_engine

    upgrade_trust_table(meta, migrate_engine)

**** CubicPower OpenStack Study ****

def downgrade(migrate_engine):

    meta = sqlalchemy.MetaData()

    meta.bind = migrate_engine

    downgrade_trust_table_with_column_drop(meta, migrate_engine)