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"""fix identifier map fk

Revision ID: 56893333aa52
Revises: kilo
Create Date: 2015-06-11 12:09:01.263253

"""

from alembic import op
import sqlalchemy as sa
from sqlalchemy.sql import column
from sqlalchemy.sql import expression as expr
from sqlalchemy.sql import func
from sqlalchemy.sql import table

from neutron.db import migration
from neutron.db.migration import cli


# revision identifiers, used by Alembic.
revision = '56893333aa52'
down_revision = 'kilo'
branch_labels = (cli.CONTRACT_BRANCH,)


def upgrade():
    # re-size existing data if necessary
    identifier_map = table('cisco_csr_identifier_map',
                           column('ipsec_site_conn_id', sa.String(36)))
    ipsec_site_conn_id = identifier_map.columns['ipsec_site_conn_id']

    op.execute(identifier_map.update(values={
        ipsec_site_conn_id: expr.case([(func.length(ipsec_site_conn_id) > 36,
                                      func.substr(ipsec_site_conn_id, 1, 36))],
                                      else_=ipsec_site_conn_id)}))

    # Need to drop foreign key constraint before mysql will allow changes

    with migration.remove_fks_from_table('cisco_csr_identifier_map'):
        op.alter_column(table_name='cisco_csr_identifier_map',
                        column_name='ipsec_site_conn_id',
                        type_=sa.String(36),
                        existing_nullable=False)
