Henry Gessau 8be88da5c1 Base DB: rehome model_base
This change 'rehomes' model_base.py from neutron.

This is not quite a verbatim copy due to the following differences:

 - The field sizes for columns are replaced with the new constants
   from neutron_lib/db/constants.py

 - The tenant_id deprecation message is adjusted slightly.

 - The StandardAttribute table is not included.

We also add some base classes and fixtures for DB unit tests.

Partially Implements: Blueprint neutron-lib

Change-Id: I2087c6f5f66154cdaa4d8fa3d86f5e493f1d24d9
2016-08-19 08:47:37 -04:00

47 lines
1.4 KiB
Python

# 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.
"""
TEMPORARY: use the old EngineFacade and lazy init.
TODO(HenryG): replace this file with the new db/api.py from neutron.
"""
from oslo_config import cfg
from oslo_db.sqlalchemy import session
_FACADE = None
def _create_facade_lazily():
global _FACADE
# NOTE: This is going to change with bug 1520719
if _FACADE is None:
_FACADE = session.EngineFacade.from_config(cfg.CONF, sqlite_fk=True)
return _FACADE
def get_engine():
"""Helper method to grab engine."""
facade = _create_facade_lazily()
return facade.get_engine()
def get_session(autocommit=True, expire_on_commit=False, use_slave=False):
"""Helper method to grab session."""
facade = _create_facade_lazily()
return facade.get_session(autocommit=autocommit,
expire_on_commit=expire_on_commit,
use_slave=use_slave)