参考：https://blog.csdn.net/Jmilk/article/details/52484991
第一步：我们在nova\db\sqlalchemy\migrate_repo\versions添加文件349_thware.py，定义我们的新表
#--*-- coding:utf8--*--
from sqlalchemy import Boolean, Column, DateTime, Integer
from sqlalchemy import MetaData, String, Table
from oslo_log import log as logging
LOG = logging.getLogger(__name__)
TABLE_NAME='thware'
def define_tables(meta):
# 定义一个 Table 对象
thware = Table(
TABLE_NAME, meta,
Column('id', Integer),
Column('name', String(length=255)),
Column('vcs_ip', String(length=255), nullable=False),
Column('username', String(length=255), nullable=False),
Column('password', String(length=255), nullable=False),
mysql_engine='InnoDB')
return [thware]
def upgrade(migrate_engine):
meta = MetaData()
meta.bind = migrate_engine
# create all tables
# Take care on create order for those with FK dependencies
tables = define_tables(meta)
# 循环创建表列表
for table in tables:
try:
table.create()
except Exception:
LOG.info(_LE('Exception while creating table.'))
raise
def downgrade(migrate_engine):
meta = MetaData()
meta.bind = migrate_engine
tables = define_tables(meta)
tables.reverse()
for table in tables:
table.drop()
然后执行su -s /bin/sh -c "nova-manage db sync" nova
第二步：我们在文件Y:\usr\lib\python2.7\site-packages\nova\db\sqlalchemy\api.py添加我们的api：
@pick_context_manager_reader
def get_thware_info(context):
session = context.session
vcenters_info = session.query(models.Thware).all()
return vcenters_info
注意前面的装饰器，在我参考的博文中是直接通过以下语句获取session，在ocata版本中，用装饰器实现
session = get_session()
主要分为读数据库和更新数据库（还有异步操作的）：
@pick_context_manager_writer @pick_context_manager_reader
可以稍微看下代码实现:
def pick_context_manager_writer(f):
"""Decorator to use a writer db context manager.
The db context manager will be picked from the RequestContext.
Wrapped function must have a RequestContext in the arguments.
"""
@functools.wraps(f)
def wrapped(context, *args, **kwargs):
ctxt_mgr = get_context_manager(context)
with ctxt_mgr.writer.using(context):
return f(context, *args, **kwargs)
return wrapped
def pick_context_manager_reader(f):
"""Decorator to use a reader db context manager.
The db context manager will be picked from the RequestContext.
Wrapped function must have a RequestContext in the arguments.
"""
@functools.wraps(f)
def wrapped(context, *args, **kwargs):
ctxt_mgr = get_context_manager(context)
with ctxt_mgr.reader.using(context):
return f(context, *args, **kwargs)
return wrapped
第三步：在nova\db\api.py添加我们的api：
def get_thware_info(context):
return IMPL.get_thware_info(context)如此我们添加访问数据库新api完成。