SQLAlchemy和Falcon - 会话初始化

Question

我想知道创建一个用于猎鹰的范围会话的最佳位置.

从阅读flask-sqlalchemy代码,它在一个圆形的方式,做这样的事情:

from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker

try:
    from greenlet import get_current as get_ident
except ImportError:
    try:
        from thread import get_ident
    except ImportError:
        from _thread import get_ident

connection_uri = 'postgresql://postgres:@localhost:5432/db'
engine = create_engine(connection_uri)
session_factory = sessionmaker(bind=engine)
session_cls = scoped_session(session_factory, scopefunc=get_ident)
session = session_cls()

这会对猎鹰有用吗？get_ident使用gunicorn时,功能会"做正确的事"吗？

Answer 1

您可以使用中间件

例.

1. 创建engine,session_factory和scoped_session对象.

   from sqlalchemy import create_engine
   from sqlalchemy.orm import scoped_session
   from sqlalchemy.orm import sessionmaker
   
   import settings
   
   
   engine = create_engine(
       '{engine}://{username}:{password}@{host}:{port}/{db_name}'.format(
       **settings.POSTGRESQL
       )
   )
   
   session_factory = sessionmaker(bind=engine)
   Session = scoped_session(session_factory)
   

2. 创建中间件.

   class SQLAlchemySessionManager:
       """
       Create a scoped session for every request and close it when the request
       ends.
       """
   
       def __init__(self, Session):
           self.Session = Session
   
       def process_resource(self, req, resp, resource, params):
           resource.session = self.Session()
   
       def process_response(self, req, resp, resource, req_succeeded):
           if hasattr(resource, 'session'):
               Session.remove()
   

3. 注册中间件.

   import falcon
   
   
   app = falcon.API(middleware=[
       SQLAlchemySessionManager(Session),
   ])
   

4. 每个请求都可以访问会话.

   import falcon
   
   
   class MyAPI:
   
       def on_get(self, req, resp):
           # You can access self.session here
           # self.session.add(foo)
           # self.session.commit()