如何记录 sqlalchemy 中返回的 SQL 语句和行以帮助调试？

Question

如何配置

sqlalchemy

来记录它向数据库服务器发出的 SQL 语句，并记录从这些语句返回的行？这对于调试很有用。

Answer 1

选项 1：将

sqlalchemy.engine

记录器日志级别设置为

logging.INFO

或

logging.DEBUG

: 例如，

像这样配置：

import logging
logging.basicConfig()
logger = logging.getLogger('sqlalchemy.engine')
logger.setLevel(logging.DEBUG)
session.query(User).all()

交互式使用：

>>> import logging
>>> logging.basicConfig()
>>> logger = logging.getLogger('sqlalchemy.engine')
>>> logger.setLevel(logging.DEBUG)
>>> session.query(User).all()
2015-01-02 11:54:25,854 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2015-01-02 11:54:25,856 INFO sqlalchemy.engine.base.Engine SELECT users.id AS users_id, users.name AS users_name
FROM users
2015-01-02 11:54:25,857 INFO sqlalchemy.engine.base.Engine {}
2015-01-02 11:54:25,858 DEBUG sqlalchemy.engine.base.Engine Col ('users_id', 'users_name')
2015-01-02 11:54:25,860 DEBUG sqlalchemy.engine.base.Engine Row (1, u'Alice')
2015-01-02 11:54:25,860 DEBUG sqlalchemy.engine.base.Engine Row (2, u'Bob')

参考：配置日志记录

选项 2：调用

echo

时使用

sqlalchemy.create_engine()

参数：

例如，

>>> from sqlalchemy import create_engine
>>> from sqlalchemy.orm import sessionmaker
>>> engine = create_engine('postgres://postgres_user:my_password@localhost/my_db',
...                        echo="debug")
>>> Session = sessionmaker(bind=engine)
>>> session = Session()
>>> users = session.query(User).all()
2015-01-02 11:54:25,854 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2015-01-02 11:54:25,856 INFO sqlalchemy.engine.base.Engine SELECT users.id AS users_id, users.name AS users_name
FROM users
2015-01-02 11:54:25,857 INFO sqlalchemy.engine.base.Engine {}
2015-01-02 11:54:25,858 DEBUG sqlalchemy.engine.base.Engine Col ('users_id', 'users_name')
2015-01-02 11:54:25,860 DEBUG sqlalchemy.engine.base.Engine Row (1, u'Alice')
2015-01-02 11:54:25,860 DEBUG sqlalchemy.engine.base.Engine Row (2, u'Bob')

根据 sqlalchemy 文档：

*sqlalchemy。create_engine （*args，**kwargs）
...
echo=False – 如果为 True，引擎会将所有语句及其参数列表的 repr() 记录到引擎记录器中，默认为 sys.stdout。可以随时修改Engine的echo属性来打开和关闭日志记录。如果设置为字符串“debug”，结果行也将打印到标准输出。