python - 如何验证 SqlAlchemy 引擎对象

Question

我可以使用无效的用户名、密码或地址声明 engine 对象，并且不会出现异常或错误:

from sqlalchemy import create_engine
engine = create_engine('mysql://nouser:nopassword@123.456.789')
print engine

它打印喜欢它是一个有效的引擎对象:

Engine(mysql://nouser:***@123.456.789)

验证(检查) engine 对象是否有效或它是否“可连接”到数据库的常用方法是什么？

Answer 1

问题:如何验证引擎对象是否“可连接”？

从( DOCs ):

Note that the Engine and its underlying Pool do not establish the first actual DBAPI connection until the Engine.connect() method is called, or an operation which is dependent on this method such as Engine.execute() is invoked. In this way, Engine and Pool can be said to have a lazy initialization behavior.

因此，要测试引擎对象是否“可连接”，需要显式调用 Engine.connect() 或尝试以其他方式使用引擎。

from sqlalchemy import create_engine
engine = create_engine('mysql://nouser:nopassword@123.456.789')
engine.connect()

会引发错误:

sqlalchemy.exc.OperationalError: (_mysql_exceptions.OperationalError) (2005, "Unknown MySQL server host '123.456.789' (0)")