使用sqlalchemy设置值后如何运行“设置”事件侦听器

Question

I have an event-listener in an sqlalchemy-project, which i want to run after the target and one other value have been saved.

@event.listens_for(Component.name, 'set')
def do_things(target, value, oldvalue, initiator):
    print(target.someOtherValue)

now target.someOtherValue only sometimes holds the new value(indicating a timing issue?).

How can I make sure to always run the function after the new values are saved?

Answer 1

Had a similar problem but resolved it with the 'before_update' event. Hope it works for you too.

@event.listens_for(SomeClass, 'before_update')
def receive_before_update(mapper, connection, target):
"listen for the 'before_update' event"

# ... (event handling logic) ...

NB: Make sure not to add .name on your SomeClass object. Use the target.yourclassproperty to refer to properties specific to a particular class.

Read more about Sqlalchemy's Mapper Events