Global before and after event handlers

[wbobeirne]

Is your feature request related to a problem? Please describe.

We're using flask-sqlalchemy as well as flask-socketio, and are running into a problem where we have some lingering db sessions. These are a little tricky to track down where you may have forgotten to commit / rollback and close a session, so it'd be easiest if we could have a handler for after every event.

Likewise, it'd be nice to add some logging for every event we receive.

Describe the solution you'd like

Similar to flask's @app.before_request & @app.after_request, it'd be nice if there was a @flask_socketio.before_event and @flask_socketio.after_event that fired for every event the socket gets.

Describe alternatives you've considered

Manually adding function calls to the beginning and end of every on. Doable, but unenforceable and prone to making a mistake.

[miguelgrinberg]

You can use a class-based namespace for this. Something like this:

class MyNamespace(Namespace):
    def on_event_one(self, data):
        pass

    def on_event_two(self, data):
        pass

    def trigger_event(self, event, *args):  # this is called for all events
        super().trigger_event(event, *args)  # this will dispatch the event to the proper method
        db.session.remove()  # cleanup code