node.js - Unable to obtain session in express router

Question

I use app.post(); directly in app.js to get the session.
But I can’t get the session when I use router.post(); in the router.
What’s going on? Seek the guidance of the great God

As shown

Display seesion cannot be obtained

Answer 1

Is it a matter of order? The session middleware needs to be before all routers

Answer 2

It seems that your second router is not associated with the app,
so the one behind you does not enter the session middleware, causing the session to be unavailable.

Answer 3

app.use('/xxx', router);

Is this missing?