node.js - app.use的参数，get不到

Question

不知道怎么表达，反正就是报错了

Answer 1

Obviously your username is not defined
Try adding an if judgment to your second middleware

Answer 2

Just take it directly when you use it,

Answer 3

The two usernames are in different scopes, of course they are undefined...

Answer 4

These are the variables of two methods. The second one cannot refer to the username in the first method. Use req.session.username again and get it once.