How to check session in Node.js Express?

Question

I try to check if session in Express 4 is exist:

if(req.session.user == undefined) {}

It gives me error:

 Cannot read property          


        

Answer 1

You can't just create a session without any middleware (Im assuming this is what you've tried).

Read up on the express-session middleware docs, found here:

https://github.com/expressjs/session

Basic implementation example:

Create a session:

app.use(session({
  genid: function(req) {
    return genuuid() // use UUIDs for session IDs
  },
  secret: 'keyboard cat'
}))

To read a session:

// Use the session middleware
app.use(session({ secret: 'keyboard cat', cookie: { maxAge: 60000 }}))

// Access the session as req.session

app.get('/', function(req, res, next) {
  var sess = req.session
  if (sess.views) {
    sess.views++
    res.setHeader('Content-Type', 'text/html')
    res.write('
views: ' + sess.views + '
')
    res.write('
expires in: ' + (sess.cookie.maxAge / 1000) + 's
')
    res.end()
  } else {
    sess.views = 1
    res.end('welcome to the session demo. refresh!')
  }
})

There are a number of tutorials you can find online, e.g:

https://www.thepolyglotdeveloper.com/2015/01/session-management-expressjs-web-application/