title: How to update session data if already session created express-session
body: <p>I am creating session using <code>express-session</code> module. Session is creating and saving in <code>session</code> collection succesfully and working fine.
  Below is <code>express-session</code> configuration.</p>
  
  <pre><code>var session = expressSession({
      saveUninitialized : false,
      resave : true,
      secret :  'asfndu123nisdf2u34',
      cookie: {
          path: "/",
          maxAge: appConfig.maxAge
      },
      name : appConfig.sessionKey,
      store : appConfig.mongoStore
  });
  </code></pre>
  
  <p>login code snippt:</p>
  
  <pre><code>login: function(req, res, next){
               userModel.findOne({email:req.body.email}, function(err, user){
               if(user.password !== req.body.password){
                  return res.json({"Wrong Credentials"});
               }else{
                  req.session.user = user;
                  req.session.save();
               }
               })
          }
  </code></pre>
  
  <p>If I am loging in a browser then its creating a document in <code>session</code> collection. and if with same credential again login in another browser then also its creating a new document in <code>session</code> collection.</p>
  
  <p>Is it right approach to create a new document(row) in session collection everytime? If not then please let me know how I can check and update the session if already loggedin.</p>
  
  <p>Thanks. </p>