var RedisStore = require('connect-redis')(express);
app.use(express.bodyParser());
app.use(express.cookieParser());
app.use(express.session(
  { secret: "change_me", store: new RedisStore })
);

app.post('/add-to-cart', function(req, res){
  // Perhaps we posted several items with a form
  // (use the bodyParser() middleware for this)
  var items = req.body.items;
  req.session.items = items;
  res.redirect('back');
});