Nodejs/Express Session - Error: Can't set headers after they are sent - express-session

Question

I am getting the below error while trying to use express session with a simple nodejs sample app.
When "resave" is set to true the below error appears, however when the same is set to false, there is no error.
GET / 304 13.380 ms - - Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:344:11)
at ServerResponse.header
(/Volumes/SURESH/GSKLabs/NodeApp/node_modules/express/lib/response.js:718:10)
at ServerResponse.contentType
(/Volumes/SURESH/GSKLabs/NodeApp/node_modules/express/lib/response.js:551:15)
at ServerResponse.send
(/Volumes/SURESH/GSKLabs/NodeApp/node_modules/express/lib/response.js:138:14)
at done
(/Volumes/SURESH/GSKLabs/NodeApp/node_modules/express/lib/response.js:957:10)
Below is the code app.js
var express = require('express');
var session = require('express-session');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var mongojs = require('mongojs');
var mongoStore = require('connect-mongo')(session);
var db = mongojs('mongodb://localhost:27017/checker', ['sessions']);
var routes = require('./routes/index');
var app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');
var sessionStore = new mongoStore({
db: db,
})
// Session details
app.use(session({
secret: 'check first',
name: {secure: true, maxAge: 60000},
store: sessionStore, // connect-mongo session store
proxy: true,
resave: true,
saveUninitialized: true
}));
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', routes);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handlers
// development error handler
// will print stacktrace/Volumes/SURESH/GSKLabs/NodeApp/node_modules/express/lib/router/index.js:310:13
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: err
});
});
}
// production error handler
// no stacktraces leaked to user
app.use(function (err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
module.exports = app;
routes/index.js
var express = require('express');
var router = express.Router();
/* GET home page. */
router.get('/', function(req, res, next) {
res.render('index', { title: 'Express' });
});
module.exports = router;
package.json
{
"name": "NodeApp",
"version": "0.0.0",
"private": true,
"scripts": {
"start": "node ./bin/www"
},
"dependencies": {
"body-parser": "~1.15.1",
"connect-mongo": "^1.3.2",
"cookie-parser": "~1.4.3",
"debug": "~2.2.0",
"ejs": "~2.4.1",
"express": "~4.13.4",
"express-session": "^1.14.1",
"mongojs": "^2.4.0",
"morgan": "~1.7.0",
"serve-favicon": "~2.3.0"
}
}
As per my understanding, since the resave:true, express session trying to set the cookie after the response is already sent. Cannot change to resave:false, as it needs to be "true" for using rolling option in express session.
Any help how to solve this error in the above sample code. Thanks.