exports.isLocalAuthenticated = function(req, res, next) {
    passport.authenticate('local', function(err, user, info) {
        if (err) { return next(err); } //error exception

        // user will be set to false, if not authenticated
        if (!user) {
            res.status(401).json(info); //info contains the error message
        } else {
            // if user authenticated maintain the session
            req.logIn(user, function() {
                // do whatever here on successful login
            })
        }    
    })(req, res, next);
}