app.post('/login', routes.dologin);

exports.dologin = function (req, res) {
res.locals.session = req.session;

var user = req.body.user;
db.authenticateUser(user.email, user.password, function     ( err, response) {
if (err) {
.......

.......
} else {
.......

........
}
});
};

var mongo = require('mongoskin'),
crypto = require('crypto');

module.exports = function (config) {

var USERS_COLLECTION = 'users',
ORDERS_COLLECTION = 'orders',
salt = 'supersecretkey',
db;

    authenticateUser: function (emailId, password,         callback) {
    db.collection(USERS_COLLECTION).count({email : emailId,         password: encryptPassword(password)}, function (err,         count) {
    if (err) {
console.log("error authenticating user: " + err);
callback(new Error(err));
} else if (count === 0) {
callback(new Error("emailid/password did not match"));
} else {
callback(null);
}
});
},
    }

var mongo = require('mongoskin'),
    crypto = require('crypto');

module.exports = function (config) {

    var USERS_COLLECTION = 'users',
        ORDERS_COLLECTION = 'orders',
        salt = 'supersecretkey',
        db = mongo.db('localhost:27017/yourdb');

    authenticateUser: function (emailId, password, callback) {

        db.collection(USERS_COLLECTION).count({
            email: emailId,
            password: encryptPassword(password)
        }, function (err, count) {
            if (err) {
                console.log("error authenticating user: " + err);
                callback(new Error(err));
            } else if (count === 0) {
                callback(new Error("emailid/password did not match"));
            } else {
                callback(null);
            }
        });
    },
}