db.js

var mongoose = require('mongoose'),
    Schema = mongoose.Schema;

module.exports = function () {
 mongoose.connect('mongodb://localhost/test',
    function(err) {
        if (err) { throw err; }
    }
 );
};

var User = new Schema({
    username: {type: String, index: { unique: true }},
    mdp: String
});

module.exports = mongoose.model('User', User);