async = require('async')

var mongoose = require('mongoose'), async = require('async');

mongoose.connect('localhost', 'learn-mongoose');

var User = mongoose.model('User', {name: String});

async.series([
    function (done) {
        // remove User collection if exist
        User.remove(done);
    },

    function(done) {
        // re-create a collection with 2 users 'Mr One', 'Mr Two'
        User.create([{name: 'Mr One'}, {name: 'Mr Two'}], done);
    },

    function(done) {
        // upperCase user.name
        User.find(function(err, users) {
            async.each(users, function(user, callback) {
                user.name = user.name.toUpperCase();
                user.save(callback);
            }, done); // done is call when all users are save!!!!
        });
    },
    function(done) {
        // print result
        User.find(function(err, users) {
            console.log(users);
            done();
        });
    },
], function allTaskCompleted() {
    console.log('done');
    mongoose.disconnect();
});