Please comment the changes!

Your job is to save each customers feedback to a local MongoDB with the following settings:

The following code should be added to the app.js below

Database URL: mongodb://127.0.0.1:27017/local

Database name: local(You can deduce from the above URL.)

Collection name: feedback

Document format: {date: 7/16/2016, content: This is a test for customer feedback.}

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app.js

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/** app.js This is a simple web site that hosts a fake Wake Tech Credit Union web site. It saves customer feedback in a MongoDB. */  var express = require('express'); var fs = require('fs'); var MongoClient = require('mongodb').MongoClient; var collection; // programmer defined function to return customer feedback log as an html to the browser. function createHTMLReturn(docs, res) { var htmlText = ""; for (var i = 0; i < docs.length; i++){ var doc = docs[i]; htmlText += ""; } htmlText += "
Date
Feedback
" + doc.date + "
" + doc.content + "
"; res.send(htmlText); } /**  * Define the sample application.  */ var SampleApp = function() { // Scope. var self = this; /* ================================================================ */ /* Helper functions. */ /* ================================================================ */ /**  * Set up server IP address and port # using env variables/defaults.  */  self.setupVariables = function() { // Set the environment variables we need. //self.ipaddress = process.env.IP; //self.port = process.env.PORT || 5000; //if (typeof self.ipaddress === "undefined") { // self.ipaddress = "127.0.0.1"; //}; }; /**  * Populate the cache.  */  self.populateCache = function() { if (typeof self.zcache === "undefined") { self.zcache = { 'index.html': '' }; } // Local cache for static content. self.zcache['index.html'] = fs.readFileSync('./index.html'); }; /**  * Retrieve entry (content) from cache.  * @param {string} key Key identifying content to retrieve from cache.  */  self.cache_get = function(key) { return self.zcache[key]; }; /**  * terminator === the termination handler  * Terminate server on receipt of the specified signal.  * @param {string} sig Signal to terminate on.  */  self.terminator = function(sig){ if (typeof sig === "string") { console.log('%s: Received %s - terminating sample app ...', Date(Date.now()), sig); process.exit(1); } console.log('%s: Node server stopped.', Date(Date.now()) ); }; /**  * Setup termination handlers (for exit and a list of signals).  */  self.setupTerminationHandlers = function(){ // Process on exit and signals. process.on('exit', function() { self.terminator(); }); // Removed 'SIGPIPE' from the list - bugz 852598. ['SIGHUP', 'SIGINT', 'SIGQUIT', 'SIGILL', 'SIGTRAP', 'SIGABRT', 'SIGBUS', 'SIGFPE', 'SIGUSR1', 'SIGSEGV', 'SIGUSR2', 'SIGTERM' ].forEach(function(element, index, array) { process.on(element, function() { self.terminator(element); }); }); }; /* ================================================================ */ /* App server functions (main app logic here). */ /* ================================================================ */ /**  * Create the routing table entries + handlers for the application.  */  self.createRoutes = function() { self.routes = { }; self.routes['/feedback'] = function(req, res) { console.log("-- Received a customer feedback: [" + req.body.feedback + "]"); // Save to MongoDB -- to be completed by the student // A sample feedback document looks like this: // { "date": "7/16/2016", "content": "This is a test for customer feedback" } // Hint: The database url is: 'mongodb://127.0.0.1:27017/local' // The collection name is 'feedback' // Remember to close the connection by calling 'db.close();' // Troubleshooting: If you get database error, make sure the following is done: // 1. Your mongodb is installed and is running. // 2. You have created a collection named 'feedback' in the default database called 'local'. // The commands to do it is: // use local // db.createCollection('feedback') res.send("Thanks for your feedback!"); }; self.routes['/log'] = function(req, res) { // Retrieve all feedback documents from MongoDB MongoClient.connect('mongodb://127.0.0.1:27017/local', function (err, db){ if (err) throw err; console.log('connected to mongodb://127.0.0.1:27017/local'); db.collection('feedback').find().toArray(function(err, docs) { createHTMLReturn(docs, res); }); db.close(); }); }; self.routes['/'] = function(req, res) { res.setHeader('Content-Type', 'text/html'); res.send(self.cache_get('index.html') ); }; }; /**  * Initialize the server (express) and create the routes and register  * the handlers.  */  self.initializeServer = function() { self.createRoutes(); //self.app = express.createServer(); self.app = express(); self.app.set('port', process.env.PORT || 3333); self.app.set('ip', process.env.IP || "127.0.0.1"); self.app.use(express.static(__dirname)); //self.app.use(express.bodyParser()); self.app.use(express.json()); self.app.use(express.urlencoded()); // Add handlers for the app (from the routes). for (var r in self.routes) { self.app.get(r, self.routes[r]); // maps the HTTP GET request self.app.post(r, self.routes[r]); // maps the HTTP POST request } }; /**  * Initializes the sample application.  */  self.initialize = function() { self.setupVariables(); self.populateCache(); self.setupTerminationHandlers(); // Create the express server and routes. self.initializeServer(); }; /**  * Start the server (starts up the sample application).  */  self.start = function() { // Start the app on the specific interface (and port). self.app.listen(self.app.get('port'), function() { console.log('%s: Node server started on %s:%d ...', Date(Date.now() ), self.app.get('ip'), self.app.get('port')); }); }; }; /* Sample Application. */ /**  * main(): Main code.  */ var zapp = new SampleApp(); zapp.initialize(); zapp.start();