Here is a tasty IBM Bluemix recipe with a dash of MongoDB and a pinch of Node.js. This posts shows the steps needed to perform basic CRUD (Create, Remove, Update & Delete) operations on the MongoDB database using REST APIs of PUT,GET, UPDATE & DELETE.
You can fork the code for the below app from Devops at mymongodb
The code can also be cloned from GitHub at mymongodb
For this, the first thing we need to do is to create a Webserver using Node.js as shown below
Webserver
require('http').createServer(function(req, res) {
if ( typeof mongodb !== 'undefined' && mongodb ) {
// Perform CRUD operations through REST APIs
if(req.method == 'POST') {
insert_records(req,res);
}
else if(req.method == 'GET') {
list_records(req,res);
}
else if(req.method == 'PUT') {
update_records(req,res);
}
else if(req.method == 'DELETE') {
delete_record(req,res);
}
} else {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.write("No MongoDB service instance is bound.\n");
res.end();
}
}).listen(port, host);
The Webserver users the port and host values obtained as shown above to wait for HTTP requests.
The REST API calls are handled by individual Node.js functions to perform the operations of insert, update, delete and select.
Insertions
The code for insertions is shown below. For this a set of 5 documents are created and then inserted using Node.js
var insert_records = function(req, res) {
var MongoClient = require('mongodb').MongoClient;
// Connect to the db
MongoClient.connect (mongo.url, function(err, db) {
//Create a collection test
var collection = db.collection('books', function(err, collection) {
//Create a set of documents to insert
var book1 = { book: "The Firm", author: "John Grisham", qty: 3 };
var book2 = { book: "Foundation", author: "Isaac Asimov", qty: 5 };
collection.remove(mycallback);
//Insert the books
console.log("Insert the books");
collection.insert(book1,function(err,result){});
collection.insert(book2, {w:1}, function(err, result) {
});
collection.insert(book5, {w:1}, function(err, result) {});
console.log('Inserted 5 books');
}); //var collection
}); // End MongoClient.connect
}; // End insert_records
Updating documents in Mongodb
For update 2 documents are changed as shown below
var update_records = function(req, res) {
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect (mongo.url, function(err, db) {
// Update
var collection = db.collection('books', function(err, collection) {
collection.update({book:"Fountainhead"},{$set:{qty:2}}, {w:1},function(err,result) {});
collection.update({book:"Animal Farm"},{$set:{author:"George Orwell"}}, {w:1},function(err,result) {});
console.log("Updated 2 books");
}); // var collection
}); //End MongoClient.connect
}; //End update-records
Deletions
The delete functions requires a callback method which is included
var delete_record = function(req, res) {
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect (mongo.url, function(err, db) {
//Deleting documents
var collection = db.collection(‘books’, function(err, collection) {
collection.remove({book:”Foundation”},mycallback);
collection.remove({book:”The Da Vinci Code”},{w:1},mycallback);
console.log(‘Deleted 2 books’);
});
}); //End MongoClient.connect
}; //End delete-records
Retrieving documents
To retrieve documents the collection.find.stream() method is used as below
var list_records = function(req, res) {
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect (mongo.url, function(err, db) {
//Retrieve documents
var collection = db.collection('books', function(err, collection) {
var stream = collection.find().stream();
console.log("Printing values...");
res.writeHead(200, {'Content-Type': 'text/plain'});
stream.on('error', function (err) {
console.error(err.stack)
});
stream.on(“data”, function(item) {
console.log(item);
res.write(JSON.stringify(item) + “\n”);
});
stream.on(“end”, function() {
console.log(“End”);
res.end();
});
}); //var collection
}); //End MongoClient.connect
The connection between the Node.js & Webserver and the MongoDB is setup using the VCAP_SERVICES as follows
if (process.env.VCAP_SERVICES) {
var env = JSON.parse(process.env.VCAP_SERVICES);
if (env['mongodb-2.2']) {
var mongo = env['mongodb-2.2'][0]['credentials'];
}
} else {
var mongo = {
"username" : "user1",
"password" : "secret",
"url" : "mongodb://user1:secret@localhost:27017/test"
}
}
To get started you can fork the code for the above Bluemix- MongoDB app from Devops from mymongodb
The code can also be cloned from GitHub at mymongodb
After you have forked the code you can clone the code into a local directory on your machine.
Now use the ‘cf’ command to push the code onto IBM Bluemix as shown. In my case I named the app as mymongodb01
cf login -a https://api.ng.bluemix.net
cf push mymongodb01 -p . -m 512M
cf create-service mongodb 100 mongodb
cf bind-service mymongodb01 mongodb
Instead of the last 2 steps you can also use the Add-service in Bluemix dashboard to add the MongoDB service. (Note: You will have to check Experimental at the top and you will see the service under Data Management.) After the MongoDB service is added check if your app is running in the Bluemix dashboard
If the app is running you can check the CRUD operations on MongoDB using the SureUtils-REST API client extension to Chrome.
The CRUD operations performed are shown below
1.POST + GET
Here 5 documents are inserted in the MongoDB and then displayed subsequently
2.UPDATE + GET
Here 2 records are updated – The quantity of the book ‘Fountainhead’ is set to 2 and the author of ‘Animal Farm’ is set to George Orwell
3.DELETE + GET
In this set 2 book are deleted and the result is displayed
If all things went well you should be able to see the app running.
You can also get the output o the console.login Files and Logs in the Bluemix dashboard.
Important tip: While executing the Buemix app if you run into problems and you app crashes with the “Health decreased” for your app and its colour turning red you can use the recent history of ‘cf” command to debug your problem
PS C:\Users\IBM_ADMIN\git\mymongodb> cf logs mymongodb01 –recent
Connected, dumping recent logs for app mymongodb01 in org tvganesh.85@gmail.com / space dev as tvganesh.85@gmail.com…
…….
…….
2014-07-27T11:34:26.45+0530 [App/0] OUT We are connected to DB
2014-07-27T11:34:26.46+0530 [App/0] OUT Updated 2 books
2014-07-27T11:34:31.17+0530 [App/0] OUT We are connected to DB
2014-07-27T11:34:31.17+0530 [App/0] OUT Updated 2 books
2014-07-27T11:34:31.18+0530 [RTR] OUT mymongodb01.mybluemix.net - [27/07/2014:06:04:31 +0000] "PUT / HTTP/1.1" 200 1
7 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36" 75
.126.70.43:19986 vcap_request_id:4fa831610b6e79455d0257581a51014e response_time:0.009122768 app_id:ed49744f-1a29-4e3f-9e
1c-8b45e85c3310
2014-07-27T11:35:02.75+0530 [App/0] ERR
2014-07-27T11:35:02.75+0530 [App/0] ERR /home/vcap/app/app.js:95
2014-07-27T11:35:02.75+0530 [App/0] ERR MongoClient.connect (mongo.url, function(err, db) {
2014-07-27T11:35:02.75+0530 [App/0] ERR ^
2014-07-27T11:35:02.75+0530 [App/0] ERR ReferenceError: MongoClient is not defined
2014-07-27T11:35:02.75+0530 [App/0] ERR at delete_record (/home/vcap/app/app.js:95:2)
2014-07-27T11:35:02.75+0530 [App/0] ERR at Server.<anonymous> (/home/vcap/app/app.js:165:12)
2014-07-27T11:35:02.75+0530 [App/0] ERR at Server.emit (events.js:98:17)
2014-07-27T11:35:02.75+0530 [App/0] ERR at HTTPParser.parser.onIncoming (http.js:2108:12)
2014-07-27T11:35:02.75+0530 [App/0] ERR at HTTPParser.parserOnHeadersComplete [as onHeadersComplete] (http.js:121:
23)
2014-07-27T11:35:02.75+0530 [App/0] ERR at Socket.socket.ondata (http.js:1966:22)
2014-07-27T11:35:02.75+0530 [App/0] ERR at TCP.onread (net.js:527:27)
2014-07-27T11:35:02.80+0530 [RTR] OUT mymongodb01.mybluemix.net - [27/07/2014:06:05:02 +0000] "DELETE / HTTP/1.1" Mi
ssingResponseStatusCode 0 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.19
Happy cooking with Bluemix, MongoDB & Node.js!
Disclaimer: This article represents the author’s viewpoint only and doesn’t necessarily represent IBM’s positions, strategies or opinions
See also
1. Brewing a potion with Bluemix, PostgreSQL & Node.js in the cloud
2. Spicing up IBM Bluemix with MongoDB and NodeExpress
3. A Cloud Medley with IBM’s Bluemix, Cloudant and Node.js
4. Rock N’ Roll with Bluemix, Cloudant & NodeExpress
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Giga thoughts ... 
Nice post. I learn something new and challenging on sites
I stumbleupon everyday. It’s always useful to read through content from other authors and use something from their
sites.
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One question, do you know how to explore the db using “Mongo Management Studio”? It keeps rejecting my connection!
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