30 Days of node
Day 12 : CRUD operations in mongodb



30 days of node - Nodejs tutorial series

  1. Day 1 - The Beginning
  2. Day 2 - File System in node.js
  3. Day 3 - Regular expressions in node.js
  4. Day 4 - Console module in node.js
  5. Day 5 - All about errors
  6. Day 6 - Array methods
  7. Day 7 - All about NPM
  8. Day 8 - Publishing package on NPM
  9. Day 9 - Crypto Module ( Hashing and HMAC)
  10. Day 10 - Crypto Module ( Encryption and Decryption )
  11. Day 11 - Express Framework
  12. Day 12 - CRUD in MongoDB using node.js
  13. Day 13 - Sign Up form in node.js
  14. Day 14 - Introduction to socket.io
  15. Day 15 - All about streams
  16. Day 16 - Zlib Module
  17. Day 17 - CRUD in MySQL using node.js
  18. Day 18 - Concepts of callbacks in node.js
  19. Day 19 - Query String in node.js
  20. Day 20 - Timers in node.js
  21. Day 21 - Buffers in node.js
  22. Day 22 - String Decoder Module in node.js
  23. Day 23 - Debugger module in node.js
  24. Day 24 - Child Processes in node.js
  25. Day 25 - Clusters in node.js
  26. Day 26 - OS module in node.js
  27. Day 27 - Assert module in node.js
  28. Day 28 - Getting Tweets using node.js
  29. Day 29 - Uploading file to dropbox using node.js
  30. Day 30 - Github API with node.js

What is MongoDb ?

Classified as a No SQL database , MongoDB is a scalable, open source, high performance , document-oriented database designed by keeping developers agility in mind. It is document-oriented which means that it does not store data in tables and rows as we would in relational databases like MySQL, In this we store data in JSON-like documents with dynamic schema.
Advantages :

  1. Dynamic schema : If we have an flexible schema then it is ideal for JSON-like documents as in MongoDB however it is difficult to implement it in a good manner in Relational databases.
  2. Scalability : MongoDB is highly scalable
  3. Cheap : Can be downloaded free of cost.

Prerequisites

  1. MongoDb : You can download it here .
  2. Node.js : You can download it here .
  3. NPM : It is already installed on your system when you installed node.js
  4. mongodb (npm package) : We can install it using the command given below : 
    											
>npm install mongodb

Establishing connection with db

The first step is to establish a connection between the mongodb database and our node.js application. 

								
//Including the required packages
var mongo = require('mongodb');
//Establishing the connection
var new_db = "mongodb://localhost:27017/demo_db"

Here ,
  • demo_db is the name of the db to be created
  • 27017 is the port number where mongodb is running.
  • localhost signifies that currently the db is running locally.

Now , We will establish the connection using the connect method. Connect() is an inbuilt method used to is an inbuilt method used to Creates a connection to a MongoDB instance and returns the reference to the database. It instantiates a new connection to the MongoDB instance running on the localhost interface and returns a reference to demo_db. Snippet for establishing connection using connect method is given below : 
								
//File Name is  : demo-db.js
//establishing the connection
mongo.connect(new_db ,(error , db) => {
	if (error){
		throw error;
	}
	console.log("Database demo_db created successfully");
	//To close the connection
	db.close();
});

We can run the above code using the following command : 
								
> node demo-db.js
Database demo_db created successfully

Congratulations , we successfully established a connection with mongodb using node.js

Insert/Create Operation in MongoDb

  1. insertOne() : insertOne() is an inbuilt method which is used to insert data in the mongoDb collection. Snippet for the following is given below : 
    								
//Name of the file  : insert-mongo.js
mongo.connect(new_db , function(error , db){
	if (error){
		throw error;
	}
	
	var data = { name : "rishabhio" , age : "25" , mobile : "1234567890" }
	
	db.collection("details").insertOne(data, (err , collection) => {
		if(err) throw err;
		console.log("Record inserted successfully");
		console.log(collection);
	});
});

    We can run the above code using the following command : 
    								
> node insert-mongo.js
>node insert_mongo_nodejs.js
Record inserted successfully
{ result: { ok: 1, n: 1 },
  connection: null,
  message: undefined,
  ops:
   [ { name: 'rishabhio',
       age: '25',
       mobile: '1234567890',
       _id: 597073b2c6f60f5b3c23a1a5 } ],
  insertedCount: 1,
  insertedId: 597073b2c6f60f5b3c23a1a5 
}

Read Operation in MongoDb

  1. findOne() : findOne() is an inbuilt method which is used to Read the first occurance of the data from the mongoDb collection. 
    											
//name of the file : read-one.js
mongo.connect(new_db , function(error , db){
	if (error){
		throw error;
	}
	//findOne() reads the first occurance of any data from the database.
	db.collection("details").findOne({}, (err , collection) => {
		if(err) throw err;
		console.log("Record Read successfully");
		console.log(collection);
		db.close();
	});
});

    We can run the above code using the following command : 
    											
> node read-one.js
Record Read successfully
{ name: 'Nodejsera',
  age: '23',
  mobile: '9876543210',
  _id: 59706a56a4f6761e3cc22c98 }

  2. find() : find() is an inbuilt method which is used to Read all data from the mongoDb collection. 
    											
//name of the file : read-all.js
mongo.connect(new_db , function(error , db){
	if (error){
		throw error;
	}
	
	//Read All the data from the "details" collection.
	db.collection("details").find({}).toArray( (err , collection) => {
		if(err) throw err;
		console.log("Record Read successfully");
		console.log(collection);
		db.close();
	});
});

    We can run the above code using the following command : 
    											
> node read-all.js
Record Read successfully
[ { name: 'Nodejsera',
    age: '23',
    mobile: '9876543210',
    _id: 59706a56a4f6761e3cc22c98 },
  { name: 'rishabhio',
    age: '25',
    mobile: '1234567890',
    _id: 59706c3771da112bd8b922dc },
  { name: 'rishabhio',
    age: '25',
    mobile: '1234567890',
    _id: 597073b2c6f60f5b3c23a1a5 } ]

Update data in an document

  1. updateOne() : updateOne() is an inbuilt method of mongodb which is used to search the first occurance of the data and update it. 
    											
//name of the file : update-one.js
mongo.connect(new_db ,(error , db) => {
	if (error){
		throw error;
	}
	//Query parameter is used to search the collection.
	var query = { name : "rishabhio" };
	//And When the query matches the data in the DB , "data" parameter is used to update the value.
	var data = { name : "nodejsera.com" , mobile : "1234567890" }
	//Accessing the collection using nodejs
	db.collection("details").updateOne(query , data, (err , collection) => {
		if(err) throw err;
		console.log("Record updated successfully");
		console.log(collection);
	});
});

    We can run the above code using the following command : 
    											
> node update-one.js
Record updated successfully
{ result: { ok: 1, n: 1, nModified: 1 },
  connection: null,
  message: undefined,
  modifiedCount: 1,
  upsertedId: null,
  upsertedCount: 0,
  matchedCount: 1 }

  2. updateMany() : updateMany() is the inbuilt method of mongodb which is used to search for the given query and update all its occurances. 
    											
//name of the file : update-all.js
mongo.connect(new_db ,(error , db) => {
	if (error){
		throw error;
	}
	
	//query store the search condition
	var query = { age : {$gt : "22" } };
	//data stores the updated value
	var data = { $set : {age : "above 22" } }
	//CREATING A COLLECTION IN MONGODB USING NODE.JS
	db.collection("details").updateMany(query , data, (err , collection) => {
		if(err) throw err;
		console.log(collection.result.nModified + " Record(s) updated successfully");	//It will console the number of rows updated
		console.log(collection);
		db.close();
	});
});

    We can run the above code using the following command : 
    											
> node update-all.js
node updateMany-mongodb-nodejs.js
3 Record(s) updated successfully
{ 	result: 
		{ 
			ok: 1,
			n: 3,
			nModified: 3 
		},
	connection: null,
	message: undefined,
	modifiedCount: 3,
	upsertedId: null,
	upsertedCount: 0,
	matchedCount: 3 
 }

Delete a document

  1. deleteOne() : deleteOne() is the inbuilt method of mongodb which is used to delete the first occurance of the data provided in the search query. 
    											
//name of the file : delete-one.js
mongo.connect(new_db ,(error , db) => {
	if (error){
		throw error;
	}
	//query stores the search condition	
	var query = { age : "above 22" };
	
	//Accessing a COLLECTION IN MONGODB USING NODE.JS
	db.collection("details").deleteOne(query , (err , collection) => {
		if(err) throw err;
		console.log(collection.result.n + " Record(s) deleted successfully");
		console.log(collection);
		db.close();
	});
});

    We can run the above code using the following command : 
    											
> node delete-one.js
1 Record(s) deleted successfully
{ 
	result: 
		{ 
			ok: 1,
			n: 1
		},
	connection: null,
	message: undefined,
	deletedCount: 1 
}

  2. deleteMany() : deleteMany() is the inbuilt method of mongodb which is used to delete all the occurances of the data provided in the search query. 
    											
//name of the file : delete-all.js
mongo.connect(new_db ,(error , db) => {
	if (error){
		throw error;
	}
	
	//Search query for deletion
	var query = { age : "above 22" };
	
	//Accessing the collection
	db.collection("details").deleteMany(query , (err , collection) => {
		if(err) throw err;
		console.log(collection.result.n + " Record(s) deleted successfully");
		console.log(collection);
		db.close();
	});
});

    We can run the above code using the following command : 
    											
> node delete-all.js
2 Record(s) deleted successfully
{ 
	result: 
		{ 
			ok: 1,
			n: 2
		},
	connection: null,
	message: undefined,
	deletedCount: 2 
}

Summary

In this chapter of 30 days of node tutorial series, we learned about how we can establish a connection with a MongoDb database using node.js and perfrom the basic create, read, update and delete operations.