[MongoDb][Node.js] Create-Retrieve-Update-Delete (CRUD) in mongodb

01_insert.js

/**
 * A Simple demonstration of documents inserts against mongodb replica set
 */

var MongoClient = require('mongodb').MongoClient,
	assert=require('assert');
var connection_string = "mongodb://127.0.0.1:27017,127.0.0.1:27018,127.0.0.1:27019/pcshop";
console.log("[INFO] - Connecting to "+connection_string+" ...");
MongoClient.connect(connection_string, function(err, db){
	if (err) throw err;

	console.log('[INFO] - Connection is established.');

	// Insert items into the products collection
	var products = db.collection('products');
	var items = [
		{'manufacturer': 'Intel', 'category':'CPUs-Processors-Desktop', 'description':'Intel Core i7-4960X Ivy Bridge-E 6-Core 3.6GHz (Turbo 4GHz) LGA 2011 130W Desktop Processor BX80633i74960X', 'price': 1049.99, 'quantity':12, 'last_updated': new Date(2014,06,26) },
		{'manufacturer': 'ASUS', 'category':'Intel Motherboards', 'description':'ASUS Sabertooth X79 LGA 2011 Intel X79 SATA 6Gb/s USB 3.0 ATX Intel Motherboard', 'price': 314.99, 'quantity':24, 'last_updated': new Date(2014,04,20) },
		{'manufacturer': 'Corsair', 'category':'Desktop Memory', 'description':'CORSAIR Dominator Platinum 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 2400 Desktop Memory Model CMD16GX3M2A2400C10', 'price': 274.99, 'quantity':120, 'last_updated': new Date(2014,06,29) },
		{'manufacturer': 'Zotac', 'category':'Desktop Graphics Card', 'description':'ZOTAC ZT-70301-10P GeForce GTX 770 2GB 256-Bit GDDR5 PCI Express 3.0 Video Card', 'price': 371.90, 'quantity':60, 'last_updated': new Date(2014,06,27) },
		{'manufacturer': 'Gigabyte', 'category':'Desktop Graphics Card', 'description':'GIGABYTE GV-N770OC-4GD GeForce GTX 770 4GB 256-Bit GDDR5 PCI Express 3.0 HDCP Ready WindForce 3X 450W Video Card', 'price': 369.99, 'quantity':30, 'last_updated': new Date(2014,06,29) }
	];

	// Enter asynchronous for each loop
	items.forEach(function(value, index, traversed_array){
		// Insert current document into mongodb
		products.insert(value, function(err, insertedDoc){
			if (err) throw err;
			assert.ok(insertedDoc.length > 0);
			console.log("[INFO] - Successfully inserted "+JSON.stringify(insertedDoc[0])+" document." );

			if (index == items.length-1){
				console.log("[INFO] - Closing connection ...");
				db.close();
			}
		});
	});
});

02_findOne.js

/**
 * A sample of findOne (retrieve a single document from a collection).
 * Pre-requisite: the database & collection created in 01_insert.js exists.
 */

var MongoClient = require('mongodb').MongoClient,
	assert=require('assert');
var connection_string = "mongodb://127.0.0.1:27017,127.0.0.1:27018,127.0.0.1:27019/pcshop";
console.log("[INFO] - Connecting to "+connection_string+" ...");
MongoClient.connect(connection_string, function(err, db){
	if (err) throw err;

	console.log('[INFO] - Connection is established.');

	var products = db.collection('products');

	// Declare the helper method for findOne Operation
	function findOne(query, callback){
		products.findOne(query, function(err, document){
			console.log('[INFO] - Dispatched findOne ...');

			if (err) throw err;

			assert.ok(document != null);

			console.log("[INFO] - findOne successfully returns "+JSON.stringify(document)+" document.");

			if (callback != null){
				callback();
			}
		});
	}

	// Find a document that has lowest Id compared to the others
	findOne({}, function(){
		// Query a document with specific criteria after prior query is finished
		var zotac_gpu_query = {'manufacturer': 'Zotac', 'category': {$regex: 'Graphics Card'}};
		findOne(zotac_gpu_query, function(){
			console.log("[INFO] - Closing connection ...");
			db.close();
		});
	});
});

03_find.js

/**
 * A sample of find query with result projection.
 * Pre-requisite: the database & collection created in 01_insert.js exists.
 */

var MongoClient = require('mongodb').MongoClient,
	assert=require('assert');
var connection_string = "mongodb://127.0.0.1:27017,127.0.0.1:27018,127.0.0.1:27019/pcshop";
console.log("[INFO] - Connecting to "+connection_string+" ...");
MongoClient.connect(connection_string, function(err, db){
	if (err) throw err;

	console.log('[INFO] - Connection is established.');

	var products = db.collection('products');

	// Declare the helper method for find Operation
	function find(query, projection, callback){
		// The result of find method is a cursor. We call toArray method here to get the actual queried documents
		products.find(query, projection).toArray(function(err, documents){
			console.log('[INFO] - Dispatched find ...');

			if (err) throw err;

			assert.ok((documents != null) && (documents.length > 0));

			console.log("[INFO] - find successfully returns "+documents.length+" documents:");
			console.dir(documents);
			if (callback != null){
				callback();
			}
		});
	}

	// Pull all documents from the products collection
	console.log("[INFO] - Pull all documents in the products collection");
	find({},{}, function(){
		// Query all documents that are categorised as 'Desktop Graphics Card'
		console.log("[INFO] - Query all documents that are categorised as 'Desktop Graphics Card'.");
		var desktop_graphics_card_query = {'category': 'Desktop Graphics Card'};
		// also, project the query results so that each of the result would exclude _id & last_updated fields
		var projection = {_id: 0, 'last_updated': 0};
		find(desktop_graphics_card_query, projection, function(){
			console.log("[INFO] - Closing connection ...");
			db.close();
		});
	});

});

04_find_gt_lt.js

/**
 * A sample of find with $gt & $lt operators.
 * Pre-requisite: the database & collection created in 01_insert.js exists.
 */

var MongoClient = require('mongodb').MongoClient,
	assert=require('assert');
var connection_string = "mongodb://127.0.0.1:27017,127.0.0.1:27018,127.0.0.1:27019/pcshop";
console.log("[INFO] - Connecting to "+connection_string+" ...");
MongoClient.connect(connection_string, function(err, db){
	if (err) throw err;

	console.log('[INFO] - Connection is established.');

	var products = db.collection('products');

	// Declare the helper method for find Operation
	function find(query, callback){
		// The result of find method is a cursor. We call toArray method here to get the actual queried documents
		var hide_id_projection = {'_id':0};
		products.find(query, hide_id_projection).toArray(function(err, documents){
			console.log('[INFO] - Dispatched find ...');

			if (err) throw err;

			assert.ok((documents != null) && (documents.length > 0));

			console.log("[INFO] - find successfully returns "+documents.length+" documents:");
			console.dir(documents);
			if (callback != null){
				callback();
			}
		});
	}

	// Pull products where their price is greater than $300.0
	console.log("[INFO] - Pull products where their price is greater than $300.0");
	var query = {'price': {$gt: 300.0}};
	find( query, function(){
		// Query all documents where their price falls between $300-$400 range.
		console.log("[INFO] - Query all documents where their price falls between $300-$400 range.");
		query.price = {$gt: 300.0, $lt: 400.0};
		find(query, function(){
			console.log("[INFO] - Closing connection ...");
			db.close();
		});
	});

});

05_find_regex.js

/**
 * A sample of find with $regex operator.
 * Pre-requisite: the database & collection created in 01_insert.js exists.
 */

var MongoClient = require('mongodb').MongoClient,
	assert=require('assert');
var connection_string = "mongodb://127.0.0.1:27017,127.0.0.1:27018,127.0.0.1:27019/pcshop";
console.log("[INFO] - Connecting to "+connection_string+" ...");
MongoClient.connect(connection_string, function(err, db){
	if (err) throw err;

	console.log('[INFO] - Connection is established.');

	var products = db.collection('products');

	// Declare the helper method for find Operation
	function find(query, callback){
		// The result of find method is a cursor. We call toArray method here to get the actual queried documents
		var hide_id_projection = {'_id':0};
		products.find(query, hide_id_projection).toArray(function(err, documents){
			console.log('[INFO] - Dispatched find ...');

			if (err) throw err;

			assert.ok((documents != null) && (documents.length > 0));

			console.log("[INFO] - find successfully returns "+documents.length+" documents:");
			console.dir(documents);
			if (callback != null){
				callback();
			}
		});
	}

	// Pull products where their description contains 'i7'
	console.log("[INFO] - Pull products where their description contains 'i7'");
	var query = {'description': {$regex: 'i7'}};
	find( query, function(){
		console.log("[INFO] - Closing connection ...");
		db.close();
	});
});

06_find_or.js

/**
 * A sample of find with $or operator.
 * Pre-requisite: the database & collection created in 01_insert.js exists.
 */

var MongoClient = require('mongodb').MongoClient,
	assert=require('assert');
var connection_string = "mongodb://127.0.0.1:27017,127.0.0.1:27018,127.0.0.1:27019/pcshop";
console.log("[INFO] - Connecting to "+connection_string+" ...");
MongoClient.connect(connection_string, function(err, db){
	if (err) throw err;

	console.log('[INFO] - Connection is established.');

	var products = db.collection('products');

	// Declare the helper method for find Operation
	function find(query, callback){
		// The result of find method is a cursor. We call toArray method here to get the actual queried documents
		var hide_id_projection = {'_id':0};
		products.find(query, hide_id_projection).toArray(function(err, documents){
			console.log('[INFO] - Dispatched find ...');

			if (err) throw err;

			assert.ok((documents != null) && (documents.length > 0));

			console.log("[INFO] - find successfully returns "+documents.length+" documents:");
			console.dir(documents);
			if (callback != null){
				callback();
			}
		});
	}

	// Pull products where their manufacturers are ASUS or Zotac
	console.log("[INFO] - Pull products where their manufacturers are ASUS or Zotac");
	var query = {$or: [{'description': 'ASUS'},{'description': 'Zotac'}]};
	find( query, function(){
		console.log("[INFO] - Closing connection ...");
		db.close();
	});
});

07_find_and.js

/**
 * A sample of find with $and operator.
 * Pre-requisite: the database & collection created in 01_insert.js exists.
 */

var MongoClient = require('mongodb').MongoClient,
	assert=require('assert');
var connection_string = "mongodb://127.0.0.1:27017,127.0.0.1:27018,127.0.0.1:27019/pcshop";
console.log("[INFO] - Connecting to "+connection_string+" ...");
MongoClient.connect(connection_string, function(err, db){
	if (err) throw err;

	console.log('[INFO] - Connection is established.');

	var products = db.collection('products');

	// Declare the helper method for find Operation
	function find(query, callback){
		// The result of find method is a cursor. We call toArray method here to get the actual queried documents
		var hide_id_projection = {'_id':0};
		products.find(query, hide_id_projection).toArray(function(err, documents){
			console.log('[INFO] - Dispatched find ...');

			if (err) throw err;

			assert.ok((documents != null) && (documents.length > 0));

			console.log("[INFO] - find successfully returns "+documents.length+" documents:");
			console.dir(documents);
			if (callback != null){
				callback();
			}
		});
	}

	// Pull products where their category is Desktop Graphics Card AND their quantity is less than to 50
	console.log("[INFO] - Pull products where their category is Desktop Graphics Card AND their quantity is less than equal to 50");
	var query = {$and: [{'category': 'Desktop Graphics Card'},{'quantity': {$lte: 50}}]};
	find( query, function(){
		console.log("[INFO] - Closing connection ...");
		db.close();
	});
});