MongoDB & Node.js

Node.js is a rapidly growing technology that has been overtaking the world of server-side programming with surprising speed. 

One of the most popular NoSQL database is MongoDB and is a perfect fit for Node.JS applications.

Node.js can be used in database applications.

Lets get started

1. You have to install the package
• Install via npm
• npm install mongodb
2. Next lets connect MongoDB with Node.js
• After installing package, go to your Node.js, create a variable and call the MongoDB to work
• var MongoClient = require('mongodb').MongoClient;
• example code:
• var MongoClient = require('mongodb').MongoClient;
  
  // Connect to the db
  MongoClient.connect("mongodb://localhost:27017/exampleDb", function(err, db) {
    if(!err) {
      console.log("We are connected");
    }
  });
• The Db.connect method here, use a uri  (Uniform Resource Identifier) to connect to the Mongo database, where localhost:27017 is the server host and port and exampleDb the db we wish to connect to.
• After the url notice the hash containing the auto_reconnect key ,  Auto reconnect tells the driver to retry sending a command to the server if there is a failure during its execution.
3. Creating DB using Node.js
• Use the MongoDM db creating command into Node.js file
• Create a database called "uki":
• Sample Code:
• var MongoClient = require('mongodb').MongoClient;
  var url = "mongodb://localhost:27017/uki";
  
  MongoClient.connect(url, function(err, db) {
    if (err) throw err;
    console.log("Database created!");
    db.close();
  });
• Save this file [eg: Uki.js] and go to Terminal, start MongoDB, and run to open this file like this node uki.js you'll got a out put Database created!
4. Creating Table
• To create a table in MongoDB, we use the method:createCollection()
• var MongoClient = require('mongodb').MongoClient;
  var url = "mongodb://localhost:27017/uki";
  
  MongoClient.connect(url, function(err, db) {
    if (err) throw err;
    db.createCollection("Students", function(err, res) {
      if (err) throw err;
      console.log("Table created!");
      db.close();
    });
  });
• Save this file [eg: Uki.js] and go to Terminal, start MongoDB, and run to open this file like this node uki.js you'll got a out put Table created!
5. Insert Records into Table
• Sample Code:
• var MongoClient = require('mongodb').MongoClient;
  var url = "mongodb://localhost:27017/uki";
  MongoClient.connect(url, function(err, db) {
    if (err) throw err;
    var myobj = { name: "Abiramy", address: "Sullipuram" };  db.collection("Students").insertOne(myobj, function(err, res) {     if (err) throw err;
      console.log("1 record inserted");
      db.close();
    });
  });
• Save this file [eg: Uki.js] and go to Terminal, start MongoDB, and run to open this file like this node uki.js you'll got a out put 1 record inserted
• To add many Records in a time:
• MongoClient.connect(url, function(err, db) {
    if (err) throw err;
     var myobj = [
      { name: 'Mino', address: 'Jaffna'},
      { name: 'Sheno', address: 'Jaffna'},
      { name: 'Shama', address: 'Jaffna'},
      { name: 'Janu', address: 'Jaffna'},
      { name: 'Dialni', address: 'Karainagar'},                                                                  ];                                                                                                                                 db.collection("Students").insert(myobj, function(err, res) {
       if (err) throw err;
      console.log("Number of records inserted: " + res.insertedCount);
      db.close();
    });
  });
6. Find Command
• To select data from a table in MongoDB, we can use the .find() method.
• To find all
• var MongoClient = require('mongodb').MongoClient;                                                var url = "mongodb://localhost:27017/uki";
  MongoClient.connect(url, function(err, db) {
    if (err) throw err;
     db.collection("Students").find({}).toArray(function(err, result) {
       if (err) throw err;
  console.log(result);
      db.close();
    });
  });
• Using Variables
• MongoClient.connect(url, function(err, db) {
    if (err) throw err;
    var stu1 = { address: "Jaffna" };  db.collection("Students").find(stu1).toArray(function(err, result) {
      if (err) throw err;
      console.log(result);
      db.close();
      });
      });
7. Sorting
•  Use to sort Data s
• { name: 1 } // ascending
• { name: -1 } // descending
• var http = require('http');
  var MongoClient = require('mongodb').MongoClient;
  var url = "mongodb://localhost:27017/uki";
  
  MongoClient.connect(url, function(err, db) {
    if (err) throw err;
    var mysort = { name: 1 };
    db.collection("students").find().sort(mysort).toArray(function(err, result) {
      if (err) throw err;
      console.log(result);
      db.close();
    });
  });