Step 0: Understanding MongoDB

MongoDB is a document-oriented database. Unlike relational databases:

• There are no tables; instead, we use collections.

• Records are called documents and are stored in JSON-like format.

• MongoDB is schema-less, meaning documents in the same collection can have different fields.

Think of MongoDB as a digital notebook where each page is a structured JSON entry. 📒

Step 1: Install MongoDB and Node.js

1. Install MongoDB Community Server from the official website.

2. Install Node.js if you haven’t already.

3. Use MongoDB Compass (GUI) to visualize your database (optional but helpful).

Step 2: Set Up Node.js Project

Create a project folder:

mkdir mongodb-nodejs-demo
cd mongodb-nodejs-demo
npm init -y

Install the required Node.js packages:

npm install express mongodb body-parser

• Express → server framework

• mongodb → official MongoDB Node.js driver

• body-parser → parse JSON request bodies

Step 3: Connect to MongoDB

Create a file server.js:

const express = require('express');
const bodyParser = require('body-parser');
const { MongoClient } = require('mongodb');

const app = express();
app.use(bodyParser.json());

const PORT = 3000;
const url = 'mongodb://localhost:27017';
const dbName = 'company_db';

MongoClient.connect(url, { useUnifiedTopology: true }, (err, client) => {
    if (err) throw err;

    console.log('Connected to MongoDB successfully!');
    const db = client.db(dbName);
    const employees = db.collection('employees');

    // Test endpoint
    app.get('/', (req, res) => {
        res.send('MongoDB Node.js API is running.');
    });

    app.listen(PORT, () => {
        console.log(`Server running at http://localhost:${PORT}`);
    });
});

Explanation:

• MongoClient.connect() → connects to the MongoDB server

• db.collection('employees') → selects (or creates) a collection

• useUnifiedTopology: true → modern connection management

Step 4: Insert Documents

Inside the MongoClient.connect() callback, add:

// Insert one employee
employees.insertOne({
    name: 'Alice Smith',
    email: 'alice@example.com',
    position: 'Developer',
    salary: 5000
}, (err, result) => {
    if (err) throw err;
    console.log('Employee inserted:', result.insertedId);
});

Explanation:

• Documents are JSON-like objects ({ key: value })

• _id is automatically generated if not provided

Step 5: Read Documents

// Fetch all employees
employees.find({}).toArray((err, docs) => {
    if (err) throw err;
    console.log('Employees:', docs);
});

Explanation:

• find({}) → retrieves all documents

• toArray() → converts cursor to array for easier manipulation

Step 6: Update Documents

// Update employee salary
employees.updateOne(
    { name: 'Alice Smith' },
    { $set: { salary: 5500 } },
    (err, result) => {
        if (err) throw err;
        console.log('Documents updated:', result.modifiedCount);
    }
);

Explanation:

• $set → updates specific fields without affecting others

• updateOne() → updates only the first matching document

Step 7: Delete Documents

// Delete an employee
employees.deleteOne({ name: 'Alice Smith' }, (err, result) => {
    if (err) throw err;
    console.log('Documents deleted:', result.deletedCount);
});

Explanation:

• deleteOne() removes a single matching document

• MongoDB also supports deleteMany() for bulk deletions

Step 8: Wrap Up

In this tutorial, you learned:

1. The difference between relational and NoSQL databases

2. How to connect Node.js to MongoDB

3. How to insert, read, update, and delete documents

4. Why collections and documents are flexible and schema-less

MongoDB is ideal for projects where flexibility is important, and it integrates well with modern web applications.