NodeJs MongoDB

Node.js MongoDB: A Guide to Using MongoDB with Node.js

MongoDB is a popular NoSQL database that stores data in a flexible, JSON-like format, making it ideal for applications that require a scalable and schema-less design. When combined with Node.js, developers can create powerful applications that leverage the strengths of both technologies.

Prerequisites

Ensure you have the following:

Node.js: Installed from nodejs.org.
MongoDB: Installed and running, or use a cloud service like MongoDB Atlas.
MongoDB Driver for Node.js: Installed in your Node.js project.

Step 1: Set Up the Project

Create a project directory (if not already done):
bash
mkdir node-mongodb cd node-mongodb
Initialize a Node.js project:
bash
npm init -y
Install the MongoDB driver:
bash
npm install mongodb

Step 2: Connect to MongoDB

Create a file named app.js:
bash
touch app.js

Open app.js and add the following code to connect to the MongoDB server:

javascript

const { MongoClient } = require('mongodb');

// Replace the following with your MongoDB connection string
const uri = 'mongodb://localhost:27017';
const client = new MongoClient(uri);

async function run() {
    try {
        // Connect to the MongoDB cluster
        await client.connect();
        console.log('Connected to MongoDB');

        // Perform operations here...

    } catch (error) {
        console.error('Error connecting to MongoDB:', error);
    } finally {
        // Close the connection
        await client.close();
    }
}

run().catch(console.error);

Step 3: Create a Database and Collection

To work with MongoDB, you need to create a database and a collection. Collections are similar to tables in relational databases.

Create a database and collection:

You can modify the run function to create a database and a collection:

javascript

const dbName = 'mydatabase';
const collectionName = 'users';

async function run() {
    try {
        await client.connect();
        console.log('Connected to MongoDB');

        const database = client.db(dbName);
        const collection = database.collection(collectionName);

        console.log(`Database: ${dbName}, Collection: ${collectionName}`);

        // Perform operations here...

    } catch (error) {
        console.error('Error connecting to MongoDB:', error);
    } finally {
        await client.close();
    }
}

Step 4: Insert Documents into the Collection

You can insert documents (similar to rows in SQL) into the MongoDB collection:

javascript

async function run() {
    try {
        await client.connect();
        console.log('Connected to MongoDB');

        const database = client.db(dbName);
        const collection = database.collection(collectionName);

        // Insert a single document
        const user = { name: 'Alice', email: '[email protected]' };
        const result = await collection.insertOne(user);
        console.log(`Inserted document with _id: ${result.insertedId}`);

        // Insert multiple documents
        const users = [
            { name: 'Bob', email: '[email protected]' },
            { name: 'Charlie', email: '[email protected]' }
        ];
        const insertManyResult = await collection.insertMany(users);
        console.log(`${insertManyResult.insertedCount} documents were inserted`);
        
    } catch (error) {
        console.error('Error connecting to MongoDB:', error);
    } finally {
        await client.close();
    }
}

Step 5: Retrieve Documents from the Collection

You can retrieve documents using the find method:

javascript

async function run() {
    try {
        await client.connect();
        console.log('Connected to MongoDB');

        const database = client.db(dbName);
        const collection = database.collection(collectionName);

        // Find all documents
        const allUsers = await collection.find().toArray();
        console.log('All Users:', allUsers);

        // Find a specific user
        const user = await collection.findOne({ name: 'Alice' });
        console.log('Found User:', user);

    } catch (error) {
        console.error('Error connecting to MongoDB:', error);
    } finally {
        await client.close();
    }
}

Step 6: Update Documents

You can update existing documents in the collection using the updateOne or updateMany methods:

javascript

async function run() {
    try {
        await client.connect();
        console.log('Connected to MongoDB');

        const database = client.db(dbName);
        const collection = database.collection(collectionName);

        // Update a specific user
        const result = await collection.updateOne(
            { name: 'Alice' }, // Filter
            { $set: { email: '[email protected]' } } // Update
        );

        console.log(`${result.modifiedCount} document(s) were updated`);
        
    } catch (error) {
        console.error('Error connecting to MongoDB:', error);
    } finally {
        await client.close();
    }
}

Step 7: Delete Documents

You can delete documents using the deleteOne or deleteMany methods:

javascript

async function run() {
    try {
        await client.connect();
        console.log('Connected to MongoDB');

        const database = client.db(dbName);
        const collection = database.collection(collectionName);

        // Delete a specific user
        const result = await collection.deleteOne({ name: 'Bob' });
        console.log(`${result.deletedCount} document(s) were deleted`);

    } catch (error) {
        console.error('Error connecting to MongoDB:', error);
    } finally {
        await client.close();
    }
}

Step 8: Run the Application

To run the Node.js script and perform CRUD operations, execute the following command in your terminal:

bash

node app.js

You will see the results of the CRUD operations in the console.

Conclusion

In this guide, you’ve learned how to:

Set up a Node.js project to connect to MongoDB.
Perform basic CRUD operations: Create, Read, Update, and Delete documents in a MongoDB collection.
Understand how to structure your Node.js application to interact with MongoDB effectively.

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