This guide will walk you through the process of connecting to a MongoDB database using Node.js within your Sealos DevBox project.

Prerequisites

A Sealos DevBox project with Node.js environment
A MongoDB database created using the Database app in Sealos

Install Required Packages

In your Cursor terminal, install the necessary packages:

npm install mongodb dotenv

This command installs:

mongodb: The official MongoDB driver for Node.js
dotenv: A zero-dependency module that loads environment variables from a .env file

Connection Setup

Set up the environment variables

First, let's set up the environment variables for our database connection. Create a .env file in your project root with the following content:

.env

MONGO_URI=mongodb://your_username:your_password@your_database_host:27017/your_database_name?authSource=admin

Replace the placeholders with your actual MongoDB credentials from the Database app in Sealos.

Create a connection file

Next, create a file named db.js with the following content:

db.js

const { MongoClient } = require('mongodb');
require('dotenv').config();
 
const uri = process.env.MONGO_URI;
const client = new MongoClient(uri);
 
async function connectToDatabase() {
  try {
    await client.connect();
    console.log('Connected to MongoDB');
    return client.db();
  } catch (error) {
    console.error('Error connecting to MongoDB:', error);
    process.exit(1);
  }
}
 
module.exports = { connectToDatabase, client };

This file creates a MongoDB client and exports a function to connect to the database.

Create database operations

Now, let's create a file named dbOperations.js to handle our database operations:

dbOperations.js

const { connectToDatabase, client } = require('./db');
 
async function createDocument(collection, document) {
  const db = await connectToDatabase();
  const result = await db.collection(collection).insertOne(document);
  console.log(`Document inserted with _id: ${result.insertedId}`);
  return result.insertedId;
}
 
async function readDocuments(collection, query = {}) {
  const db = await connectToDatabase();
  const documents = await db.collection(collection).find(query).toArray();
  console.log('Documents found:', documents);
  return documents;
}
 
async function updateDocument(collection, filter, update) {
  const db = await connectToDatabase();
  const result = await db.collection(collection).updateOne(filter, { $set: update });
  console.log(`${result.modifiedCount} document(s) updated`);
  return result.modifiedCount;
}
 
async function deleteDocument(collection, filter) {
  const db = await connectToDatabase();
  const result = await db.collection(collection).deleteOne(filter);
  console.log(`${result.deletedCount} document(s) deleted`);
  return result.deletedCount;
}
 
module.exports = {
  createDocument,
  readDocuments,
  updateDocument,
  deleteDocument
};

Create a main script

Finally, let's create a main.js file to demonstrate all the operations:

main.js

const {
  createDocument,
  readDocuments,
  updateDocument,
  deleteDocument
} = require('./dbOperations');
const { client } = require('./db');
 
async function main() {
  try {
    // Create a document
    const newEmployeeId = await createDocument('employees', { name: 'John Doe', position: 'Developer' });
    
    // Read all documents
    await readDocuments('employees');
    
    // Update a document
    await updateDocument('employees', { _id: newEmployeeId }, { position: 'Senior Developer' });
    
    // Read the updated document
    await readDocuments('employees', { _id: newEmployeeId });
    
    // Delete the document
    await deleteDocument('employees', { _id: newEmployeeId });
    
    // Confirm deletion
    await readDocuments('employees');
    
  } catch (error) {
    console.error('An error occurred:', error);
  } finally {
    await client.close();
  }
}
 
main();

Usage

To run the script, use the following command in your Cursor terminal:

node main.js

This will execute all the operations defined in the main function, demonstrating the connection to the database, document creation, reading, updating, and deletion.

Best Practices

Use environment variables for database credentials.
Use connection pooling for better performance (MongoDB driver handles this automatically).
Always handle potential errors using try-catch blocks.
Close the database connection after operations are complete.
Use indexes for frequently queried fields to improve performance.

Troubleshooting

If you encounter connection issues:

Verify your MongoDB credentials in the .env file.
Ensure your MongoDB database is running and accessible.
Check for any network restrictions in your DevBox environment.
Confirm that the mongodb package is correctly installed.

For more detailed information on using MongoDB with Node.js, refer to the official MongoDB Node.js driver documentation.

Node.js