Connecting MongoDB to Express App

detailed line by line comments can be found on the source code

This guide explains how to connect MongoDB to an Express app using Mongoose, a MongoDB object modeling tool designed to work in an asynchronous environment.

Prerequisites

Before proceeding, make sure you have the following installed:

• Node.js
• MongoDB

Dependencies

npm i express mongoose mongodb nodemon

Step 1: Set Up MongoDB Connection

Create a file named db.js in your project directory with the following content:

// db.js
const mongoose = require('mongoose');

const uri = 'mongodb-connection-string';

module.exports = () => {
  return mongoose.connect(uri, { useNewUrlParser: true, useUnifiedTopology: true });
};

Replace mongodb-connection-string with the actual MongoDB connection string.

Step 2: Set Up Express App

Create a file named index.js in your project directory with the following content:

// index.js
const express = require('express');
const bodyParser = require('body-parser');

const app = express();
const connectDb = require('./db');
const jpadsController = require('./controllers/jpads-controller');

app.use(bodyParser.json());
app.use('/api/jpads', jpadsController);

connectDb().then(() => {
  console.log('MongoDb connected');
  app.listen(3000, () => console.log('Server started on http://localhost:3000'));
}).catch(err => {
  console.log('MongoDb connection error: ', err);
});

This code sets up an Express app, includes body-parser middleware, connects to MongoDB using the connectDb function from db.js and then starts the server on port 3000.

Step 3: Create Controllers

Create a file named jpads-controller.js inside a controllers folder.

// controllers/jpads-controller.js
const express = require('express');
const router = express.Router();
const ObjectId = require('mongoose').Types.ObjectId;
const Jpads = require('../models/jpads');

// CRUD operations go here

module.exports = router;

Step 4: Start the Application

npm start