Creating CRUD (Create, Read, Update, Delete) modules is a fundamental part of developing any web application. In this tutorial, we will explore how to create a simple CRUD operation module in a MERN (MongoDB, Express, React, Node.js) system. Before we begin, make sure you have the following installed:
– Node.js
– NPM
– MongoDB
Let’s start by creating a new project. Open your terminal and enter the following commands:
“`bash
mkdir mern-crud
cd mern-crud
npm init -y
“`
This will create a new directory called `mern-crud`, initialize a new NPM project, and create a `package.json` file.
Next, we need to install the required dependencies. Enter the following commands in your terminal:
“`bash
npm install express mongoose body-parser cors
npm install nodemon –save-dev
“`
Here, we are installing the following packages:
– `express`: to create a server
– `mongoose`: to connect to MongoDB
– `body-parser`: to parse incoming request bodies
– `cors`: to enable cross-origin resource sharing
– `nodemon`: to automatically restart the server on changes
Now, let’s create the server. Create a new file called `server.js` in the root directory and add the following code:
“`javascript
const express = require(‘express’);
const mongoose = require(‘mongoose’);
const bodyParser = require(‘body-parser’);
const cors = require(‘cors’);
const app = express();
const PORT = process.env.PORT || 5000;
app.use(bodyParser.json());
app.use(cors());
mongoose.connect(‘mongodb://localhost/mern-crud’, {
useNewUrlParser: true,
useUnifiedTopology: true
});
const connection = mongoose.connection;
connection.once(‘open’, () => {
console.log(‘MongoDB database connection established successfully’);
});
app.listen(PORT, () => {
console.log(`Server is running on port ${PORT}`);
});
“`
Here, we are importing the required packages, creating an instance of the Express application, setting the port number, and connecting to the MongoDB database. We are also setting up the middleware for parsing incoming request bodies and enabling CORS.
To start the server, enter the following command in your terminal:
“`bash
npm run dev
“`
This will start the server using `nodemon`.
Now, let’s create the CRUD operation modules for our application. First, we need to create a `model` for our data. Create a new file called `user.model.js` in a `models` directory and add the following code:
“`javascript
const mongoose = require(‘mongoose’);
const Schema = mongoose.Schema;
const userSchema = new Schema({
username: { type: String, required: true },
email: { type: String, required: true },
password: { type: String, required: true },
}, {
timestamps: true
});
const User = mongoose.model(‘User’, userSchema);
module.exports = User;
“`
Here, we are defining the schema for our `User` model. We are requiring a `username`, `email`, and `password` field, and adding a timestamp for when the data was created. We are then creating a new instance of the `User` model and exporting it.
Next, we need to create the routes for our CRUD operations. Create a new file called `users.js` in a `routes` directory and add the following code:
“`javascript
const router = require(‘express’).Router();
let User = require(‘../models/user.model’);
router.route(‘/’).get((req, res) => {
User.find()
.then(users => res.json(users))
.catch(err => res.status(400).json(`Error: ${err}`));
});
router.route(‘/:id’).get((req, res) => {
User.findById(req.params.id)
.then(user => res.json(user))
.catch(err => res.status(400).json(`Error: ${err}`));
});
router.route(‘/add’).post((req, res) => {
const username = req.body.username;
const email = req.body.email;
const password = req.body.password;
const newUser = new User({
username,
email,
password,
});
newUser.save()
.then(() => res.json(‘User added!’))
.catch(err => res.status(400).json(`Error: ${err}`));
});
router.route(‘/:id’).delete((req, res) => {
User.findByIdAndDelete(req.params.id)
.then(() => res.json(‘User deleted.’))
.catch(err => res.status(400).json(`