In this guide, I’m going to make a simple Node.js CRUD API application with Express and MongoDB. I’ll create a products table and will implement the following APIs methods:

Method	URL	Action
POST	products/create	create new product
GET	products	retrieve all products
GET	products/id	retrieve product where id=id
PUT	products/update/id	update product where id=id
DELETE	products/delete/id	delete product where id=id

Table of Contents

1. Create Project and Install Dependencies
2. Connect to MongoDB
3. Create Product Model
4. Create Product Controller
5. Register Product Routes
6. The Overview
7. Run and See Output

Step 1 : Create Project and Install Dependencies

Install the Express application generator globally using this command if you didn’t install:

# with NPX command (available in Node.js 8.2.0)
npx express-generator

# with NPM command
npm install -g express-generator

Now go to the project folder and create an express project called ‘crud-api-mongodb‘:

# create project
express --view=ejs nodejs-api-crud-mongodb

# go to the project folder:
cd nodejs-api-crud-mongodb

We need to install the mongoose package for MongoDB:

npm install --save mongoose

Step 2 : Connect to MongoDB

In the root of the project folder, create a folder called ‘lib‘. Under lib folder make a file named ‘db.js‘. Open the newly created db.js file and paste the below code:

// Set up mongoose connection
const mongoose = require('mongoose');
let database_url = 'mongodb://localhost:27017/testdb';

// Connecting to the database
mongoose.connect(database_url, {
    keepAlive: true,
    useNewUrlParser: true,
    useUnifiedTopology: true,
    useFindAndModify: false,
}).then(() => {
    console.log("Successfully connected to the database");
}).catch(err => {
    console.log('Could not connect to the database. Exiting now...', err);
    process.exit();
});

module.exports = mongoose.connection;

In the database_url variable, enter your database URL. You can set remote URL too. I’ve set the localhost URL. In the last of the database_url, the testdb is the database name.

Now open app.js file and add this line to include the database.

// database connection
var dbConn  = require('./lib/db');

If you run the project (npm start) and everything is fine, you’ll see the connection successful message.

Step 3 : Create Product Model

In the root folder, make a directory named ‘models‘. Under models, create a file called ‘product.js‘. This is the product model. Let’s define the products table schema.

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

let ProductSchema = new Schema({
    name: {type: String, required: true, max: 100},
    price: {type: Number, required: true},
});

// Export the model
module.exports = mongoose.model('Product', ProductSchema);

Step 4 : Create Product Controller

Again in the root directory of the project create a folder named ‘controllers‘. Under controllers folder, make a file called ‘product.js‘. We will write make create, read, update and delete product methods in this controller.

Open the newly created product controller and paste this code:

// include product model
const Product = require('../models/product');

// create a new Product.
exports.product_create = function (req, res) {
    // validate request
    if(!req.body.name || !req.body.price) {
        return res.status(400).send({
            success: false,
            message: "Please enter product name and price"
        });
    }

    // create a product
    let product = new Product(
        {
            name: req.body.name,
            price: req.body.price
        }
    );

    // save product in the database.
    product.save()
        .then(data => {
            res.send({
                success: true,
                message: 'Product successfully created',
                data: data
            });
        }).catch(err => {
        res.status(500).send({
            success: false,
            message: err.message || "Some error occurred while creating the product."
        });
    });
};

// retrieve and return all products.
exports.all_products = (req, res) => {
    Product.find()
        .then(data => {
            var message = "";
            if (data === undefined || data.length == 0) message = "No product found!";
            else message = 'Products successfully retrieved';

            res.send({
                success: true,
                message: message,
                data: data
            });
        }).catch(err => {
        res.status(500).send({
            success: false,
            message: err.message || "Some error occurred while retrieving products."
        });
    });
};

// find a single product with a id.
exports.product_details = (req, res) => {
    Product.findById(req.params.id)
        .then(data => {
            if(!data) {
                return res.status(404).send({
                    success: false,
                    message: "Product not found with id " + req.params.id
                });
            }
            res.send({
                success: true,
                message: 'Product successfully retrieved',
                data: data
            });
        }).catch(err => {
        if(err.kind === 'ObjectId') {
            return res.status(404).send({
                success: false,
                message: "Product not found with id " + req.params.id
            });
        }
        return res.status(500).send({
            success: false,
            message: "Error retrieving product with id " + req.params.id
        });
    });
};

// update a product  by the id.
exports.product_update = (req, res) => {
    // validate request
    if(!req.body.name || !req.body.price) {
        return res.status(400).send({
            success: false,
            message: "Please enter product name and price"
        });
    }

    // find product and update
    Product.findByIdAndUpdate(req.params.id, {
        $set: req.body
    }, {new: true})
        .then(data => {
            if(!data) {
                return res.status(404).send({
                    success: false,
                    message: "Product not found with id " + req.params.id
                });
            }
            res.send({
                success: true,
                data: data
            });
        }).catch(err => {
        if(err.kind === 'ObjectId') {
            return res.status(404).send({
                success: false,
                message: "Product not found with id " + req.params.id
            });
        }
        return res.status(500).send({
            success: false,
            message: "Error updating product with id " + req.params.id
        });
    });
};

// delete a product with the specified id.
exports.product_delete = (req, res) => {
    Product.findByIdAndRemove(req.params.id)
        .then(data => {
            if (!data) {
                return res.status(404).send({
                    success: false,
                    message: "Product not found with id " + req.params.id
                });
            }
            res.send({
                success: true,
                message: "Product successfully deleted!"
            });
        }).catch(err => {
        if (err.kind === 'ObjectId' || err.name === 'NotFound') {
            return res.status(404).send({
                success: false,
                message: "Product not found with id " + req.params.id
            });
        }
        return res.status(500).send({
            success: false,
            message: "Could not delete product with id " + req.params.id
        });
    });
};

In this controller, I’ve created the CRUD functions.

Step 5 : Register Product Routes

In this step, we will register routes to connect to the product controller’s methods.

Go to the routes folder and make a file named ‘products.js‘. Then paste this code:

const express = require('express');
const router = express.Router();

// include product controller
const product_controller = require('../controllers/product');

// routes
router.get('/', product_controller.all_products);
router.post('/create', product_controller.product_create);
router.get('/:id', product_controller.product_details);
router.put('/update/:id', product_controller.product_update);
router.delete('/delete/:id', product_controller.product_delete);

module.exports = router;

We’ve defined all product CRUD routes. Let’s import the product routes to app.js. After that, the routes will work.

var productsRouter = require('./routes/products');

app.use('/products', productsRouter);

Done. Our project is ready to run…! ?

Step 6 : The Overview

The final app.js looks like:

var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');

// database connection
var dbConn  = require('./lib/db');

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var productsRouter = require('./routes/products');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/users', usersRouter);
app.use('/products', productsRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;

The package.json file looks like:

{
  "name": "nodejs-api-crud-mongodb",
  "version": "0.0.0",
  "private": true,
  "scripts": {
    "start": "node ./bin/www"
  },
  "dependencies": {
    "cookie-parser": "~1.4.4",
    "debug": "~2.6.9",
    "ejs": "~2.6.1",
    "express": "~4.16.1",
    "http-errors": "~1.6.3",
    "mongoose": "^5.7.4",
    "morgan": "~1.9.1"
  }
}

Step 7 : Run and See Output

We’ve finished all the tasks. Let run the project using this command:

npm start

Our project will be run on port 3000 and the localhost URL looks like: http://localhost:3000. If you visit this link, you’ll see a message like ‘ Welcome to Express’.

Now let’s test the APIs using Postman application.

Create a Product API: http://localhost:3000/products/create

Retrieve all Products API: http://localhost:3000/products

Retrieve Single Product API: http://localhost:3000/products/:id

Update Product API: http://localhost:3000/products/update/:id

Delete Product API: http://localhost:3000/products/delete/:id

The tutorial is over. You can download this project from GitHub. Thank you. ?