As more and more web applications move towards a microservices architecture, building and maintaining a well-designed and well-documented RESTful API is becoming increasingly important.
RESTful APIs play an essential role in enabling communication between different applications, services, and devices, and they are rapidly becoming the industry standard for web service design. However, designing a RESTful API is not an easy task, and it requires careful consideration of various design principles and best practices.

In this article, I will show you top 5 design practices of a RESTful API using ExpressJS, a popular Node.js framework. Whether you're a beginner looking to learn about RESTful API design or an experienced developer seeking to brush up on your skills, this guide is for you. We'll explore how to follow REST principles, use middleware for validation and authentication, use a consistent naming convention for URIs, use descriptive HTTP response codes, and document your API to make it more accessible to other developers.

Follow the REST principles REST (Representational State Transfer) is a set of architectural principles that are used to design web services. A RESTful API should follow the principles of REST, such as using HTTP methods (GET, POST, PUT, DELETE) for different actions, using URIs to identify resources, and using HTTP response codes to indicate success or failure. Following the REST principles will help ensure that your API is consistent and easy to understand.

To follow the REST principles, you should use HTTP methods to perform different actions on resources. For example, use the GET method to retrieve a resource, the POST method to create a new resource, the PUT method to update an existing resource, and the DELETE method to delete a resource. Here's an example of how to implement a GET request in ExpressJS:

app.get('/users', (req, res) => {
  // Code to retrieve all users from the database
  res.status(200).send(users);
});

Use middleware for validation and authentication Middleware functions are functions that are called before a request is processed by the server. Middleware can be used to validate user input, authenticate users, and perform other tasks that need to be done before the request is handled by the server. Using middleware for validation and authentication can help make your API more secure and reliable.

For example, Express has a middleware that can be used for validation called express-validator. This middleware is specifically designed for validating input data in ExpressJS applications. Here's an example of how to use express-validator in ExpressJS:

import express from 'express';
import { check, validationResult } from 'express-validator';
const app = express();

app.post('/users', [
  check('username').isLength({ min: 5 }),
  check('email').isEmail(),
  check('password').isStrongPassword(),
], (req, res) => {
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(400).json({ errors: errors.array() });
  }

  // Code to create a new user in the database
  res.status(201).send('User created successfully');
});

Use a consistent naming convention for URIs URIs should be easy to read and understand. Use a consistent naming convention for URIs so that users can easily understand how to access the resources they need. For example, use plural nouns to identify collections of resources (e.g. /users), and use singular nouns to identify individual resources (e.g. /users/{userId}). Here's an example of how to use a consistent naming convention in ExpressJS:

app.get('/users/:userId', (req, res) => {
  const userId = req.params.userId;
  // Code to retrieve a user by ID from the database
  res.status(200).send(user);
});

In this example, we use the check method from express-validator to validate the username, email, and password fields of the request body. We also use the validationResult method to check for validation errors and return them in a JSON format if there are any. If there are no errors, we can proceed with creating the new user in the database.

Use descriptive HTTP response codes HTTP response codes should be descriptive and informative. Use the appropriate HTTP response code to indicate the status of a request. For example, use a 200 status code to indicate success, a 400 status code to indicate a bad request, and a 401 status code to indicate unauthorized access. Here's an example of how to use descriptive HTTP response codes in ExpressJS:

app.post('/login', (req, res) => {
  const {username, password} = req.body;
 if (authenticate(username, password)) {
    res.status(200).send('Login successful');
  } else {
    res.status(401).send('Unauthorized');
  }
});

Document your API Documenting your API is essential for its usability and maintainability. Use a tool like Swagger or OpenAPI to generate documentation for your API. Your documentation should include information about the available endpoints, the parameters required for each endpoint, and the response codes that may be returned. Documenting your API will make it easier for other developers to use and understand your API. Here's an example of how to document an endpoint in ExpressJS:

/**
 * @swagger
 * /users/{userId}:
 *   get:
 *     summary: Get a user by ID
 *     parameters:
 *       - in: path
 *         name: userId
 *         required: true
 *         schema:
 *           type: string
 *     responses:
 *       200:
 *         description: OK
 *         content:
 *           application/json:
 *             schema:
 *               $ref: '#/components/schemas/User'
 *       404:
 *         description: User not found
 */
app.get('/users/:userId', (req, res) => {
  const userId = req.params.userId;
  // Code to retrieve a user by ID from the database

In conclusion, building a well-designed RESTful API using ExpressJS is essential for creating scalable, reliable, and maintainable applications. By following the top 5 design practices we have discussed - using REST principles, using middleware for validation and authentication, using a consistent naming convention for URIs, using descriptive HTTP response codes, and documenting your API - you can create a robust and user-friendly API that meets the needs of your users.

Remember, the key to building a successful API is to put the needs of your users first. By focusing on creating a simple and intuitive user experience, you can ensure that your API is easy to use and easy to maintain.

Follow these design practices and build your RESTful API with confidence!

Happy Hacking!

Bentil here🚀
Which of these practices have you been using? Do you have any other which will be helpful for beginners? Kindly share them in the comments section.

Top 5 Design Practices of a RESTFUL API using Express.JS