**Course Title:** Mastering Express.js: Building Scalable Web Applications and APIs **Section Title:** Building RESTful APIs **Topic:** Creating RESTful routes and controllers in Express.js **Overview** In this topic, we will explore the process of creating RESTful routes and controllers in Express.js. We will delve into the world of RESTful API design and learn how to structure our routes and controllers to handle CRUD operations. **RESTful Route Structure** In a RESTful API, each route corresponds to a resource. For example, in a blog API, we might have routes for creating, reading, updating, and deleting blog posts. Here is an example of how we might structure our routes: ```diff const express = require('express'); const router = express.Router(); // Create a new blog post router.post('/blog-posts', createBlogPost); // Get all blog posts router.get('/blog-posts', getBlogPosts); // Get a single blog post by ID router.get('/blog-posts/:id', getBlogPost); // Update a single blog post by ID router.put('/blog-posts/:id', updateBlogPost); // Delete a single blog post by ID router.delete('/blog-posts/:id', deleteBlogPost); ``` In this example, we have created five routes that correspond to the five basic CRUD operations: create, read, update, and delete. **Controllers** In Express.js, controllers are functions that handle incoming requests and return responses. They are typically used to encapsulate the logic of our routes, making it easier to manage and maintain our code. Here is an example of how we might structure our controllers: ```diff // blog-post.controller.js const BlogPost = require('../models/BlogPost'); exports.createBlogPost = async (req, res) => { const blogPost = new BlogPost(req.body); await blogPost.save(); res.status(201).json(blogPost); }; exports.getBlogPosts = async (req, res) => { const blogPosts = await BlogPost.find().exec(); res.json(blogPosts); }; exports.getBlogPost = async (req, res) => { const blogPost = await BlogPost.findById(req.params.id).exec(); if (!blogPost) { res.status(404).json({ message: 'Blog post not found' }); } else { res.json(blogPost); } }; exports.updateBlogPost = async (req, res) => { const blogPost = await BlogPost.findByIdAndUpdate(req.params.id, req.body, { new: true }); res.json(blogPost); }; exports.deleteBlogPost = async (req, res) => { await BlogPost.findByIdAndRemove(req.params.id); res.status(204).json({ message: 'Blog post deleted' }); }; ``` In this example, we have created a controller file that exports five functions, each corresponding to one of the routes we defined earlier. **Best Practices** Here are some best practices to keep in mind when creating RESTful routes and controllers: 1. **Use clear and concise route names**: Use route names that clearly describe the resource being manipulated. 2. **Use HTTP verbs correctly**: Use HTTP verbs (e.g., GET, POST, PUT, DELETE) to indicate the type of operation being performed. 3. **Use route parameters**: Use route parameters to pass data to your controllers. 4. **Use async/await**: Use async/await to handle asynchronous operations. 5. **Use a consistent naming convention**: Use a consistent naming convention for your routes and controllers. **Example Use Cases** Here are some example use cases for the routes we defined earlier: 1. Creating a new blog post: ```bash POST /blog-posts HTTP/1.1 Content-Type: application/json { "title": "My new blog post", "content": "This is the content of my new blog post" } ``` 2. Getting all blog posts: ```bash GET /blog-posts HTTP/1.1 ``` 3. Getting a single blog post by ID: ```bash GET /blog-posts/12345 HTTP/1.1 ``` 4. Updating a single blog post by ID: ```bash PUT /blog-posts/12345 HTTP/1.1 Content-Type: application/json { "title": "My updated blog post", "content": "This is the updated content of my blog post" } ``` 5. Deleting a single blog post by ID: ```bash DELETE /blog-posts/12345 HTTP/1.1 ``` **Conclusion** In this topic, we covered the process of creating RESTful routes and controllers in Express.js. We learned how to structure our routes and controllers to handle CRUD operations and how to use best practices to ensure our code is readable and maintainable. **External Resources** * [Express.js Documentation](https://expressjs.com/en/guide/routing.html) * [RESTful API Design](https://www.smashingmagazine.com/2018/06/restful-api-design-principles) **What's Next?** In the next topic, we will cover handling API requests and responses in JSON format. **Leave a Comment or Ask for Help** If you have any questions or need help with implementing the concepts covered in this topic, please leave a comment below. We will respond as soon as possible.