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In this case study, we will design and develop a RESTful API for an online store. This API will allow clients to interact with the store's resources, such as products, categories, and orders. We will cover the following aspects:

API Requirements and Specifications
Designing the API
Developing the API
Testing the API
Conclusion

API Requirements and Specifications

Functional Requirements

Products: Clients should be able to view, add, update, and delete products.
Categories: Clients should be able to view and manage product categories.
Orders: Clients should be able to create and view orders.

Non-Functional Requirements

Security: The API should implement authentication and authorization.
Performance: The API should be optimized for performance.
Documentation: The API should be well-documented for ease of use.

Designing the API

Resources and URIs

Products: /products
Categories: /categories
Orders: /orders

HTTP Methods

Resource	GET	POST	PUT	DELETE
/products	List products	Create product	Update product	Delete product
/categories	List categories	Create category	Update category	Delete category
/orders	List orders	Create order	-	-

Example URIs

Get all products: GET /products
Get a single product: GET /products/{id}
Create a new product: POST /products
Update a product: PUT /products/{id}
Delete a product: DELETE /products/{id}

HTTP Status Codes

200 OK: The request was successful.
201 Created: A new resource was created successfully.
400 Bad Request: The request was invalid.
401 Unauthorized: Authentication is required.
404 Not Found: The requested resource was not found.
500 Internal Server Error: An error occurred on the server.

Developing the API

Setting Up the Development Environment

We will use Node.js and Express.js for this case study. Ensure you have Node.js installed on your machine.

# Initialize a new Node.js project
npm init -y

# Install Express.js
npm install express

Creating a Basic Server

Create a file named server.js and set up a basic Express server.

const express = require('express');
const app = express();
const port = 3000;

app.use(express.json());

app.get('/', (req, res) => {
  res.send('Welcome to the Online Store API');
});

app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});

Handling Requests and Responses

Create routes for handling products, categories, and orders.

const products = [];
const categories = [];
const orders = [];

// Products Routes
app.get('/products', (req, res) => {
  res.json(products);
});

app.post('/products', (req, res) => {
  const product = req.body;
  products.push(product);
  res.status(201).json(product);
});

app.put('/products/:id', (req, res) => {
  const id = req.params.id;
  const updatedProduct = req.body;
  products[id] = updatedProduct;
  res.json(updatedProduct);
});

app.delete('/products/:id', (req, res) => {
  const id = req.params.id;
  products.splice(id, 1);
  res.status(204).send();
});

// Similar routes can be created for categories and orders

Authentication and Authorization

For simplicity, we will use a basic token-based authentication.

const authMiddleware = (req, res, next) => {
  const token = req.headers['authorization'];
  if (token === 'mysecrettoken') {
    next();
  } else {
    res.status(401).send('Unauthorized');
  }
};

app.use(authMiddleware);

Error Handling

Add error handling middleware to catch and respond to errors.

app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).send('Something broke!');
});

Testing the API

Using Postman

Create a new request: Set the method to GET and the URL to http://localhost:3000/products.
Add a product: Set the method to POST, the URL to http://localhost:3000/products, and the body to JSON format with product details.
Update a product: Set the method to PUT, the URL to http://localhost:3000/products/{id}, and the body to JSON format with updated product details.
Delete a product: Set the method to DELETE and the URL to http://localhost:3000/products/{id}.

Example Requests

// POST /products
{
  "name": "Laptop",
  "price": 999.99,
  "category": "Electronics"
}

// PUT /products/0
{
  "name": "Gaming Laptop",
  "price": 1299.99,
  "category": "Electronics"
}

Conclusion

In this case study, we designed and developed a RESTful API for an online store. We covered the following key aspects:

Defined the API requirements and specifications.
Designed the API resources, URIs, and HTTP methods.
Developed the API using Node.js and Express.js.
Implemented authentication, error handling, and tested the API using Postman.

This case study provides a comprehensive example of how to design and develop a RESTful API for an online store. By following these steps, you can create a robust and scalable API for various applications.

Case Study: Online Store API