Next.js API Routes Building Server-Side Functionality

The pages/api/users.js file defines an API route accessible at /api/users. The handler function accepts two parameters: req (a NextApiRequest object representing the HTTP request) and res (a NextApiResponse object for the HTTP response). For GET requests, it returns a user list (hardcoded here, but typically queried from a database in practice). For POST requests, it accepts user data from the request body, simulates adding it to a database, and returns a success message. For unsupported methods, it returns a 405 Method Not Allowed error with allowed methods specified. Next.js API Routes enable the creation of standalone server-side functionality within a Next.js application, capable of handling HTTP requests and returning JSON data or other responses. API routes reside in the pages/api directory, with each file mapping to a specific API endpoint.

import type { NextApiRequest, NextApiResponse } from 'next';

// Get user list
export default async function handler(req: NextApiRequest, res: NextApiResponse) {
  if (req.method === 'GET') {
    const users = [
      { id: 1, name: 'User 1' },
      { id: 2, name: 'User 2' },
      { id: 3, name: 'User 3' },
    ];

    res.status(200).json(users);
  } else if (req.method === 'POST') {
    const user = req.body;

    // Simulate database connection
    // await addUserToDatabase(user);

    res.status(201).json({ message: 'User added successfully.' });
  } else {
    res.setHeader('Allow', ['GET', 'POST']);
    res.status(405).end(`Method ${req.method} Not Allowed`);
  }
}

1. The pages/api/users.js file defines an API route accessible at /api/users.
2. The handler function accepts two parameters: req (a NextApiRequest object representing the HTTP request) and res (a NextApiResponse object for the HTTP response).
3. For GET requests, it returns a user list (hardcoded here, but typically queried from a database in practice).
4. For POST requests, it accepts user data from the request body, simulates adding it to a database, and returns a success message.
5. For unsupported methods, it returns a 405 Method Not Allowed error with allowed methods specified.