API Design Patterns

RESTful APIs, OpenAPI, error handling, rate limiting, and API versioning.

Overview

Well-designed APIs provide consistent and reliable interfaces.

Key Concepts

• RESTful Design — Resource-based URLs
• OpenAPI/Swagger — API documentation
• Error Handling — Consistent error responses
• Rate Limiting — Prevent abuse
• API Versioning — Maintain backward compatibility

Code Examples

// app/api/v1/users/route.js
import { NextResponse } from 'next/server';

export async function GET(request) {
  try {
    const users = await db.users.findMany();
    return NextResponse.json({ data: users });
  } catch (error) {
    return NextResponse.json(
      { error: { code: 'INTERNAL_ERROR', message: 'Failed to fetch users' } },
      { status: 500 }
    );
  }
}

export async function POST(request) {
  try {
    const body = await request.json();
    
    // Validation
    const errors = validateUser(body);
    if (errors.length > 0) {
      return NextResponse.json(
        { error: { code: 'VALIDATION_ERROR', details: errors } },
        { status: 400 }
      );
    }

    const user = await db.users.create({ data: body });
    return NextResponse.json({ data: user }, { status: 201 });
  } catch (error) {
    return NextResponse.json(
      { error: { code: 'INTERNAL_ERROR', message: 'Failed to create user' } },
      { status: 500 }
    );
  }
}

// Rate limiting middleware
const rateLimit = new Map();

export function middleware(request) {
  const ip = request.ip;
  const now = Date.now();
  const windowMs = 60 * 1000; // 1 minute
  const maxRequests = 100;

  if (!rateLimit.has(ip)) {
    rateLimit.set(ip, []);
  }

  const requests = rateLimit.get(ip).filter(timestamp => now - timestamp < windowMs);
  requests.push(now);
  rateLimit.set(ip, requests);

  if (requests.length > maxRequests) {
    return NextResponse.json(
      { error: 'Too many requests' },
      { status: 429 }
    );
  }

  return NextResponse.next();
}

Practice

Build a RESTful API with proper error handling and rate limiting.