Lesson 28 • Advanced

Building Dynamic APIs 🔄

Design paginated, filterable, versioned REST APIs with proper JSON response envelopes and HATEOAS links.

What You'll Learn in This Lesson

• Offset-based pagination with meta and navigation links
• Filtering and sorting via query parameters
• API versioning strategies (URL, header, query)
• Standardized response envelopes for success and errors
• HATEOAS: self-describing APIs with hypermedia links

Note: PHP runs on a server. Our examples simulate PHP logic using JavaScript. To run real PHP, install PHP.

🎯 Real-World Analogy: Pagination is like a book's table of contents — you don't read all 500 pages at once, you pick a chapter. Versioning is like software updates — old users keep using v1 while new features go into v2. HATEOAS is like road signs — each API response tells you where you can go next, so clients don't need a map.

Pagination & Filtering

Never return all records at once — pagination divides results into manageable pages. Include metadata (total count, current page, links to next/prev) so clients can navigate efficiently. Add filtering and sorting via query parameters for flexible data retrieval.

Try It: Pagination & Filtering

Build paginated responses with meta data, filtering, and sorting

Try it Yourself »

JavaScript

// API Pagination & Filtering
console.log("=== Pagination Strategies ===");
console.log();

// Generate sample data
let products = [];
for (let i = 1; i <= 50; i++) {
  products.push({ id: i, name: "Product " + i, price: Math.floor(Math.random() * 200) + 10, category: ["electronics", "books", "clothing"][i % 3] });
}

// Offset-based pagination
function paginate(items, page = 1, perPage = 10) {
  let total = items.length;
  let totalPages = Math.ceil(total / perPage);
  let offset = (page - 1) *
...

Versioning & Response Format

API versioning lets you make breaking changes without disrupting existing clients. URL path versioning (/api/v2/users) is the most popular approach. Wrap all responses in a consistent envelope with success, data, meta, and errors fields.

Try It: Versioning & Envelopes

Version your API and build standardized success/error responses

Try it Yourself »

JavaScript

// API Versioning & Response Formats
console.log("=== API Versioning Strategies ===");
console.log();

console.log("1️⃣ URL Path Versioning (most common):");
console.log("  GET /api/v1/users  → Original format");
console.log("  GET /api/v2/users  → New format with breaking changes");
console.log();

console.log("2️⃣ Header Versioning:");
console.log("  GET /api/users");
console.log("  Accept: application/vnd.myapp.v2+json");
console.log();

console.log("3️⃣ Query Parameter:");
console.log("  GET
...

⚠️ Common Mistakes

⚠️

Returning all records — SELECT * FROM products with 100K rows crashes clients. Always paginate, default to 20-50 per page.

⚠️

Inconsistent error format — some endpoints return {error: "msg"}, others {message: "msg"}. Use one envelope format everywhere.

💡

Pro Tip: For high-traffic APIs, use cursor-based pagination instead of offset. It's faster for large datasets because it doesn't need to count/skip rows.

📋 Quick Reference — Dynamic APIs

Feature	Implementation
Pagination	?page=2&per_page=20
Filtering	?category=books&min_price=10
Sorting	?sort=price:desc
Versioning	/api/v2/resource
Envelope	{success, data, meta, errors}

🎉 Lesson Complete!

You can now build professional APIs! Next, learn to protect them with rate limiting and throttling.