Pagination, filtering, and sorting in REST APIs

Pagination, Filtering, and Sorting

Production APIs never return entire datasets. Pagination, filtering, and sorting are controlled through query parameters.

Implementing all three

let products = Array.from({ length: 50 }, (_, i) => ({
  id: i + 1,
  name: `Product ${i + 1}`,
  category: i % 2 === 0 ? 'shoes' : 'bags',
  price: Math.round(Math.random() * 200) + 10
}));

app.get('/products', (req, res) => {
  let { page = 1, limit = 10, sort, category } = req.query;
  page = parseInt(page);
  limit = parseInt(limit);

  let result = [...products];

  // Filter
  if (category) result = result.filter(p => p.category === category);

  // Sort
  if (sort) result.sort((a, b) => a[sort] > b[sort] ? 1 : -1);

  // Paginate
  const total = result.length;
  const start = (page - 1) * limit;
  const data = result.slice(start, start + limit);

  res.json({
    data,
    meta: { page, limit, total, totalPages: Math.ceil(total / limit) }
  });
});

Always validate and cap the limit parameter: limit = Math.min(parseInt(limit), 100). Never let clients request unlimited records. Include meta.total and meta.totalPages so clients can render pagination UI without a second request.