API Pagination
Implement scalable pagination strategies for handling large datasets efficiently.
Pagination Strategies
| Strategy | Best For | Performance |
|---|---|---|
| Offset/Limit | Small datasets, simple UI | O(n) |
| Cursor | Infinite scroll, real-time | O(1) |
| Keyset | Large datasets | O(1) |
Offset Pagination
app.get('/products', async (req, res) => {
const page = parseInt(req.query.page) || 1;
const limit = Math.min(parseInt(req.query.limit) || 20, 100);
const offset = (page - 1) * limit;
const [products, total] = await Promise.all([
Product.find().skip(offset).limit(limit),
Product.countDocuments()
]);
res.json({
data: products,
pagination: {
page,
limit,
total,
totalPages: Math.ceil(total / limit)
}
});
});Cursor Pagination
app.get('/posts', async (req, res) => {
const limit = 20;
const cursor = req.query.cursor;
const query = cursor
? { _id: { $gt: Buffer.from(cursor, 'base64').toString() } }
: {};
const posts = await Post.find(query).limit(limit + 1);
const hasMore = posts.length > limit;
if (hasMore) posts.pop();
res.json({
data: posts,
nextCursor: hasMore ? Buffer.from(posts[posts.length - 1]._id).toString('base64') : null
});
});Response Format
{
"data": [...],
"pagination": {
"page": 2,
"limit": 20,
"total": 150,
"totalPages": 8
},
"links": {
"first": "/api/products?page=1",
"prev": "/api/products?page=1",
"next": "/api/products?page=3",
"last": "/api/products?page=8"
}
}Best Practices
- Set reasonable max limits (e.g., 100)
- Use cursor pagination for large datasets
- Index sorting fields
- Avoid COUNT queries when possible
- Never allow unlimited page sizes