Page Caching

Caching reduces work for repeat visitors. CodeIgniter can cache a whole rendered page for a number of seconds, and it can also cache individual data values through the cache service.

Cache a controller page

public function index()
{
    $this->cachePage(300); // 5 minutes

    return view('catalog/index', ['products' => $this->products()]);
}

Page caching is best for public, identical responses. Do not cache pages that change per user, contain CSRF tokens, or show private data.

Cache data

$cache = service('cache');

$stats = $cache->get('home_stats');
if ($stats === null) {
    $stats = $this->calculateStats();
    $cache->save('home_stats', $stats, 600);
}

Clear and invalidate

$cache->delete('home_stats');
// Or remove everything after a deployment:
cache()->clean();

Choosing a handler

File caching is simple and works on most hosts. Redis or Memcached is a better choice when multiple servers must share cached values. Set the handler in app/Config/Cache.php or through .env.

Guidelines

• Cache only data that is expensive to produce and safe to reuse.
• Include a version or key prefix so a deployment does not serve stale structures.
• Invalidate when the underlying records change.
• Avoid very long lifetimes for prices, stock, or availability.
• Test the cache-disabled path as well as the cached path.

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