Bits of .NET

Basic Usage

// Get from cache
$data = get_transient('my_cached_data');

// Not in cache? Get fresh data
if (false === $data) {
    $data = expensive_api_call();
    
    // Store for 1 hour (3600 seconds)
    set_transient('my_cached_data', $data, HOUR_IN_SECONDS);
}

return $data;

Real Example: Cache WooCommerce Products

function get_featured_products() {
    $transient_key = 'featured_products_v1';
    $products = get_transient($transient_key);
    
    if (false === $products) {
        // Expensive query
        $args = array(
            'post_type' => 'product',
            'posts_per_page' => 10,
            'meta_query' => array(
                array('key' => '_featured', 'value' => 'yes')
            )
        );
        $products = new WP_Query($args);
        
        // Cache for 12 hours
        set_transient($transient_key, $products, 12 * HOUR_IN_SECONDS);
    }
    
    return $products;
}

// Delete cache when product updated
add_action('save_post_product', function() {
    delete_transient('featured_products_v1');
});

“Homepage was hitting Instagram API 50 times per minute. Added transient cache (30 min expiry). Server load dropped 90%. Zero plugins.”