WP Redis Group Cache usage example - see the comment section for description

group-caching-demo.php

---- page.php ---
<?php
/**
 * This is a demo for using the WP Redis Group Cache.
 */

/**
 * A demo DustPress model class.
 */
class Page extends \DustPress\Model {

    /**
     * The current page id.
     *
     * @var int
     */
    protected $post_id;

    /**
     * The group key for our template type.
     *
     * @var string
     */
    protected $group_key;

    /**
     * Get the main content of the page.
     *
     * @return array|bool|mixed|null|object
     */
    public function Content() {
        // Class functions are run in top-down order thus we can initialize the id here.
        $this->post_id = get_the_ID();

        // Lets define the cache keys.
        // The group key is defined by the template class name which is 'Page'.
        $this->group_key = get_called_class();
        // Cache key for this function consists of the post id and the function name.
        $cache_key = $this->post_id . '/' . __FUNCTION__;

        // Maybe get from cache...
        $content = wp_cache_get( $cache_key, $this->group_key );
        if ( $content ) {
            // Return the cached data for our view.
            return $content;
        }

        $content = \DustPress\Query::get_acf_post( $this->post_id );

        // Store the data for a week.
        wp_cache_set( $cache_key, $content, $this->group_key, WEEK_IN_SECONDS );

        // Return the fetched data for our view.
        return $content;
    }

    /**
     * Get the sidebar content for the page.
     */
    public function Sidebar() {

        // Same as above...
        $cache_key = $this->post_id . '/' . __FUNCTION__;
        $data = wp_cache_get( $cache_key, $this->group_key );
        if ( $data ) {
            return $data;
        }

        // Lets fetch 10 newest pages for a sidebar link list.
        $pages = get_pages( [
            'number'      => 10,
            'exclude'     => $this->post_id,
            'sort_column' => 'post_modified',
            'sort_order'  => 'desc',
        ] );

        // Store the data for a week.
        wp_cache_set( $cache_key, $pages, $this->group_key, WEEK_IN_SECONDS );

        // Return the fetched data for our view.
        return $pages;
    }
}

?>

---- cache.php ---
<?php
/**
 * Cache functions
 * ---------------
 * Currently we flush all function caches for all 'Page' models
 * on 'save_post' hook when the saved post is a page.
 */

/**
 * Clear cache by cache groups.
 *
 * @param array $groups    Cache groups.
 */
function flush_cache( $groups ) {
    if ( ! class_exists( '\Geniem\GroupCache' ) ) {
        return;
    }

    foreach ( $groups as $group ) {
        \Geniem\GroupCache::delete_group( $group );
    }
}

/**
 * Flushes group caches save_post hook.
 *
 * @param int $post_id Post ID.
 */
function flush_page_caches( $post_id = 0 ) {
    // If the post is not a saved page, return.
    if ( 0 === $post_id ||
         get_post_status( $post_id ) === 'auto-draft' ||
         get_post_type( $post_id ) !== 'page' ) {
        return;
    }

    // Here we could define multiple groups.
    $groups = [
        'Page'
    ];

    // Flush all defined groups.
    flush_cache( $groups );
}
add_action( 'save_post', 'flush_page_caches' );

?>