wp_autosave_post_revisioned_meta_fields

WordPress Version: 6.4

/**
 * Autosave the revisioned meta fields.
 *
 * Iterates through the revisioned meta fields and checks each to see if they are set,
 * and have a changed value. If so, the meta value is saved and attached to the autosave.
 *
 * @since 6.4.0
 *
 * @param array $new_autosave The new post data being autosaved.
 */
function wp_autosave_post_revisioned_meta_fields($new_autosave)
{
    /*
     * The post data arrives as either $_POST['data']['wp_autosave'] or the $_POST
     * itself. This sets $posted_data to the correct variable.
     *
     * Ignoring sanitization to avoid altering meta. Ignoring the nonce check because
     * this is hooked on inner core hooks where a valid nonce was already checked.
     */
    $posted_data = isset($_POST['data']['wp_autosave']) ? $_POST['data']['wp_autosave'] : $_POST;
    $post_type = get_post_type($new_autosave['post_parent']);
    /*
     * Go thru the revisioned meta keys and save them as part of the autosave, if
     * the meta key is part of the posted data, the meta value is not blank and
     * the the meta value has changes from the last autosaved value.
     */
    foreach (wp_post_revision_meta_keys($post_type) as $meta_key) {
        if (isset($posted_data[$meta_key]) && get_post_meta($new_autosave['ID'], $meta_key, true) !== wp_unslash($posted_data[$meta_key])) {
            /*
             * Use the underlying delete_metadata() and add_metadata() functions
             * vs delete_post_meta() and add_post_meta() to make sure we're working
             * with the actual revision meta.
             */
            delete_metadata('post', $new_autosave['ID'], $meta_key);
            /*
             * One last check to ensure meta value not empty().
             */
            if (!empty($posted_data[$meta_key])) {
                /*
                 * Add the revisions meta data to the autosave.
                 */
                add_metadata('post', $new_autosave['ID'], $meta_key, $posted_data[$meta_key]);
            }
        }
    }
}