Pressbooks\Modules\Import\WordPress\Wxr::importMetaBoxes PHP Метод

    protected function importMetaBoxes($pid, $p)
    {
        // List of meta data keys that can support multiple values:
        $multiple = array('pb_contributing_authors' => true, 'pb_keywords_tags' => true, 'pb_bisac_subject' => true);
        // Clear old meta boxes
        $metadata = get_post_meta($pid);
        foreach ($metadata as $key => $val) {
            // Does key start with pb_ prefix?
            if (0 === strpos($key, 'pb_')) {
                delete_post_meta($pid, $key);
            }
        }
        // Import post meta
        foreach ($p['postmeta'] as $meta) {
            if (0 === strpos($meta['key'], 'pb_')) {
                if (isset($multiple[$meta['key']])) {
                    // Multi value
                    add_post_meta($pid, $meta['key'], $meta['value']);
                } else {
                    // Single value
                    if (!add_post_meta($pid, $meta['key'], $meta['value'], true)) {
                        update_post_meta($pid, $meta['key'], $meta['value']);
                    }
                }
            }
        }
    }