当我对$parents to $parents[]

public static function get_parents($post_id = false){
        if (!$post_id){
            $post_id = get_the_ID();
        }
        if (!$post_id){
            global $wpdb;
            if ($wpdb->last_result && count($wpdb->last_result) == 1){
                $post_id = $wpdb->last_result[0]->ID;
            }
        }
        $parents[]= get_metadata(\'post\', $post_id, WPKWP::$META_CHILD, false);
        $something=count($parents);
        if (count($parents) > 0){
            return $parents;
        }
        return false;
    }

下面的代码似乎就是问题所在。如果我设置最后一行return $meta; 到return null; 错误似乎消失了。

public static function get_post_metadata($meta_value, $post_id, $meta_key, $single){
        if (is_admin()){
            return null;
        }

        remove_filter(\'get_post_metadata\', array(WPKWP::CLASS_NAME, \'get_post_metadata\'), 0);
        $child_meta = get_metadata(\'post\', $post_id, $meta_key, false);
        if (WPKWP::get_parent()){
            $parent_meta = get_metadata(\'post\', WPKWP::get_parent(), $meta_key, false);

            if (is_array($parent_meta) && is_array($child_meta)) {
                $meta = array_merge($parent_meta, $child_meta);
            } else {
                $meta = $parent_meta;
            }
        } else {
            $meta = $child_meta;
        }
        add_filter(\'get_post_metadata\', array(WPKWP::CLASS_NAME, \'get_post_metadata\'), 0, 4);
        return $meta;
    }