实际上这是我函数中的私有函数。php可以工作，但是：我经常在第一次加载时收到服务器的错误500，通常它在重新加载页面后呈现。

## change the sorting order on archive pages: order archive by title
add_action( \'pre_get_posts\', \'gpsp_change_sort_order\');
function gpsp_change_sort_order($query) {
  if(is_archive() && $query->is_main_query()) :
    $query->set( 
      \'meta_query\',
      array(
        \'relation\' => \'OR\',
        array( \'key\' => \'ausgabe\',  \'value\' => \'\', \'compare\' => \'EXISTS\', \'type\' => \'NUMERIC\' ),
        array( \'key\' => \'position\', \'value\' => \'\', \'compare\' => \'EXISTS\', \'type\' => \'NUMERIC\' )
      ));
    $query->set( \'orderby\', \'meta_value position\' );
    $query->set( \'meta_key\', \'ausgabe\' );
    $query->set( \'order\', \'ASC\' );
  endif;    
};