我有一个自定义的post类型“staff”，每个都作为一个自定义字段“\\u staff\\u purpose”（描述其功能）。

我想要档案馆的工作人员。php模板显示所有工作人员，按其\\u staff\\u目的排序，这样我就可以使用\\u staff\\u目的作为标题循环结果。我想要的结果如下：

ID  |   post_title    |  _staff_purpose
-----------------------------------------
1   |   Tracy Chap.   |  administrator
-----------------------------------------
2   |   John Doe.     |  teacher
-----------------------------------------
3   |   Robert Smith  |  teacher
-----------------------------------------

原始SQL应为：

SELECT * FROM `bj_posts` p

LEFT JOIN (
    SELECT post_id, meta_value as purpose
    FROM `bj_postmeta` pm 
    WHERE  `meta_key`=\'purpose\'
    ) pm ON p.ID=pm.post_id
WHERE p.`post_type`=\'staff\' AND p.`post_status`=\'publish\'
ORDER BY purpose ASC, post_title ASC

我试过这个：

add_action( \'pre_get_posts\', \'fetch_staff_people\' );

function fetch_staff_people( $query )
{

    if ( is_page_template(\'archive-staff.php\') && $query->is_main_query() )
    {
        $query->set( \'post_per_page\', \'-1\' );
        $query->set( \'meta_key\', \'_staff_purpose\' );
        $query->set(\'orderby\', \'meta_value title\'); // sort by purpose, then by staff name.
        $query->set( \'order\', \'ASC ASC\' );


        } else { 

          return;
        }

    return $query;
}

查询似乎正常，但自定义字段值未显示在循环中。

add_action( \'pre_get_posts\', \'fetch_staff_people\' );
function fetch_staff_people( $query )
{
  if ( is_post_type_archive(\'staff\') && $query->is_main_query() )
  {
    $query->set( \'post_per_page\', \'-1\' );
    $query->set( \'meta_key\', \'_staff_purpose\' );
    $query->set(\'orderby\', \'meta_value_num\'); // sort by purpose, then by staff name.
    $query->set( \'order\', \'ASC\' );
  }
}