我不确定我的做法是否正确，似乎有很多人这样做，但从模板中的查询到函数，都有完全不同的方法，所以我不确定该走哪条路。

我有一个自定义的帖子类型（业务），其中包含特色帖子，每个帖子都有一个“featured\\u listing”post\\u meta，它可以是空的，也可以是附加到帖子的“featured listing”值**。我想在搜索结果和类别中显示那些没有空post\\u meta值的帖子。

**请注意值的-而不是\\u0。

这是我认为可能有效的方法，但我开始认为我找错了方向。

// Order posts by meta data
function custom_special_sort( $query ) {
    //is this the main query and is this post type of post
    if ( $query->is_main_query() && $query->is_post_type( \'business\' ) ) {
        //Do a meta query
        $query->get_post_meta(get_the_ID(), "featured_listing", TRUE);

        //sort by a meta value
        $query->set( \'orderby\', \'featured_listing\' );
        $query->set( \'order\', \'ASC\' );
    }
}
add_action( \'pre_get_posts\', \'custom_special_sort\' );

我也试着稍微改变一下，如下所示。但可以提供一些指导，说明为什么它不起作用，或者我是否做得正确：

    function custom_special_sort( $query ) {
    // Check this is main query and other conditionals as needed
    if ( $query->is_main_query() && $query->is_post_type( \'business\' ) ) {
        $query->set( 
          \'meta_query\', 
          array( 
            array(
              \'key\' => \'featured_listing\',
              \'value\' => \'featured-listing\',
              \'orderby\' => \'featured_listing\',
              \'order\' => \'DESC\'  
            )
          )
        );
    }
  }
add_action( \'pre_get_posts\' , \'custom_special_sort\' );

if (is_post_type_archive(\'business\')) {...}

if ($query->get(\'post_type\') == \'business\') {...}

function custom_special_sort( $query ) {

    // if is this the main query and is this post type of business
    if ( $query->is_main_query() && is_post_type_archive( \'business\' ) ) {

        // order results by the meta_key \'featured_listing\'
        $query->set( \'meta_key\', \'featured_listing\' );
        $query->set( \'orderby\', \'featured_listing\' );
        $query->set( \'order\', \'DESC\' );
    }
}
add_action( \'pre_get_posts\', \'custom_special_sort\' );

function custom_special_sort( $query ) {

    // if is this the main query and is this post type of business

    if ( ($query->is_main_query() && is_post_type_archive(\'business\')) || (is_main_query() && is_tax (\'location\')) ) {

        // order results by the meta_key \'featured_listing\'
       $query->set( \'meta_key\', \'featured_listing\' );
        $query->set( \'orderby\', \'featured_listing\' );
        $query->set( \'order\', \'DESC\' );
    }
}
add_action( \'pre_get_posts\', \'custom_special_sort\' );