正在寻找使用自定义字段将旧帖子推送到WP\\u查询中的方法。例如，我今年有10篇文章，想将过去的2篇文章重新发布到自定义rss提要。

因此，对于旧帖子，必须按照帖子日期和帖子元中的值对帖子进行排序：

new post - (post date: 2018-11-11)
new post - (post date: 2018-11-10)
old post - (post date: 2017-05-01, post-meta date: 2018-11-09)
new post - (post date: 2018-11-08)

我尝试在WP\\u查询中按2个值排序，但它不起作用

<?php
   add_filter(\'pre_get_posts\', function($query) {
        if($query->is_main_query() && $query->is_feed()) {
            $query->set(\'posts_per_rss\', 3);
            $query->set(\'post_type\', \'post\');
            $query->set(\'post_status\', \'publish\');

            $query->set(\'meta_query\', [
                \'relation\' => \'OR\',
                \'push_clause\' => [
                    \'key\' => \'is-push\',
                    \'compare\' => \'EXISTS\'
                ],
                \'exclude_clause\' => [
                    \'key\' => \'is-exclude\',
                    \'compare\' => \'NOT EXISTS\'
                ]
            ]);

            $query->set(\'orderby\', [\'push_clause\' => \'DESC\']);
        }
    });

是否有任何方法可以使用WP\\u查询实现此功能？

Update:我已经编写了纯sql查询，可以根据需要进行排序

SELECT SQL_CALC_FOUND_ROWS wp_posts.post_title, wp_posts.post_date, m.*, IFNULL(m.meta_value, wp_posts.post_date) as d
FROM wp_posts  
LEFT JOIN wp_postmeta m ON (wp_posts.ID = m.post_id AND m.meta_key = \'is-push\')
WHERE wp_posts.post_status = \'publish\' AND wp_posts.post_type = \'post\' 
ORDER BY 
     d DESC
LIMIT 10

$query = "SELECT SQL_CALC_FOUND_ROWS p.*, IFNULL(m2.meta_value, p.post_date_gmt) as zen_date
            FROM {$wpdb->posts} p
            LEFT JOIN {$wpdb->postmeta} m1 ON (p.ID = m1.post_id AND m1.meta_key = \'is-exclude\')
            LEFT JOIN {$wpdb->postmeta} m2 ON (p.ID = m2.post_id AND m2.meta_key = \'is-push\')
            WHERE p.post_type = \'post\' AND p.post_status = \'publish\' AND m1.post_id IS NULL
            GROUP BY p.ID ORDER BY zen_date DESC LIMIT 0, 50";

$posts = $wpdb->get_results($query, OBJECT);

foreach($posts as $post) {
    setup_postdata($post);

    // do something
}