如何让WordPress的搜索在搜索的时候也支持去查询文章的评论中是否包含搜索关键词？

如果您的搜索使用的是WordPress默认的搜索的话，可以把下面的代码放到您的functions.php中来实现，但是可能对于自定义搜索不起作用。

/** 
* WordPress搜索文章支持查询评论 
* https://www.wpshequ.cn 
*/ 
function sort_by_sticky( $query ) {
    if($query->is_search && !empty($query->query['paged'])){
        $search = htmlspecialchars($query->query['s']);
        global $wpdb;
        $querystr = "
        select $wpdb->posts.ID
                   from $wpdb->posts
        left join $wpdb->comments
                   on $wpdb->comments.comment_post_ID = $wpdb->posts.ID
                   where $wpdb->posts.post_content like \"%$search%\"
                   or $wpdb->comments.comment_content like \"%$search%\"
                   or $wpdb->posts.post_title like \"%$search%\"
                   or $wpdb->comments.comment_author like \"%$search%\"
                   group by $wpdb->posts.ID
        ";
        $match_posts = $wpdb->get_results($querystr, OBJECT);
        $query->set('s', '');
        $match_post_ids = array();
        foreach($match_posts as $match_post){
            $match_post_ids[] = $match_post->ID;
        }
        $query->set('post__in', $match_post_ids);
    }
}
add_action( 'pre_get_posts', 'sort_by_sticky' );