如果附件附加到帖子，则该帖子将被确定为“post\\u parent”。

因此，如果您在attachement模板中（attachment.php、image.php等）：

while ( have_posts() ) {
  the_post();
  // Get parent id of current post (get_the_ID() gets id of current post,
  // whicdh is the attachement, as we are in the attachment template)
  $parent_id = wp_get_post_parent_id( get_the_ID() );

}

while ( have_posts() ) {
  the_post();
  global $post;
  $parent_id = $post->post_parent;
}

  if( $parent_id ) {
      // parent post has been found, get its permalink
      $parent_url = get_permalink( $parent_id );

       ?>
       <a href="<?php echo $parent_url; ?>">
           <?php _e(\'Go to parent post\', \'textdomain\'); ?>
       <a/>
       <?php
       echo get_post_meta( $parent_id, \'custom-field\', true );
  }