我有一个功能，可以从the_content 并将其保存为一个名为audio_url 然后从中删除mp3链接the_content. 我需要帮助的是如果the_content 具有新的mp3链接，需要使用新的mp3链接更新自定义字段。我尝试了很多选项，它要么不会更新，要么会删除写入自定义字段的数据

我的功能代码：

function save_url_link( $post_id, $post ){
// only works if the post is an audio post format
if ( has_post_format(\'audio\', $post_id)) {
// look for either http or https mp3, m4a, ogg, wav or wma files
$pattern = "/(http|https):\\/\\/.*\\/(.*)\\.(mp3|m4a|ogg|wav|wma)/";
// php the removes all except the mp3 link
preg_match_all($pattern,$post->post_content,$matches);
// saves the mp3 link to a string
$audio_raw = $matches[0][0];
// check if meta field is empty
if (get_post_meta( $post_id, \'audio_url\', true ) == \'\') {
  // update the meta field
  update_post_meta( $post_id, \'audio_url\', $audio_raw ); 
  // removes the save action
  remove_action(\'save_post\', \'save_url_link\', 10, 2);
  // update the content without the mp3 link
  wp_update_post(array(\'ID\' => $post_id,\'post_excerpt\'=>$audio_raw,\'post_content\' => preg_replace(\'/(http|https):\\/\\/.*\\/(.*)\\.(mp3|m4a|ogg|wav|wma)/\', "", $post->post_content)));  
// close and save
};}}
add_action( \'save_post\', \'save_url_link\', 10, 2 );