通常无法检查元数据是否更新，但您可以使用updated_postmeta 和added_post_meta 获得类似的功能。请查看以下代码-

add_action( \'updated_postmeta\', \'the_dramatist_updated_postmeta\', 10, 4 );
add_action( \'added_post_meta\', \'the_dramatist_updated_postmeta\', 10, 4 );
function the_dramatist_updated_postmeta(
    $meta_id,
    $object_id,
    $meta_key,
    $meta_value
) {
    // check meta key with $meta_key parameter
    if ( \'your_meta_key\' !== $meta_key ) {
        return;
    }
    // better check with the exiting data with the $meta_value to check if the data is updated or not.
    // then do what you want to do with the data
}