Facebook API实时更新与USER表的问题

Question

我正在用户表中的 online_presence 字段使用Facebook API 实时更新，这是我使用的php代码。

参考： https://developers.facebook.com/blog/post/2012/01/31/how-to--subscribing-to-data-changes-using-the-real-time-updates-api/，

https://developers.facebook.com/docs/graph-api/real-time-updates/     

$con=mysqli_connect("host","username","password","db_name");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }
mysqli_query($con,"INSERT INTO  `db_name`.`table_name` (`value`) VALUES ('Test');");

  $verify_token = 'spydertest';

  if ($_SERVER['REQUEST_METHOD'] == 'GET' && isset($_GET['hub_mode'])
    && $_GET['hub_mode'] == 'subscribe' && isset($_GET['hub_verify_token'])
    && $_GET['hub_verify_token'] == $verify_token) {
      echo $_GET['hub_challenge'];
mysqli_query($con,"INSERT INTO  `db_name`.`table_name` (`value`) VALUES ('Subscription Test');");

  } else if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $post_body = file_get_contents('php://input');
    $obj = json_decode($post_body, true);
    // $obj will contain the list of fields that have changed
mysqli_query($con,"INSERT INTO  `db_name`.`table_name` (`value`) VALUES ('$post_body');");
  }
mysqli_close($con);

?>

这是我的Facebook应用程序的实时更新设置

订阅测试成功，实时更新也适用于好友字段，并在我添加或删除好友时收到回调，但 online_presence 字段无法正常工作我改变了用户或朋友的存在。