My approach is a little different.
URL, , . Facebook Facebook Facebook:
"", signed_request , . JSON id ( ) (SOURCE)
, ( $facebook):
$page_id = "";
$sr = $facebook->getSignedRequest();
if($page = $sr['page']) {
$page_id = $page['id'];
}
$page_id , , , $_GET. Switch - , , , , , , , , .:)
. () , , .