php sdk - get user_id without app authorization

Question

is it possible to get the user_id from the facebook user without requiring the user to authorize the app?

I just want to get the user_id to identify the user.. the user dont require the id if the user dont want to use the app.. but every user in facebook is allowed to vote to user solutions.. therefore i need the user id to identify the user.. i dont want to write something in the user name or something else..

http://developers.facebook.com/docs/authentication/signed_request/

here i read that the user_id should be returned.. but i removed the app permission for my user.. and now i'am missing the user_id in the signed request..

please somebody help

Answer 1

is it possible to get the user_id from the facebook user without requiring the user to authorize the app?

No.

Answer 2

If you have the email you could do:

$facebook->api('/me?fields=email');

it will return:

Array
(
    [email] => xxx
    [id] => 934579348

)