facebook server side login results in blank page

Question

i recently made a test app in facebook, the app is a website app and i only need user login so that i can access user info from within the app using the php sdk, when i first tested it, the login process works perfectly, the problem is, when i reach the test page, it is completely blank, whereas i expect it to echo: HELLO NAME, where "NAME" would be my name, here's the code, i won't post the app id, secret,etc, as those certainly work, due to the login process being fine:

   $app_id = "xxxxxxxxxxxx";
   $app_secret = "xxxxxxxxxxxxxxxxxxxxxx";
   $my_url = "http://www.anithro.com/anithroproject/login.php/";
    session_start();
    $code = $_REQUEST["code"];

   if(empty($code)) {
 // Redirect to Login Dialog
   $_SESSION['state'] = md5(uniqid(rand(), TRUE)); // CSRF protection
 $dialog_url = "https://www.facebook.com/dialog/oauth?client_id=" 
   . $app_id . "&redirect_uri=" . urlencode($my_url) . "&state="
   . $_SESSION['state'] . "&scope=user_birthday,read_stream";

 echo("<script> top.location.href='" . $dialog_url . "'</script>");
   if($_SESSION['state'] && ($_SESSION['state'] === $_REQUEST['state'])) {
 // state variable matches
   $token_url = "https://graph.facebook.com/oauth/access_token?"
   . "client_id=" . $app_id . "&redirect_uri=" . urlencode($my_url)
   . "&client_secret=" . $app_secret . "&code=" . $code;

 $response = file_get_contents($token_url);
 $params = null;
 parse_str($response, $params);
 $_SESSION['access_token'] = $params['access_token'];
 $graph_url = "https://graph.facebook.com/me?access_token=" 
   . $_SESSION['access_token'];

 $user = json_decode(file_get_contents($graph_url));
 echo("Hello " . $user->name);
   }
   else {
     echo("The state does not match. You may be a victim of CSRF.");
     }
   }

i have followed the code to the letter, why can't i access the user variables?thanks in advance.you can try visiting the url i've given and see, it's just blank.

Answer 1

Did you test the access_token you are using if it is authenticated? You can use this for debugging tools: https://developers.facebook.com/tools/

You can also try this link: https://github.com/facebook/facebook-php-sdk The PHP SDK here uses a class to get the basic info of the user that logs in. Check the example folder.