Facebook PHP SDK - will not logout properly

Question

I've been searching for hours for the solution to this problem but can't find one that works for me. When i click "Logout" on my site the user information is still visible and the logout button is still displayed. Here is the code:

require 'facebook-php-sdk/src/facebook.php';

$facebook = new Facebook(array(
  'appId'  => 'xxxx',
  'secret' => 'xxxx',
));

// Get User ID
$user = $facebook->getUser();
var_dump($user);
if ($user) {
  try {
    // Proceed knowing you have a logged in user who's authenticated.
    $user_profile = $facebook->api('/me');
  } catch (FacebookApiException $e) {
    error_log($e);
    $user = null;
  }
}

// Login or logout url will be needed depending on current user state.

if ($_GET['logout'] == "yes") {
setcookie('fbs_'.$facebook->getAppId(), '', time()-100, '/', 'http://gno.....ment/index.php');
session_destroy();
header("Location: ".$_SERVER['PHP_SELF']."");
}

if ($user_profile) {
  $logoutUrl = $facebook->getLogoutUrl;
} else {
  $loginUrl = $facebook->getLoginUrl(array('scope' => 'email,publish_stream,user_status',
  'canvas' => 1,
  'fbconnect' => 0,
  'redirect_uri' => 'http://gno.....ment/index.php'));
}

..... .....

<?php if ($user): ?>
<h3>You</h3>
<img src="https://graph.facebook.com/<?php echo $user; ?>/picture">

<h3>Your User Object (/me)</h3>
<pre><?php print_r($user_profile); ?></pre>
<?php else: ?>
<strong><em>You are not Connected.</em></strong>
<?php endif ?>

<?php if ($user): ?>
<a href="<?php echo $logoutUrl; ?>">Logout of FB</a>
<?php else: ?>
<div>
Login using OAuth 2.0 handled by the PHP SDK:
<a href="<?php echo $loginUrl; ?>">Login with Facebook</a>
</div>
<?php endif ?>

It seems that if ($_GET['logout'] == "yes") might be the answer for me but i can't get it working. I don't know where logout is gotten from or where it is defined?

This seems to be a common issue but i can't figure it out. I'd really appreciate some help.

Answer 1

Doing it with PHP SDK is really easy, the documentation is just really awfull. You do not need to redirect to Facebook. You just have to clear the session that the Facebook class sets, there is a function for that in the Facebook base class called destroySession(). Here I'm doing it on a get.

require_once('libs/facebook.php');

$facebook = new Facebook(array(
    'appId'  => 'xxxxxx',
    'secret' => 'xxxxxx'
)); 

$facebook->destroySession();

The $facebook->getLogoutUrl() logs the user out of Facebook.