Facebook PHP SDK: getAccessToken not correct on refresh - facebook

Question

On my facebook app, I'm logging a user in using the Javascript SDK.
If OK, I redirect him to this PHP page (designed to illustrate my problem):
test.php:
<?php
include('config.php');
require('phpsdk.php');
$access_token = $facebook->getAccessToken();
echo $access_token;
echo "<br /><br />";
$user = $facebook->getUser();
echo $user;
?>
(phpsdk.php handels the PHP SDK initiation)
Accessing test.php the FIRST time, returns a valid access token and the ID of the logged user.
However, when I refresh the page, the access token becomes of the type appID|appSecret.
The user is still logged in: getUser still returns the correct user ID.
Anyone knows what's causing this?

Answer 1

Clearing the Facebook Session with php sdk in redirect when user logs out.
Logout.php redirect user and use sdk to clear session data.
example redirect url. yourdomain.com/Logout.php?destroy=true
refer to: https://developers.facebook.com/docs/reference/php/facebook-destroySession/
<?php
session_start();
require './src/facebook.php';
$facebook = new Facebook(array(
'appId' => 'appID',
'secret' => 'appSecret',
'cookie' => true, // enable optional cookie support
));
if(isset($_GET['destroy'])){
$facebook->destroySession();
}
?>

Answer 2

It is not recommended to call getAccessToken(); over and over the way you described.
You should try first to see if the token is in the browser as a session and if not then try to use the SDK to find or request it.
Check browser for a user, if no user call sdk for user, if still null or 0 auth or reauth.
If user, check browser for access_token, if no token call sdk for token.
<?php
session_start();
include('config.php');
require('phpsdk.php');
// need to replace Your_App_ID and YourAppId with your applications id.
$facebook = new Facebook(array(
'appId' => 'Your_App_ID',
'secret' => 'Your_App_Secret',
'cookie' => true, // enable optional cookie support
));
if(isset($_SESSION['fb_YourAppId_user_id'])){
$user = $_SESSION['fb_YourAppId_user_id'];
}else{
$user = $facebook->getUser();
}
if($user){
if(isset($_SESSION['fb_YourAppId_access_token'])){
$access_token = $_SESSION['fb_YourAppId_access_token'];
}else{
$access_token = $facebook->getAccessToken();
}
}
echo $user;
echo "<br /><br />";
echo $access_token;
?>