Facebook API: Logging in, but still not working - php

Question

I'm using the Facebook API connected script written in PHP (provided by Facebook). Everything works, it generates the login URL and redirects me back to the website when I'm logged in.
However, the $user variable seems to be undefined.
Have anyone experienced a similar problem? In the Facebook Apps statistics page I can see that the app has been used.
Update - The code:
<?php
$app_id = "xxxxxxxxxxxxxx";
$app_secret = "xxxxxxxxxxxxx";
$site_url = "http://xxx";
try{
include_once "src/facebook.php";
}catch(Exception $e){
error_log($e);
}
$facebook = new Facebook(array(
'appId' => $app_id,
'secret' => $app_secret
));
if($user = $facebook->getUser())
{
echo 'ok';
}
else
{
}
if($user){
//==================== Single query method ======================================
try{
// Proceed knowing you have a logged in user who's authenticated.
$user_profile = $facebook->api('/me');
}catch(FacebookApiException $e){
error_log($e);
$user = NULL;
}
//==================== Single query method ends =================================
}
if($user){
// Get logout URL
$logoutUrl = $facebook->getLogoutUrl();
}else{
// Get login URL
$loginUrl = $facebook->getLoginUrl(array(
'scope' => 'email,user_birthday,user_about_me',
'redirect_uri' => $site_url . '/auth_complete.php',
));
}
if($user){
// Proceed knowing you have a logged in user who has a valid session.
//========= Batch requests over the Facebook Graph API using the PHP-SDK ========
// Save your method calls into an array
$queries = array(
array('method' => 'GET', 'relative_url' => '/'.$user),
array('method' => 'GET', 'relative_url' => '/'.$user.'/home?limit=50'),
array('method' => 'GET', 'relative_url' => '/'.$user.'/friends'),
array('method' => 'GET', 'relative_url' => '/'.$user.'/photos?limit=6'),
);
// POST your queries to the batch endpoint on the graph.
try{
$batchResponse = $facebook->api('?batch='.json_encode($queries), 'POST');
}catch(Exception $o){
error_log($o);
}
//Return values are indexed in order of the original array, content is in ['body'] as a JSON
//string. Decode for use as a PHP array.
$user_info = json_decode($batchResponse[0]['body'], TRUE);
$feed = json_decode($batchResponse[1]['body'], TRUE);
$friends_list = json_decode($batchResponse[2]['body'], TRUE);
$photos = json_decode($batchResponse[3]['body'], TRUE);
//========= Batch requests over the Facebook Graph API using the PHP-SDK ends =====
}
?>

Answer 1

I'm not entirely sure why it worked, but I redirected the user to a page where the Javascript SDK is included (http://developers.facebook.com/docs/reference/javascript/), and now it's working!

Answer 2

The user have not authorized the app yet. Try something like this-
$user_id = $facebook->getUser();
echo $uid;
if($user_id){
try {
$user_profile = $facebook->api('/me');
} catch (FacebookApiException $e) {
error_log($e);
$user_id = null;
}
}else{
$login_url = $facebook->getLoginUrl();
echo("<br>login url=".$login_url);
};

Answer 3

An FB app of ours that previously worked for months is now experiencing the issue you speak of. $fb_user is now being returned undefined. =(

Answer 4

Update your SDK, sounds like you are hitting a certificate issue from a few weeks back.
You can find the latest version at https://github.com/facebook/facebook-php-sdk/