[FIXED] PHP facebook SDK 4.0 login error

Issue

I was looking for docs on official page but there is no anything helpful, so i build this code and it don't work.

    FacebookSession::setDefaultApplication('app-id', 'app-secret');
$helper = new \Facebook\FacebookRedirectLoginHelper('http://my-return-url');

if (isset($_SESSION['token'])) {
    $session = new FacebookSession($_SESSION['token']);
    if (!$session->validate()) {
        $session = null;
    }
} else {
    try {
        $session = $helper->getSessionFromRedirect();
    } catch(FacebookRequestException $ex) {
        die("Oops! :/");
    } catch(Exception $ex) {
        die($ex->message());
    }
}

if (isset($session)) {
    $_SESSION['token'] = $session->getToken();
    $session = new FacebookSession($session->getToken());

    $request = new FacebookRequest($session, 'GET', '/me');
    $response = $request->execute();
    $graphObject = $response->getGraphObject()->asArray();

    echo '<pre>';
    print_r($graphObject);
    echo '</pre>';
} else {
    echo '<a href="' . $helper->getLoginUrl() . '">Login</a>';
}

I think the problem is in SDK but i'm not sure. I always get this error:

Fatal error: Uncaught exception 'Facebook\FacebookSDKException' with message 'Session has expired, or is not valid for this app.' in /var/www/html/Facebook/FacebookSession.php:238 Stack trace: #0 /var/www/html/Facebook/FacebookSession.php(216): Facebook\FacebookSession::validateSessionInfo(Object(Facebook\GraphSessionInfo), 'my-app-id', 'app-secret...') #1 /var/www/html/verify.php(98): Facebook\FacebookSession->validate() #2 {main} thrown in /var/www/html/Facebook/FacebookSession.php on line 238

I also tried through incognito mode tried setting up new app but always i get this error.

Solution

I agree, FB documentations are pretty bad. Also, they are frequently changing thier SDK versions, a few days back they release v 4.0.5. Try this ->

<?php

// include required files form Facebook SDK

// added in v4.0.5
require_once( 'Facebook/FacebookHttpable.php' );
require_once( 'Facebook/FacebookCurl.php' );
require_once( 'Facebook/FacebookCurlHttpClient.php' );

// added in v4.0.0
require_once( 'Facebook/FacebookSession.php' );
require_once( 'Facebook/FacebookRedirectLoginHelper.php' );
require_once( 'Facebook/FacebookRequest.php' );
require_once( 'Facebook/FacebookResponse.php' );
require_once( 'Facebook/FacebookSDKException.php' );
require_once( 'Facebook/FacebookRequestException.php' );
require_once( 'Facebook/FacebookOtherException.php' );
require_once( 'Facebook/FacebookAuthorizationException.php' );
require_once( 'Facebook/GraphObject.php' );
require_once( 'Facebook/GraphSessionInfo.php' );

// added in v4.0.5
use Facebook\FacebookHttpable;
use Facebook\FacebookCurl;
use Facebook\FacebookCurlHttpClient;

// added in v4.0.0
use Facebook\FacebookSession;
use Facebook\FacebookRedirectLoginHelper;
use Facebook\FacebookRequest;
use Facebook\FacebookResponse;
use Facebook\FacebookSDKException;
use Facebook\FacebookRequestException;
use Facebook\FacebookOtherException;
use Facebook\FacebookAuthorizationException;
use Facebook\GraphObject;
use Facebook\GraphSessionInfo;

// start session
session_start();

// init app with app id and secret
FacebookSession::setDefaultApplication( 'xxx','yyy' );

// login helper with redirect_uri
$helper = new FacebookRedirectLoginHelper( 'http://yourwebsite.com/app/' );

// see if a existing session exists
if ( isset( $_SESSION ) && isset( $_SESSION['fb_token'] ) ) {
  // create new session from saved access_token
  $session = new FacebookSession( $_SESSION['fb_token'] );

  // validate the access_token to make sure it's still valid
  try {
    if ( !$session->validate() ) {
      $session = null;
    }
  } catch ( Exception $e ) {
    // catch any exceptions
    $session = null;
  }

} else {
  // no session exists

  try {
    $session = $helper->getSessionFromRedirect();
  } catch( FacebookRequestException $ex ) {
    // When Facebook returns an error
  } catch( Exception $ex ) {
    // When validation fails or other local issues
    echo $ex->message;
  }

}

// see if we have a session
if ( isset( $session ) ) {

  // save the session
  $_SESSION['fb_token'] = $session->getToken();
  // create a session using saved token or the new one we generated at login
  $session = new FacebookSession( $session->getToken() );

  // graph api request for user data
  $request = new FacebookRequest( $session, 'GET', '/me' );
  $response = $request->execute();
  // get response
  $graphObject = $response->getGraphObject()->asArray();

  // print profile data
  echo '<pre>' . print_r( $graphObject, 1 ) . '</pre>';

  // print logout url using session and redirect_uri (logout.php page should destroy the session)
  echo '<a href="' . $helper->getLogoutUrl( $session, 'http://yourwebsite.com/app/logout.php' ) . '">Logout</a>';

} else {
  // show login url
  echo '<a href="' . $helper->getLoginUrl( array( 'email', 'user_friends' ) ) . '">Login</a>';
}

Source

Answered By - codemode