How to support login using a Facebook account (facebook-php-sdk-v4)

Question

I am trying to have a login facebook option for my website using the latest php version (facebook-php-sdk-v4), but I just keep getting this error by the browser:

Parse error: syntax error, unexpected T_OBJECT_OPERATOR in
/home/.../src/Facebook/FacebookSession.php on line 89

And as you should know that code (FacebookSession.php) is part of the PHP SDK V4 version I am trying to implement. (https://developers.facebook.com/docs/php/gettingstarted/4.0.0)

This is the part of the file that reports the error (I have even included it in my script but I get the same result):

$me = (new FacebookRequest(
$session, 'GET', '/me'
))->execute()->getGraphObject(GraphUser::className());

This is the full code I have put in the index.php of my website:

<?php

require_once( 'src/Facebook/FacebookSession.php' );
require_once( 'src/Facebook/FacebookRedirectLoginHelper.php' );
require_once( 'src/Facebook/FacebookRequest.php' );
require_once( 'src/Facebook/FacebookResponse.php' );
require_once( 'src/Facebook/FacebookSDKException.php' );
require_once( 'src/Facebook/FacebookRequestException.php' );
require_once( 'src/Facebook/FacebookAuthorizationException.php' );
require_once( 'src/Facebook/GraphObject.php' );

use src\Facebook\FacebookSession;
use src\Facebook\FacebookRedirectLoginHelper;
use src\Facebook\FacebookRequest;
use src\Facebook\FacebookResponse;
use src\Facebook\FacebookSDKException;
use src\Facebook\FacebookRequestException;
use src\Facebook\FacebookAuthorizationException;
use src\Facebook\GraphObject;

// start session
session_start();

// init app with app id and secret
FacebookSession::setDefaultApplication( 'xxxxxxxxxxxx','xxxxxxxxxxxxxxxxxxxxxxxxxxx' );

$helper = new FacebookRedirectLoginHelper('your redirect URL here');
$loginUrl = $helper->getLoginUrl();
// Use the login url on a link or button to redirect to Facebook for authentication

$helper = new FacebookRedirectLoginHelper();
try {
$session = $helper->getSessionFromRedirect();
} catch(FacebookRequestException $ex) {
// When Facebook returns an error
} catch(\Exception $ex) {
// When validation fails or other local issues 
}
if ($session) {
// Logged in
}
?>

Any guidance will be greatly appreciated.

Answer 1

To Run the Facebook SDK 4.0 In (PHP < 5.4.0)

Please change chaining method from all facebook page such as FacebookSession.php Example are below

// change this
$graphObject = (new FacebookRequest( $session, 'GET', '/me' ))->execute()->getGraphObject();

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

After changing the chaining method Please also changed.

// change this  
 if (session_status() !== PHP_SESSION_ACTIVE) {
      throw new FacebookSDKException(
        'Session not active, could not load state.'
      );
    }

// into this
if(session_id() === "") {
    throw new FacebookSDKException(
        'Session not active, could not load state.'
    );
}

Answer 2

the error “Parse error: syntax error, unexpected T_OBJECT_OPERATOR in…” is because the SDK v4 requires PHP version 5.4