Facebook class using cakePHP session. based on Facebook PHP SDK (v.3.2.2) https://github.com/facebook/facebook-php-sdk

CakeFacebook.php

<?php
/**
 * Copyright 2013 mogya.
 * Copyright 2011 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License. You may obtain
 * a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

require_once "base_facebook.php";

/**
 * Extends the BaseFacebook class with the intent of using
 * PHP sessions to store user ids and access tokens.
 */
class CakeFacebook extends BaseFacebook
{
  /**
   * Identical to the parent constructor, except that
   * we start a CakePHP session to store the user ID and
   * access token if during the course of execution
   * we discover them.
   *
   * @param Array $config the application configuration. 
   * "sharedSession" is not supported.
   * @see BaseFacebook::__construct in facebook.php
   */
  public function __construct($config) {
    if (!CakeSession::started()) {
      CakeSession::start();
    }
    parent::__construct($config);
  }

  protected static $kSupportedKeys =
    array('state', 'code', 'access_token', 'user_id');

  /**
   * Provides the implementations of the inherited abstract
   * methods.  The implementation uses CakePHP CakeSession.
   */
  protected function setPersistentData($key, $value) {
    if (!in_array($key, self::$kSupportedKeys)) {
      self::errorLog('Unsupported key passed to setPersistentData.');
      return;
    }

    $session_var_name = $this->constructSessionVariableName($key);
    CakeSession::write($session_var_name,$value);
  }

  protected function getPersistentData($key, $default = false) {
    if (!in_array($key, self::$kSupportedKeys)) {
      self::errorLog('Unsupported key passed to getPersistentData.');
      return $default;
    }

    $session_var_name = $this->constructSessionVariableName($key);
    return CakeSession::check($session_var_name) ?
      CakeSession::read($session_var_name) : $default;
  }

  protected function clearPersistentData($key) {
    if (!in_array($key, self::$kSupportedKeys)) {
      self::errorLog('Unsupported key passed to clearPersistentData.');
      return;
    }

    $session_var_name = $this->constructSessionVariableName($key);
    CakeSession::delete($session_var_name);
  }

  protected function clearAllPersistentData() {
    foreach (self::$kSupportedKeys as $key) {
      $this->clearPersistentData($key);
    }
  }

  protected function constructSessionVariableName($key) {
    $parts = array('fb', $this->getAppId(), $key);
    return implode('_', $parts);
  }
}