Saving Article's draft in CakePHP 2

Article.php

<?php

/* For this whole thing to work, you'll need at least these fields in your
 * articles table:
 *
 * - id (article id)
 * - parent_id (to link drafts to parent article)
 * - slug (for friendly URLs usually)
 * - title (obviously)
 * - content (obviously)
 * - status (published/draft/etc)
 */


/* In the bootstrap.php */

define('ARTICLE_STATUS_DRAFT', 'draft');


/* In the Article model */

	/**
	 * beforeSave() callback
	 * 
	 * Before we overwrite an existing article, fetch its original state and 
	 * save it temporarily.  We'll save it permanently in the afterSave().
	 * 
	 * @param array $options Options
	 * @return boolean True if we should proceed with save(), false otherwise.
	 */
	public function beforeSave($options = array()) {
		if (!empty($this->data['Article']['id'])) {
			$article = $this->findById($this->data['Article']['id']);
			$article['Article']['status'] = ARTICLE_STATUS_DRAFT; 
			$article['Article']['parent_id'] = $this->data['Article']['id'];
			$article['Article']['id'] = null;
			$this->draftData = $article;
		}
		return true;
	}

	/**
	 * afterSave() callback
	 * 
	 * If we just saved a pre-existing record, grab the previous state of it
	 * and make a permanent copy
	 * 
	 * @param boolean $created True if new record, false otherwise
	 * @param array $options Options
	 * @return void
	 */
	public function afterSave($created, $options = Array()) {
		if (!$created && !empty($this->draftData)) {
			$newModel = clone $this;	
			$newModel->clear();
			$newModel->create();
			$newModel->save($this->draftData);
		}
	}


        /*
         * Get article drafts
         * 
         * @param numeric $id ID of the article
         * @param numeric $limit (Optionally) Limit on how many drafts to get
         * @return array
         */
        public function getDrafts($id, $limit = 20) {
                $result = $this->find('all', array(
                        'conditions' => array(
                                'Article.parent_id' => $id,
                        ),
                        'order' => 'Article.id DESC',
                        'limit' => $limit,
                ));
                // If we haven't found any drafts, there is a possibility
                // that we are looking at a draft currently.  So we might
                // try to fetch the siblings.
                if (empty($result)) {
                        $article = $this->findById($id);
                        //Articles with no parent_id have no history or drafts
                        if ($article['Article']['parent_id'] !== null) {
                                $result = $this->find('all', array(
                                        'conditions' => array(
                                                'Article.parent_id' => $article['Article']['parent_id'],
                                                'Article.id <>' => $id,
                                        ),
                                        'order' => 'Article.id DESC',
                                        'limit' => $limit,
                                ));
                        }
                }

                return $result;
	}


	/**
	 * Diff two given articles
	 *
	 * This requires the FineDiff library from:
	 * http://www.raymondhill.net/finediff/
	 * 
	 * @param numeric $from ID of the original article
	 * @param numeric $to ID of the modified article
	 * @return array
	 */
	public function diff($from, $to) {
		$result = '';
		
		App::uses('FineDiff', 'Articles.Lib');
		
		$src = $this->findById($from);
		$dst = $this->findById($to);

		$fields = array_keys($src['Article']);
		$allowedFields = array('slug', 'title', 'content');
		foreach ($fields as $field) {
			if (!in_array($field, $allowedFields)) {
				continue;
			}
			$fineDiff = new FineDiff($src['Article'][$field], $dst['Article'][$field]);
			$result[$field] = $fineDiff->renderDiffToHTML();
		}

		return $result;
	}
}