/**
  * {@inheritdoc}
  */
 protected function getPageBy(SiteInterface $site = null, $fieldName, $value)
 {
     if ('id' == $fieldName) {
         $fieldName = 'pageId';
         $id = $value;
     } elseif (isset($this->pageReferences[$fieldName][$value])) {
         $id = $this->pageReferences[$fieldName][$value];
     } else {
         $id = null;
     }
     if (null === $id || !isset($this->pages[$id])) {
         $parameters = array($fieldName => $value);
         if ($site) {
             $parameters['site'] = $site->getId();
         }
         $snapshot = $this->snapshotManager->findEnableSnapshot($parameters);
         if (!$snapshot) {
             throw new PageNotFoundException();
         }
         $page = new SnapshotPageProxy($this->snapshotManager, $this->transformer, $snapshot);
         $this->pages[$id] = false;
         if ($page) {
             $this->loadBlocks($page);
             $id = $page->getId();
             if ($fieldName != 'id') {
                 $this->pageReferences[$fieldName][$value] = $id;
             }
             $this->pages[$id] = $page;
         }
     }
     return $this->pages[$id];
 }
 /**
  * {@inheritdoc}
  */
 public function getParents()
 {
     if (!$this->parents) {
         $parents = array();
         $snapshot = $this->snapshot;
         while ($snapshot) {
             $content = $snapshot->getContent();
             if (!$content['parent_id']) {
                 break;
             }
             $snapshot = $this->manager->findEnableSnapshot(array('pageId' => $content['parent_id']));
             if (!$snapshot) {
                 break;
             }
             $parents[] = new SnapshotPageProxy($this->manager, $this->transformer, $snapshot);
         }
         $this->setParents(array_reverse($parents));
     }
     return $this->parents;
 }