ArticleData::getUserDefinedColumns PHP Method

    public function getUserDefinedColumns($p_showAll = false, $p_skipCache = false)
    {
        if (empty($this->m_articleTypeName)) {
            return array();
        }
        $cacheService = \Zend_Registry::get('container')->getService('newscoop.cache');
        $cacheKey = $cacheService->getCacheKey(array('article_type_user_defined_columns', $this->m_articleTypeName, $p_showAll), 'article_type');
        if ($cacheService->contains($cacheKey) && !$p_skipCache) {
            return $cacheService->fetch($cacheKey);
        } else {
            $articleTypeObject = new ArticleType($this->m_articleTypeName);
            $definedColumns = $articleTypeObject->getUserDefinedColumns(null, $p_showAll, $p_skipCache);
            $cacheService->save($cacheKey, $definedColumns);
        }
        return $definedColumns;
    }

 public function serializeToJson(JsonSerializationVisitor $visitor, $data, $type)
 {
     $articleData = new \ArticleData($data->type, $data->number, $data->languageId);
     if (count($articleData->getUserDefinedColumns()) == 0) {
         return null;
     }
     $fields = array();
     foreach ($articleData->getUserDefinedColumns() as $column) {
         $fields[$column->getPrintName()] = $articleData->getFieldValue($column->getPrintName());
     }
     $fields['show_on_front_page'] = $data->onFrontPage == "Y" ? 1 : 0;
     $fields['show_on_section_page'] = $data->onSection == "Y" ? 1 : 0;
     return $fields;
 }