protected function _formatDate($field, &$attributes)
    {
        if ($this->timestamps && $field) {

            switch ($this->dateFormat) {
                case 'datetime':
                    $dateFormat = date("Y-m-d H:i:s");
                    break;
                
                case 'unixtime':
                default:
                    $dateFormat = time();
                    break;
            }
            
            $attributes[$field] = $dateFormat;
        }

        return $attributes;
    }