public function format_date($field)
    {
        if (!$this->current_row[$field]) {
            $this->current_row[$field] = '-';
        } else {
            if (is_object($this->current_row[$field])) {
                $this->current_row[$field] = $this->current_row[$field]->format(
                    $this->app->getConfig('locale/date', 'd/m/Y')
                );

            } else {
                $this->current_row[$field] = date(
                    $this->app->getConfig('locale/date', 'd/m/Y'),
                    strtotime($this->current_row[$field])
                );
            }
        }
    }