public function getTotalsRowHTML()
    {
        $output = [];
        foreach ($this->columns as $name => $column) {
            // if no totals plan, then show dash, but keep column formatting
            if (!isset($this->totals_plan[$name])) {
                $output[] = $column->getTag('foot', '-');
                continue;
            }

            // if totals plan is set as array, then show formatted value
            if (is_array($this->totals_plan[$name])) {
                // todo - format
                $field = $this->model->getElement($name);
                $output[] = $column->getTotalsCellHTML($field, $this->totals[$name]);
                continue;
            }

            // otherwise just show it, for example, "Totals:" cell
            $output[] = $column->getTag('foot', $this->totals_plan[$name]);
        }

        return implode('', $output);
    }