public function renderLengthPicker()
    {
        $pagination = $this->dataProvider->getPagination();
        if ($pagination === false || $this->dataProvider->getCount() <= 0) {
            return '';
        }
        $pagination->totalCount = $this->dataProvider->getTotalCount();
        $choices = [];
        foreach ([10, 25, 50] as $value) {
            $cssClass = $value === $pagination->pageSize ? 'active' : '';
            $url = $pagination->createUrl($pagination->getPage(), $value);
            $choices[] = '<li class="'.$cssClass.'"><a href="' . $url . '">' . $value . '</a></li>';
        }
        return Html::tag('ul', implode("\n", $choices), $this->lengthPickerOptions);
    }