public function renderFilters()
    {
        if (isset($_GET['filter'])) {
            if (isset($_GET['q'])) {
                $this->model->addCondition($_GET['filter'], 'like', '%'.$_GET['q'].'%');
            }
            // Apply filtering to filter.
            $this->applyFilters();
            $action = $this->model->action('field', [$_GET['filter']]);
            $action->group($_GET['filter']);
            $rows = $action->get();
            $data = [];
            foreach ($rows as $k => $v) {
                $data[] = ['id' => $k, 'name' => $v[$_GET['filter']]];
            }
            array_unshift($data, ['id' => -1, 'name' => $this->filterEmpty]);

            $this->app->terminate(json_encode([
                                                  'success' => true,
                                                  'results' => $data,
                                              ]));
        }
    }