如何使用APYDataGridBundle在网格中显示关系列？

use APY\DataGridBundle\Grid\Column\RelationColumn;
use APY\DataGridBundle\Grid\Grid;

class UserGrid extends Grid
{
    protected function buildGrid()
    {
        $this->addColumn(new RelationColumn([
            'id'       => 'orderCount',
            'field'    => 'orders',
            'relation' => 'AppBundle\Entity\Order',
            'title'    => 'Order Count',
            'select'   => 'COUNT(orders.id)',
        ]));
    }
}

use AppBundle\Grid\UserGrid;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Response;

class UserController extends AbstractController
{
    public function indexAction()
    {
        $grid = $this->container->get('grid')->createGrid(UserGrid::class);
        $grid->getColumn('orderCount')->setFilters([]); // 可选：设置筛选选项

        return $this->render('user/index.html.twig', [
            'grid' => $grid
        ]);
    }
}

{{ grid(grid) }}