我以一对一的关系加入了两个表（政策和车辆）。 我想从vehicle.policy为null的车辆获取记录

Question

I am creating a Form form Policy where i want show those vehicles are not already used or associated with policy since its a one to one relation ship, and i am using query_builder for this purpose but i am not getting filtered results.

$form = $this->createFormBuilder($policy)
    ->add('vehicle', EntityType::class,[
          'class'=>Vehicle::class,
          'label' => 'Vehicle Plate',
          'query_builder' => function (VehicleRepository $vr){
          return $vr->createQueryBuilder('vehicle')
                 ->andWhere('vehicle.policy IS NULL');
           }])

But i am getting this error

A single-valued association path expression to an inverse side is not supported in DQL queries. Instead of "vehicle.policy" use an explicit join.

Answer 1

Try this :

$form = $this->createFormBuilder($policy)
->add('vehicle', EntityType::class,[
      'class'=>Vehicle::class,
      'label' => 'Vehicle Plate',
      'query_builder' => function (VehicleRepository $vr){
             return $vr->createQueryBuilder('v')
             ->leftJoin('v.policy', 'policy')
            ->where('policy is NULL');
       }])