Stop SonataAdmin / Symfony2 from creating empty objects with sonata_type_admin embedded admins

Question

First of all, I'm not sure if this is a Sonata issue or a Symfony2 one, this is the first time I'm working with Sf2 forms to edit a relationship.

Here's the problem:

I have two classes, let's call them the old favourites: Car and Wheel. Car has an optional one-to-one relationship with Wheel (it's for the example, just go with it...). I have set up SonataAdmin with a CarAdmin class which embeds a WheelAdmin using sonata_type_admin and try to create a Car without entering any data for Wheel.

However, on submit (somewhere in $form->bind()/$form->submit() as far as I can trace) Symfony and/or Sonata is instantiating a Wheel and trying to persist it (with all its values as null). Since the Wheel has some non-null constraints this throws a DBALException complaining that you cannot INSERT a Wheel with null vlaues.

This is naughty and I'd like to stop it happening. If I don't enter any details for Wheel I don't want a phantom Wheel menacing my code and database. What I expect is that if I enter no data there is nothing to insert/persist so it's left alone. But this is not what's happening... any ideas how to tame this into something sensible?

---

Here's the long version, with code blocks and everything:

The ORM definitions first:

# MyNS\MyBundle\Resources\Config\Doctrine\Car.orm.yml
MyNS\MyBundle\Entity\Car:
  type: entity
  repositoryClass: MyNS\MyBundle\Entity\Repositories\CarRepository
  table: test_cars
  id:
    id:
      type:                     integer
      generator:                { strategy: AUTO }
  fields:
    color:
      type:                     string
      length:                   50
    owner:
      type:                     string
      length:                   50
      nullable:                 true
  oneToOne:
    leftFrontWheel:
      targetEntity:             Wheel
      cascade:                  [ persist ]
      joinColumn:
        name:                   leftFrontWheelId
        referencedColumnName:   id


# MyNS\MyBundle\Resources\Config\Doctrine\Wheel.orm.yml
MyNS\MyBundle\Entity\Wheel:
  type: entity
  repositoryClass: MyNS\MyBundle\Entity\Repositories\WheelRepository
  table: test_wheels
  id:
    id:
      type:                     integer
      generator:                { strategy: AUTO }
  fields:
    diameter:
      type:                     integer
      length:                   5

Then the SonataAdmin classes:

namespace MyNS\MyBundle\Admin

use ...

class CarAdmin extends Admin
{
    protected function configureFormFields(FormMapper $formMapper)
    {
        $formMapper
            ->add('color',              null, array('required' => true))
            ->add('owner',              null, array('required' => false))
            ->add('leftFrontWheel',     'sonata_type_admin', array('delete' => false))
        ;
    }

    protected function configureListFields(ListMapper $listMapper) { ... }
}

and

namespace MyNS\MyBundle\Admin;

use ...

class WheelAdmin extends Admin
{
    protected function configureFormFields(FormMapper $formMapper)
    {
        $formMapper
            ->add('diameter',   null,   array('required' => false))
        ;
    }

    protected function configureListFields(ListMapper $listMapper) { ... }
}

and finally the admin.yml entries:

services:
    sonata.admin.car:
        class: MyNS\MyBundle\Admin\CarAdmin
        tags:
            - { name: sonata.admin, manager_type: orm, label: "Car" }
        arguments:
            - ~
            - MyNS\MyBundle\Entity\Car
            - 'SonataAdminBundle:CRUD'
        calls:
            - [ setTranslationDomain, [MyNS\MyBundle]]
    sonata.admin.wheel:
        class: MyNS\MyBundle\Admin\WheelAdmin
        tags:
            - { name: sonata.admin, manager_type: orm, label: "Wheel" }
        arguments:
            - ~
            - MyNS\MyBundle\Entity\Wheel
            - 'SonataAdminBundle:CRUD'
        calls:
            - [ setTranslationDomain, [MyNS\MyBundle]]

Expected/required behaviour:

• Display a form with three fields:

  • car.color (required)
  • car.owner (optional)
  • car.wheel.diameter (optional)

• if car.wheel.diameter is left blank then no Wheel should be created and test_cars.leftFrontWheelId should remain null in the database

• if car.wheel.diameter is entered then a Wheel should be created and linked to the Car (this seems to work fine with the existing config)

The question: How do I get this system to behave as above?

Answer 1

It might be caused by a missing 'required' => false, no ?

protected function configureFormFields(FormMapper $formMapper) {
    $formMapper
        ->add('color',              null, array('required' => true))
        ->add('owner',              null, array('required' => false))
        ->add('leftFrontWheel',     'sonata_type_admin', array('required' => false, 'delete' => false))
    ;
}

Answer 2

Change your Wheel form field for something like :

$formMapper
    // ...
    ->add('leftFrontWheel', 'sonata_type_admin', array(
        'delete' => false,
        'by_reference => true,
        'required' => false,
    ))
    // ...

See by_reference documentation

If it's not sufficient, use a prePersist hook in your parent admin class and manage which field you store. i.e. :

// Fire on submit, before the object persisting
public function prePersist($object)
    if ($wheel = $object->getLeftFrontWheel()) {
        if (!$wheel->getYourNonNullableField()) {
            $object->setLefTFrontWheel(null);
        }
    }
}