Hidden field for Symfony2 entities

EntityHiddenType.php

<?php

namespace Dpn\ToolsBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Dpn\ToolsBundle\Form\DataTransformer\EntityToIdTransformer;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
use Doctrine\Common\Persistence\ObjectManager;

class EntityHiddenType extends AbstractType
{
    /**
     * @var ObjectManager
     */
    protected $objectManager;

    public function __construct(ObjectManager $objectManager)
    {
        $this->objectManager = $objectManager;
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $transformer = new EntityToIdTransformer($this->objectManager, $options['class']);
        $builder->addModelTransformer($transformer);
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver
            ->setRequired(array('class'))
            ->setDefaults(array(
                'invalid_message' => 'The entity does not exist.',
            ))
        ;
    }

    public function getParent()
    {
        return 'hidden';
    }

    public function getName()
    {
        return 'entity_hidden';
    }
}

EntityToIdTransformer.php

<?php

namespace Dpn\ToolsBundle\Form\DataTransformer;

use Symfony\Component\Form\DataTransformerInterface;
use Symfony\Component\Form\Exception\TransformationFailedException;
use Doctrine\Common\Persistence\ObjectManager;

class EntityToIdTransformer implements DataTransformerInterface
{
    /**
     * @var ObjectManager
     */
    protected $objectManager;

    /**
     * @var string
     */
    protected $class;

    public function __construct(ObjectManager $objectManager, $class)
    {
        $this->objectManager = $objectManager;
        $this->class = $class;
    }

    public function transform($entity)
    {
        if (null === $entity) {
            return;
        }

        return $entity->getId();
    }

    public function reverseTransform($id)
    {
        if (!$id) {
            return null;
        }

        $entity = $this->objectManager
                       ->getRepository($this->class)
                       ->find($id);

        if (null === $entity) {
            throw new TransformationFailedException();
        }

        return $entity;
    }
}

Thanks!!! Great Job!!!

If the user doesn't write the class option:

$builder
        ->add('car', 'hidden_entity', array())
;

the class is null and the transformation throws the next error:
Class '' does not exist

If the user uses the method setRequired() in EntityHiddenType file:

public function setDefaultOptions(OptionsResolverInterface $resolver)
{
    $resolver
        ->setRequired(array('class'))
        ->setDefaults(array(
            'invalid_message' => 'The entity does not exist.',
        ))
    ;
}

the application throws a 500 error with the next information:
The required option "class" is missing.

Hi @jamogon,

thanks for the hint. I updated the Gist accordingly. Didn't even know about the setRequired() method of the OptionsResolver.

Cheers
Björn

Great Job !!

Thank you !

Why Symfony community would not integrate this solution. it's very useful !

👍

Did you ever propose this improvement to Symfony, @bjo3rnf ?

There also seems to be a simple workaround using the property_path:

$builder->add('entity', 'hidden', array('property_path' => 'entity.id'));

as mentioned by @webmozart here:
symfony/symfony#3182

And it looks like it is finally going to make it into symfony here:
symfony/symfony#8293

Thank you! Works great!

How to pass default value to Hidden_entity field? for eg. I have test controller which has field Author. Author I am getting from db after user logs in to system.

How can I set an entity in a onPreSubmit or preSetData and have it attach to the form entity?

Thanks! It helped a lot!

I forked it to make it compatible with symfony 2.8 ( https://gist.github.com/xanou/e630e4e25df60d33b050 )

Thanks, you made my day!