Symfony2 Data Transformer on hidden field

Question

I\'ve searched and not found anyone with this problem.

I\'ve created my own Data Transformer as set out in the Cookbook and it all seems right but i get the error:

Answer 1

This is the way I handle entities with hidden inputs:

DataTransformer

<?php

namespace Comakai\CQZBundle\Form\DataTransformer;

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

class EntityToIdTransformer implements DataTransformerInterface
{
    /**
     * @var ObjectManager
     */
    private $om;
    private $entityClass;

    /**
     * @param ObjectManager $om
     */
    public function __construct(ObjectManager $om, $entityClass)
    {
        $this->om = $om;
        $this->entityClass = $entityClass;
    }

    /**
     * Transforms an object to a string (id).
     *
     * @param  Object|null $entity
     * @return string
     */
    public function transform($entity)
    {
        if (null === $entity) {
            return "";
        }

        return $entity->getId();
    }

    /**
     * Transforms a string (id) to an object.
     *
     * @param  string $id
     * @return Object|null
     * @throws TransformationFailedException if object is not found.
     */
    public function reverseTransform($id)
    {
        if (!$id) {
            return null;
        }

        $entity = $this->om->getRepository($this->entityClass)->findOneById($id);

        if (null === $entity) {

            throw new TransformationFailedException(sprintf(
                    'An entity of class ' . $this->entityClass . ' with id "%s" does not exist!', $id
            ));
        }

        return $entity;
    }

}

FormType

<?php

namespace Comakai\CQZBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Doctrine\Common\Persistence\ManagerRegistry;
use Doctrine\Common\Persistence\ObjectManager;
use Comakai\CQZBundle\Form\DataTransformer\EntityToIdTransformer;

class EntityHiddenType extends AbstractType
{
    /**
     * @var ManagerRegistry
     */
    private $registry;

    /**
     * @var ObjectManager
     */
    private $om;
    private $cache;

    /**
     * @param ObjectManager $om
     */
    public function __construct(ManagerRegistry $registry)
    {
        $this->registry = $registry;
        $this->om = $registry->getManager();
        $this->cache = [];
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $class = (empty($options['data_class'])) ? $this->getClassFromMetadata($builder->getName(), $builder->getParent()->getDataClass()) : $options['data_class'];

        $transformer = new EntityToIdTransformer($this->om, $class);
        $builder->addViewTransformer($transformer);

        $builder->setAttribute('data_class', $class);
    }

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

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

    protected function getClassFromMetadata($name, $parentClass)
    {
        /* @var $md \Doctrine\ORM\Mapping\ClassMetadata */
        $md = $this->getMetadata($parentClass)[0];
        $a = $md->getAssociationMapping($name);
        $class = $a['targetEntity'];

        return $class;
    }

    protected function getMetadata($class)
    {
        if (array_key_exists($class, $this->cache)) {
            return $this->cache[$class];
        }

        $this->cache[$class] = null;
        foreach ($this->registry->getManagers() as $name => $em) {
            try {
                return $this->cache[$class] = array($em->getClassMetadata($class), $name);
            } catch (MappingException $e) {
                // not an entity or mapped super class
            } catch (LegacyMappingException $e) {
                // not an entity or mapped super class, using Doctrine ORM 2.2
            }
        }
    }

}

Config (services.yml)

services:
    cqz.form.type.entity_hidden:
        class: Comakai\CQZBundle\Form\Type\EntityHiddenType
        arguments: ["@doctrine"]
        tags:
                -  { name: form.type, alias: entity_hidden }

JobType

$builder->add('company', 'entity_hidden');

Then in your controller

$job = new \Niche\JobBundle\Entity\Job();
$type = new \Niche\JobBundle\Form\JobType();

$job->setCompany($businessUser);

$form = $this->createForm($type, $job);

This way you'll have a reusable entity_hidden type.

UPDATE FOR 2.3

Since there is no $builder->getParent() anymore (https://github.com/symfony/symfony/blob/master/UPGRADE-2.2.md) and because I don't want to set the class of the field's data, I came up with this (btw, now I'm using the form.type_guesser.doctrine service to get the class):

Config

cqz.form.type.suggest:
        class: Comakai\CQZBundle\Form\Type\SuggestType
        arguments: ["@doctrine.orm.entity_manager", "@form.type_guesser.doctrine"]

DataTransformer

<?php

namespace Comakai\CQZBundle\Form\DataTransformer;

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

class ObjectToIdTransformer implements DataTransformerInterface
{
     /**
     * @var ObjectManager
     */
    private $om;
    private $objectClass;

    /**
     * @param ObjectManager $om
     */
    public function __construct(ObjectManager $om, $objectClass = null)
    {
        $this->om = $om;
        $this->objectClass = $objectClass;
    }

    /**
     * Transforms an object to an id.
     *
     * @param  Object|null $object
     * @return mixed
     */
    public function transform($object)
    {
        if (null === $object) {

            return '';
        }

        return $object->getId();
    }

    /**
     * Transforms an id to an object.
     *
     * @param  mixed $id
     *
     * @return Object|null
     *
     * @throws TransformationFailedException if object is not found.
     */
    public function reverseTransform($id)
    {
        if (!$id) {

            return null;
        }

        $object = $this->om
            ->getRepository($this->objectClass)
            ->find($id)
        ;

        if (null === $object) {

            throw new TransformationFailedException(sprintf(
                'An instance of "%s" with id "%s" does not exist!',
                $this->objectClass,
                $id
            ));
        }

        return $object;
    }

    public function getObjectClass()
    {
        return $this->objectClass;
    }

    public function setObjectClass($class)
    {
        $this->objectClass = $class;
    }
}

Type

<?php

namespace Comakai\CQZBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Doctrine\Common\Persistence\ObjectManager;
use Symfony\Bridge\Doctrine\Form\DoctrineOrmTypeGuesser;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
use Comakai\CQZBundle\Form\DataTransformer\ObjectToIdTransformer;

use Symfony\Component\Form\FormView;
use Symfony\Component\Form\FormInterface;

use Symfony\Component\Form\FormEvents;
use Symfony\Component\Form\FormEvent;

class SuggestType extends AbstractType
{
    /**
     * @var ObjectManager
     */
    private $om;
    private $guesser;

    /**
     * @param ObjectManager $om
     */
    public function __construct(ObjectManager $om, DoctrineOrmTypeGuesser $guesser)
    {
        $this->om = $om;
        $this->guesser = $guesser;
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $transformer = new ObjectToIdTransformer($this->om);
        $builder->addModelTransformer($transformer);

        if($options['class'] === null) {

            $builder->addEventListener(FormEvents::PRE_SET_DATA, function(FormEvent $event) use ($transformer, $builder) {

                /* @var $form \Symfony\Component\Form\Form */
                $form = $event->getForm();
                $class = $form->getParent()->getConfig()->getDataClass();
                $property = $form->getName();
                $guessedType = $this->guesser->guessType($class, $property);
                $options = $guessedType->getOptions();

                $transformer->setObjectClass($options['class']);

            });

        } else {

            $transformer->setObjectClass($options['class']);

        }
    }
    ...

I feel that using a PRE_SET_DATA to set the data class on the transformer is nasty, what do you think?

Answer 2

I just created an input type hidden:

$builder->add('child_id', 'hidden', array('mapped' => false))

In the newAction I did fill with the parent id:

$childForm->get('parent_id')->setData($parentEntity->getId());

And finally in createAction I did put:

$child->setParent($em->getReference('MyBundle:Parent', $form["child_id"]->getData()))

PS: I understand that you wanted to create your Data Transformer, but if your problem is persist object with parent id, it will help you.