Entity choicelist without bringing the whole entity

Symfony forms have a nice entity type, but it will eat your memory if you have too large entity. Only answer I found while trying to find a fix for that was this nice StackOverflow answer, but nothing else.

The deal is to not bring the whole entity but only the needed information, like id and name to feed an HTML select tag. More details in the Gist:

	<?php

	namespace CommonBundle\Form;

	use CommonBundle\Form\Transformer\EntityToIdTransformer;
	use Doctrine\Bundle\DoctrineBundle\Registry;
	use Doctrine\Common\Persistence\ManagerRegistry;
	use Doctrine\Common\Persistence\ObjectManager;
	use Symfony\Component\Form\AbstractType;
	use Symfony\Component\Form\FormBuilderInterface;
	use Symfony\Component\OptionsResolver\Options;
	use Symfony\Component\OptionsResolver\OptionsResolver;

	class EntityChoiceType extends AbstractType
	{
	/**
	* @var Registry
	*/
	private $registry;

	public function __construct(Registry $registry)
	{
	$this->registry = $registry;
	}

	public function buildForm(FormBuilderInterface $builder, array $options)
	{
	$builder->addModelTransformer(
	new EntityToIdTransformer($options['em']->getRepository($options['class']))
	);
	}

	public function configureOptions(OptionsResolver $resolver)
	{
	$registry = $this->registry;

	$resolver->setDefaults(array(
	'empty_value' => false,
	'empty_data' => null,
	'em' => null,
	'query_builder' => null,
	'field' => 'id',
	));

	$resolver->setRequired(array(
	'class'
	));

	$resolver->setDefault('choices', function (Options $options) use ($registry) {
	if (null === $options['query_builder']) {
	$results = $options['em']
	->createQueryBuilder()
	->select('e.id', 'e.'.$options['field'])
	->from($options['class'], 'e', 'e.id')
	->orderBy('e.'.$options['field'], 'ASC')
	->getQuery()
	->getArrayResult()
	;
	} else {
	$results = $options['query_builder']
	->getQuery()
	->getArrayResult()
	;
	}

	return array_map(
	function($value) {
	return end($value);
	}, $results
	);
	});

	$queryBuilderNormalizer = function (Options $options, $queryBuilder) {
	if (is_callable($queryBuilder)) {
	$queryBuilder = call_user_func($queryBuilder, $options['em']->getRepository($options['class']));
	}

	return $queryBuilder;
	};

	$emNormalizer = function (Options $options, $em) use ($registry) {
	/* @var ManagerRegistry $registry */
	if (null !== $em) {
	if ($em instanceof ObjectManager) {
	return $em;
	}

	return $registry->getManager($em);
	}

	$em = $registry->getManagerForClass($options['class']);

	if (null === $em) {
	throw new \Exception(sprintf(
	'Class "%s" seems not to be a managed Doctrine entity. '.
	'Did you forget to map it?',
	$options['class']
	));
	}

	return $em;
	};

	$resolver->setNormalizer('em', $emNormalizer);
	$resolver->setNormalizer('query_builder', $queryBuilderNormalizer);
	}

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

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

view raw EntityChoiceType.php hosted with ❤ by GitHub

	<?php

	namespace CommonBundle\Form\Transformer;

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

	class EntityToIdTransformer implements DataTransformerInterface
	{
	private $entityRepository;

	public function __construct(ObjectRepository $entityRepository)
	{
	$this->entityRepository = $entityRepository;
	}

	/**
	* @param object\|array $entity
	* @return int\|int[]
	*
	* @throws TransformationFailedException
	*/
	public function transform($entity)
	{
	if ($entity === null) {
	return null;
	} elseif (is_array($entity) \|\| $entity instanceof \Doctrine\ORM\PersistentCollection) {
	$ids = array();
	foreach ($entity as $subEntity) {
	$ids[] = $subEntity->getId();
	}

	return $ids;
	} elseif (is_object($entity)) {
	return $entity->getId();
	}

	throw new TransformationFailedException((is_object($entity)? get_class($entity) : '').'('.gettype($entity).') is not a valid class for EntityToIdTransformer');
	}

	/**
	* @param int\|array $id
	* @return object\|object[]
	*
	* @throws TransformationFailedException
	*/
	public function reverseTransform($id)
	{
	if ($id === null) {
	return null;
	} elseif (is_numeric($id)) {
	$entity = $this->entityRepository->findOneBy(array('id' => $id));

	if ($entity === null) {
	throw new TransformationFailedException('A '.$this->entityRepository->getClassName().' with id #'.$id.' does not exist!');
	}

	return $entity;
	} elseif (is_array($id)) {

	if (empty($id)) {
	return array();
	}

	$entities = $this->entityRepository->findBy(array('id' => $id)); // its array('id' => array(...)), resulting in many entities!!

	if (count($id) != count($entities)) {
	throw new TransformationFailedException('Some '.$this->entityRepository->getClassName().' with ids #'.implode(', ', $id).' do not exist!');
	}

	return $entities;
	}

	throw new TransformationFailedException(gettype($id).' is not a valid type for EntityToIdTransformer');
	}
	}

view raw EntityToIdTransformer.php hosted with ❤ by GitHub

	<?php

	namespace MyBundle\Form;

	use Symfony\Component\Form\AbstractType;
	use Symfony\Component\Form\FormBuilderInterface;
	use Symfony\Component\Form\FormEvent;
	use Symfony\Component\Form\FormEvents;
	use Symfony\Component\Form\FormInterface;
	use Symfony\Component\OptionsResolver\OptionsResolver;

	class MyFormType extends AbstractType
	{
	public function buildForm(FormBuilderInterface $builder, array $options)
	{
	$builder
	->add('thing', 'entity_choice', array(
	'class' => 'MyBundle:MyEntity',
	'field' => 'my_entity_name',
	))
	->addEventListener(FormEvents::PRE_SET_DATA, function (FormEvent $event) use ($options) {
	/** @var Request $request */
	$request = $event->getData();
	$thing = (null !== $request && null !== $request->getThing()) ? $request->getThing() : null;

	$this->addThingFields($event->getForm(), $options, $thing);
	})
	;

	$builder->get('thing')->addEventListener(FormEvents::POST_SUBMIT, function (FormEvent $event) use ($options) {
	$this->addThingFields($event->getForm()->getParent(), $options, $event->getForm()->getData());
	})
	;
	}
	}

view raw MyFormType.php hosted with ❤ by GitHub

	services:
	common.form.entity_choice:
	class: CommonBundle\Form\EntityChoiceType
	arguments:
	- @doctrine
	tags:
	- { name: form.type, alias: entity_choice }

view raw services.yml hosted with ❤ by GitHub

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Entity choicelist without bringing the whole entity