模型转换器和预期的表单视图数据不匹配

Question

我有一个 Symfony 2 应用程序，其表单需要在隐藏字段中存储对另一个实体（项目）的引用。项目实体是通过表单选项传入的，我的计划是有一个 'hidden' 类型的字段，它只包含实体 ID，然后应该在提交表单时将其转换为项目实体。

我将通过使用模型转换器在实体与字符串（它的 ID）之间进行转换来解决这个问题。但是，当我尝试查看表单时，出现以下错误：

The form's view data is expected to be an instance of class Foo\BarBundle\Entity\Project, but is a(n) string. You can avoid this error by setting the "data_class" option to null or by adding a view transformer that transforms a(n) string to an instance of Foo\BarBundle\Entity\Project.

这是我的表格class:

<?php

namespace Foo\BarBundle\Form\SED\Waste;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
use Foo\BarBundle\Form\DataTransformer\EntityToEntityIdTransformer;

/**
 * Class WasteContractorEntryType
 * @package Foo\BarBundle\Form\CommunityInvestment\Base
 */
class WasteContractorEntryType extends AbstractType
{

    protected $name;

    protected $type;

    protected $phase;

    protected $wasteComponent;

    public function __construct($formName, $type, $phase, $wasteComponent)
    {
        $this->name = $formName;
        $this->type = $type;
        $this->phase = $phase;
        $this->wasteComponent = $wasteComponent;
    }

    /**
     * @return mixed
     */
    public function getType()
    {
        return $this->type;
    }

    /**
     * @return mixed
     */
    public function getPhase()
    {
        return $this->phase;
    }

    /**
     * @return mixed
     */
    public function getProject()
    {
        return $this->project;
    }

    /**
     * @return mixed
     */
    public function getWasteComponent()
    {
        return $this->wasteComponent;
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $em = $options['em'];

        $wasteComponentTransformer = new EntityToEntityIdTransformer($em,
            'Foo\BarBundle\Entity\SED\Waste\WasteComponent');

        $projectTransformer = new EntityToEntityIdTransformer($em, 'Foo\BarBundle\Entity\Project');

        $builder->add('id', 'hidden');

        $builder->add(
            $builder->create('project', 'hidden', array(
                'data' => $options['project'],
                'by_reference' => false
            ))
                ->addModelTransformer($projectTransformer)
        );

        $builder->add(
            $builder->create('wasteComponent', 'hidden', array(
                'data' => $this->getWasteComponent()
            ))
                ->addModelTransformer($wasteComponentTransformer)
        );

        $builder->add('phase', 'hidden', array(
            'data' => $this->getPhase()
        ));

        $builder->add('type', 'hidden', array(
            'data' => $this->getType()
        ));

        $builder->add('percentDivertedFromLandfill', 'text', array());

        $builder->add('wasteContractor', 'entity', array(
            'class' => 'Foo\BazBundle\Entity\Contractor',
            'property' => 'name',
            'attr' => array(
                'class' => 'js-select2'
            )
        ));
    }


    public function getName()
    {
        return $this->name;
    }

    /**
     * {@inheritDoc}
     */
    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'csrf_protection' => true,
            'data_class' => 'Foo\BarBundle\Entity\SED\Waste\WasteContractorEntry'
        ))
            ->setRequired(array(
                'em',
                'project'
            ))
            ->setAllowedTypes(array(
                'em' => 'Doctrine\Common\Persistence\ObjectManager',
                'project' => 'Foo\BarBundle\Entity\Project'
            ));

    }

}

还有我的模型变压器class:

<?php

namespace Foo\BarBundle\Form\DataTransformer;

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

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

    /**
     * @var Entity class
     */
    protected $entityClass;

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

    protected function getEntityClass()
    {
        return $this->entityClass;
    }

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

        return $entity->getId();
    }

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

        $entity = $this->om
            ->getRepository($this->getEntityClass())
            ->find($id);

        if (null === $entity) {
            throw new TransformationFailedException(sprintf(
                'An entity of class %s with id "%s" does not exist!',
                $this->getEntityClass(),
                $id
            ));
        }

        return $entity;
    }
}

我尝试使用添加转换器作为视图转换器而不是模型转换器，但是我只是得到一个稍微不同的错误：

The form's view data is expected to be an instance of class Foo\BarBundle\Entity\Project, but is a(n) integer. You can avoid this error by setting the "data_class" option to null or by adding a view transformer that transforms a(n) integer to an instance of Foo\BarBundle\Entity\Project.

Answer 1

似乎按照上面异常消息的建议将 'data_class' 设置为 null 是解决方案。我之前拒绝了这一点，因为当我们知道该字段的目的是引用项目实体时，这似乎违反直觉。

将 'data_class' 选项设置为 null，隐藏的项目字段包含项目 ID，提交后，在创建的实体上调用 getProject() returns 正确的项目对象。

模型转换器和预期的表单视图数据不匹配

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