Php 如何在symfony 4中创建自定义表单类型？

我试图通过自己的模板视图创建一个自定义表单类型，但通过搜索并尝试创建一个，我遇到了很多错误

这是我的自定义表单类型文件

ImageChoiceType.php

：

<?php

namespace App\Form\Type;

use App\Entity\Media;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Bridge\Doctrine\Form\Type\EntityType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\OptionsResolver\OptionsResolver;

class ImageChoiceType extends AbstractType
{

    private $entityManager;

    public function __construct(EntityManagerInterface $entityManager)
    {
        $this->entityManager = $entityManager;
    }


    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(
//            'data_class' => Media::class,
            'class' => Media::class,
            'choices' => $this->entityManager->getRepository(Media::class)
                            ->findAll(),
        ));
    }

    public function getParent()
    {
       return EntityType::class;
    }

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'image_choice';
    }

    /**
     * {@inheritdoc}
     */
    public function getBlockPrefix()
    {
        return 'image_choice';
    }
}

<?php

namespace App\Form\Type;

use Symfony\Bridge\Doctrine\Form\Type\EntityType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\OptionsResolver\OptionsResolver;

class ImageChoiceType extends AbstractType
{
    public function configureOptions(OptionsResolver $resolver)
    {
    }

    public function getParent()
    {
        return EntityType::class;
    }

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'image_choice';
    }

    /**
     * {@inheritdoc}
     */
    public function getBlockPrefix()
    {
        return 'image_choice';
    }
}

---

好的，我找到了创建它的方法

那太容易了。文档显示它非常复杂，但事实并非如此

这是自定义表单类型文件
ImageChoiceType.php：

<?php

namespace App\Form\Type;

use App\Entity\Media;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Bridge\Doctrine\Form\Type\EntityType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\OptionsResolver\OptionsResolver;

class ImageChoiceType extends AbstractType
{

    private $entityManager;

    public function __construct(EntityManagerInterface $entityManager)
    {
        $this->entityManager = $entityManager;
    }


    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(
//            'data_class' => Media::class,
            'class' => Media::class,
            'choices' => $this->entityManager->getRepository(Media::class)
                            ->findAll(),
        ));
    }

    public function getParent()
    {
       return EntityType::class;
    }

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'image_choice';
    }

    /**
     * {@inheritdoc}
     */
    public function getBlockPrefix()
    {
        return 'image_choice';
    }
}

<?php

namespace App\Form\Type;

use Symfony\Bridge\Doctrine\Form\Type\EntityType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\OptionsResolver\OptionsResolver;

class ImageChoiceType extends AbstractType
{
    public function configureOptions(OptionsResolver $resolver)
    {
    }

    public function getParent()
    {
        return EntityType::class;
    }

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'image_choice';
    }

    /**
     * {@inheritdoc}
     */
    public function getBlockPrefix()
    {
        return 'image_choice';
    }
}

我在问题中提供的模板正是生成图片的模板