问题描述：

当使用Api Platform框架进行ORM映射时，如果实体类中存在OneToMany关系，Api Platform将无法持久化数据。这是因为生成的实体仅包含主表的声明，而子表的声明被忽略了。

为了解决这个问题，我们需要手动创建并保存子表的记录。这可以通过在主实体中触发事件来实现。我们需要创建一个侦听器（listener），它会监听主实体的预持久化事件，并在保存主实体之前创建并保存子实体。

以下是一个示例，我们将在User实体中创建一个Profile实体：

// User.php
use Doctrine\ORM\Mapping as ORM;
use ApiPlatform\Core\Annotation\ApiProperty;

/**
 * @ApiResource()
 * @ORM\EntityListeners({"App\EntityListener\CreateProfileListener"})
 */
class User
{
    /**
     * @ORM\OneToMany(targetEntity="App\Entity\Profile", mappedBy="user", cascade={"persist"})
     */
    private $profile;

    public function __construct()
    {
        $this->profile = new ArrayCollection();
    }

    public function addProfile(Profile $profile): self
    {
        if (!$this->profile->contains($profile)) {
            $this->profile[] = $profile;
            $profile->setUser($this);
        }

        return $this;
    }

    public function removeProfile(Profile $profile): self
    {
        if ($this->profile->contains($profile)) {
            $this->profile->removeElement($profile);
            if ($profile->getUser() === $this) {
                $profile->setUser(null);
            }
        }

        return $this;
    }
}

// Profile.php
use Doctrine\ORM\Mapping as ORM;
use ApiPlatform\Core\Annotation\ApiProperty;

/**
 * @ORM\Entity
 */
class Profile
{
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\User", inversedBy="profile")
     * @ORM\JoinColumn(nullable=false)
     */
    private $user;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $firstName;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $lastName;

    public function getId(): ?int
    {
        return $this->id;
    }

    public function getUser(): ?User
    {
        return $this->user;
    }

    public function setUser(?User $user): self
    {
        $this->user = $user;

        return $this;
    }

    public function getFirstName(): ?string
    {
        return $this->firstName;
    }

    public function setFirstName(string $firstName): self
    {
        $this->firstName = $firstName;

        return $this;
    }

    public function getLastName(): ?string
    {
        return $this->lastName;
    }

    public function setLastName(string $lastName): self
    {
        $this->lastName = $lastName;

        return $this;
    }
}

// CreateProfileListener.php
namespace App\EntityListener;

use App\Entity\User;
use App\Entity\Profile;
use Doctrine\ORM\Event\LifecycleEventArgs;

class CreateProfileListener
{
    public function prePersist(User $user, LifecycleEventArgs $event): void
    {
        $entityManager = $event->getEntityManager();
        $profile = new Profile();
        $profile->setUser($user);
        $entityManager->