Symfony 4个单一形式的多个实体

努力工作了好几个小时才能使我的多实体表单正常工作，但这确实让我伤脑筋，而我发现的所有示例都没有。

我检查了“集合”表单类型文档和表单集合，以及“实体”表单类型。

我有一个用户实体，一个UserRole实体和一个Role实体。UserRole包含一个用户ID和一个角色ID。只是一个链接表。

该表单显示了用于创建用户的字段，我希望能够为新用户选择一个新角色。因此，我尝试使用EntityType，一个选择下拉列表很好地显示了所有角色（仅当我添加映射选项=> false时才显示），但是在表单提交后不进行处理。它的数据不在$ form-> getData（）中，已创建用户，从未创建过user_role条目。如果我在没有映射的=> false的情况下尝试，则会抛出以下错误：

Could not determine access type for property "user_roles" in class "App\Entity\User": The property "user_roles" in class "App\Entity\User" can be defined with the methods "addUserRole()", "removeUserRole()" but the new value must be an array or an instance of \Traversable, "App\Entity\Role" given..

码：

$form = $this->createFormBuilder(new User)
    ... //other add entries
    ->add('user_roles', EntityType::class, array(
        'label' => 'Group (role)',
        'class' => Role::class,
        'choice_label' => 'name',
        // 'mapped' => false, // Form works when false, but doesn't save/create UserRole entry
    ))
->getForm();

$form->handleRequest($request);

使用CollectionType根本不显示选择下拉列表。码：

$form = $this->createFormBuilder($user)
    .... //other add entries
    ->add('user_roles', CollectionType::class, array(
        'entry_type' => ChoiceType::class,
        'entry_options' => array(
            'choices' => $roleChoices,
        ),
    ))
->getForm();

$form->handleRequest($request);

我是否在控制器代码中丢失了某些内容，或者我误解了Form类型的使用？我真的不知道我在做什么错。

用户实体：

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Security\Core\User\UserInterface;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use JMS\Serializer\Annotation\Exclude;

/**
 * @ORM\Entity(repositoryClass="App\Repository\UserRepository")
 * @ORM\HasLifecycleCallbacks()
 */
class User implements UserInterface
{
    /**
     * @ORM\Column(type="string", length=255, nullable=true)
     * @Exclude
     */
    private $apiToken;

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

    /**
     * @ORM\Column(type="string", length=180, unique=true)
     */
    private $email;

    /**
     * @ORM\Column(type="json_array")
     */
    private $roles = [];

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

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

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

    /**
     * @ORM\Column(type="boolean")
     */
    private $enabled;

    /**
     * @ORM\Column(type="datetime", nullable=true)
     */
    private $blocked_at;

    /**
     * @ORM\OneToMany(targetEntity="App\Entity\Project", mappedBy="created_by")
     */
    private $projects;

    /**
     * @ORM\OneToMany(targetEntity="App\Entity\UserRole", mappedBy="user", fetch="EAGER")
     */
    private $user_roles;

    /**
     * @ORM\OneToMany(targetEntity="App\Entity\Category", mappedBy="created_by")
     */
    private $categories;

    /**
     * @ORM\OneToMany(targetEntity="App\Entity\ProjectFileIos", mappedBy="created_by")
     */
    private $projectFileIos;

    /**
     * @ORM\OneToMany(targetEntity="App\Entity\ProjectFileAndroid", mappedBy="created_by")
     */
    private $projectFileAndroid;

    /**
     * Generate full name
     */
    private $full_name;

    /**
     * @var string The hashed password
     * @ORM\Column(type="string")
     * @Exclude
     */
    private $password;

    /**
     * @ORM\OneToMany(targetEntity="App\Entity\ProjectUser", mappedBy="user", fetch="EAGER")
     */
    private $projectUsers;

    /**
     * @ORM\Column(type="datetime")
     */
    private $created_at;

    /**
     * @ORM\Column(type="datetime")
     */
    private $updated_at;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\User", inversedBy="project")
     */
    private $created_by;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\User", inversedBy="project")
     * @ORM\JoinColumn(nullable=true)
     */
    private $last_updated_by;

    public function __construct()
    {
        $this->user_roles = new ArrayCollection();
        $this->user_role = new ArrayCollection();
        $this->categories = new ArrayCollection();
        $this->projectFileIos = new ArrayCollection();
        $this->projectFileAndroid = new ArrayCollection();
        $this->projectUsers = new ArrayCollection();
    }

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

    public function getApiToken(): ?string
    {
        return $this->apiToken;
    }

    public function setApiToken(string $apiToken): self
    {
        $this->apiToken = $apiToken;

        return $this;
    }

    public function getEmail(): ?string
    {
        return $this->email;
    }

    public function setEmail(string $email): self
    {
        $this->email = $email;

        return $this;
    }

    /**
     * A visual identifier that represents this user.
     *
     * @see UserInterface
     */
    public function getUsername(): string
    {
        return (string) $this->email;
    }

    /**
     * @see UserInterface
     */
    public function getRoles(): array
    {
        $roles = $this->roles;
        // guarantee every user at least has ROLE_USER
        $roles[] = 'ROLE_USER';

        return array_unique($roles);
    }

    public function setRoles(array $roles): self
    {
        $this->roles = $roles;

        return $this;
    }

    /**
     * @see UserInterface
     */
    public function getPassword(): string
    {
        return (string) $this->password;
    }

    public function setPassword(string $password): self
    {
        $this->password = $password;

        return $this;
    }

    /**
     * @see UserInterface
     */
    public function getSalt()
    {
        // not needed when using the "bcrypt" algorithm in security.yaml
    }

    /**
     * @see UserInterface
     */
    public function eraseCredentials()
    {
        // If you store any temporary, sensitive data on the user, clear it here
        // $this->plainPassword = null;
    }

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

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

        return $this;
    }

    public function getMiddleName(): ?string
    {
        return $this->middle_name;
    }

    public function setMiddleName(string $middle_name): self
    {
        $this->middle_name = $middle_name;

        return $this;
    }

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

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

        return $this;
    }

    public function getEnabled(): ?bool
    {
        return $this->enabled;
    }

    public function setEnabled(bool $enabled): self
    {
        $this->enabled = $enabled;

        return $this;
    }

    public function getBlockedAt(): ?\DateTimeInterface
    {
        return $this->blocked_at;
    }

    public function setBlockedAt(?\DateTimeInterface $blocked_at): self
    {
        $this->blocked_at = $blocked_at;

        return $this;
    }

    /**
     * @return Collection|UserRole[]
     */
    public function getUserRoles(): ?Collection
    {
        return $this->user_roles;
    }
    public function getUserRole(): ?Collection
    {
        return $this->user_role;
    }

    public function addUserRole(UserRole $userRole): self
    {
        if (!$this->user_role->contains($userRole)) {
            $this->user_role[] = $userRole;
            $user_role->setUserId($this);
        }

        return $this;
    }

    public function removeUserRole(UserRole $userRole): self
    {
        if ($this->user_role->contains($userRole)) {
            $this->user_role->removeElement($userRole);
            // set the owning side to null (unless already changed)
            if ($user_role->getUserId() === $this) {
                $user_role->setUserId(null);
            }
        }

        return $this;
    }

    /**
     * @return Collection|Project[]
     */
    public function getProjects(): Collection
    {
        return $this->projects;
    }

    public function addProject(Project $project): self
    {
        if (!$this->project->contains($project)) {
            $this->project[] = $project;
            $project->setUserId($this);
        }

        return $this;
    }

    public function removeProject(Project $project): self
    {
        if ($this->project->contains($project)) {
            $this->project->removeElement($project);
            // set the owning side to null (unless already changed)
            if ($project->getUserId() === $this) {
                $project->setUserId(null);
            }
        }

        return $this;
    }

    /**
     * @return Collection|Category[]
     */
    public function getCategories(): Collection
    {
        return $this->categories;
    }

    public function addCategory(Category $category): self
    {
        if (!$this->categories->contains($category)) {
            $this->categories[] = $category;
            $category->setCreatedBy($this);
        }

        return $this;
    }

    public function removeCategory(Category $category): self
    {
        if ($this->categories->contains($category)) {
            $this->categories->removeElement($category);
            // set the owning side to null (unless already changed)
            if ($category->getCreatedBy() === $this) {
                $category->setCreatedBy(null);
            }
        }

        return $this;
    }

    /**
     * @return Collection|ProjectFileIos[]
     */
    public function getProjectFileIos(): Collection
    {
        return $this->projectFileIos;
    }

    public function addProjectFileIo(ProjectFileIos $projectFileIo): self
    {
        if (!$this->projectFileIos->contains($projectFileIo)) {
            $this->projectFileIos[] = $projectFileIo;
            $projectFileIo->setCreatedBy($this);
        }

        return $this;
    }

    public function removeProjectFileIo(ProjectFileIos $projectFileIo): self
    {
        if ($this->projectFileIos->contains($projectFileIo)) {
            $this->projectFileIos->removeElement($projectFileIo);
            // set the owning side to null (unless already changed)
            if ($projectFileIo->getCreatedBy() === $this) {
                $projectFileIo->setCreatedBy(null);
            }
        }

        return $this;
    }

    /**
     * @return Collection|ProjectFileAndroid[]
     */
    public function getProjectFileAndroid(): Collection
    {
        return $this->projectFileAndroid;
    }

    public function addProjectFileAndroid(ProjectFileAndroid $projectFileAndroid): self
    {
        if (!$this->projectFileAndroid->contains($projectFileAndroid)) {
            $this->projectFileAndroid[] = $projectFileAndroid;
            $projectFileAndroid->setCreatedBy($this);
        }

        return $this;
    }

    public function removeProjectFileAndroid(ProjectFileAndroid $projectFileAndroid): self
    {
        if ($this->projectFileAndroid->contains($projectFileAndroid)) {
            $this->projectFileAndroid->removeElement($projectFileAndroid);
            // set the owning side to null (unless already changed)
            if ($projectFileAndroid->getCreatedBy() === $this) {
                $projectFileAndroid->setCreatedBy(null);
            }
        }

        return $this;
    }

    public function getFullName()
    {
        $lastName = $this->middle_name ? $this->middle_name . ' ' : '';
        $lastName .= $this->last_name;
        return $this->first_name . ' ' . $lastName;
    }

    /**
     * Triggered after entity has been loaded into the current EntityManager from de database
     * or after refresh operation applied to it
     * @ORM\PostLoad
     */
    public function postLoad()
    {
        $this->full_name = $this->getFullName();
    }

    /**
     * @return Collection|ProjectUser[]
     */
    public function getProjectUsers(): Collection
    {
        return $this->projectUsers;
    }

    public function addProjectUser(ProjectUser $projectUser): self
    {
        if (!$this->projectUsers->contains($projectUser)) {
            $this->projectUsers[] = $projectUser;
            $projectUser->setUser($this);
        }

        return $this;
    }

    public function removeProjectUser(ProjectUser $projectUser): self
    {
        if ($this->projectUsers->contains($projectUser)) {
            $this->projectUsers->removeElement($projectUser);
            // set the owning side to null (unless already changed)
            if ($projectUser->getUser() === $this) {
                $projectUser->setUser(null);
            }
        }

        return $this;
    }

    public function getCreatedAt(): ?\DateTimeInterface
    {
        return $this->created_at;
    }

    public function setCreatedAt(\DateTimeInterface $created_at): self
    {
        $this->created_at = $created_at;

        return $this;
    }

    public function getUpdatedAt(): ?\DateTimeInterface
    {
        return $this->updated_at;
    }

    public function setUpdatedAt(\DateTimeInterface $updated_at): self
    {
        $this->updated_at = $updated_at;

        return $this;
    }

    public function getCreatedBy(): ?User
    {
        return $this->created_by;
    }

    public function setCreatedBy(?User $created_by): self
    {
        $this->created_by = $created_by;

        return $this;
    }

    public function getLastUpdatedBy(): ?User
    {
        return $this->last_updated_by;
    }

    public function setLastUpdatedBy(?User $last_updated_by): self
    {
        $this->last_updated_by = $last_updated_by;

        return $this;
    }


    /**
     * Triggered on insert
     * @ORM\PrePersist
     */
    public function onPrePersist()
    {
        $this->enabled = true;
        $this->created_at = new \DateTime("now");
        $this->updated_at = new \DateTime();
        $this->roles = 'a:1:{i:0;s:9:"ROLE_USER";}';
    }

    /**
     * Triggered on update
     * @ORM\PreUpdate
     */
    public function onPreUpdate()
    {
        $this->updated_at = new \DateTime("now");
    }
}