将实体与 OneToMany 关联持久化后，外键保持为空答案

【问题标题】：Foreign key stays empty after persisting entity with OneToMany association将实体与 OneToMany 关联持久化后，外键保持为空
【发布时间】：2019-02-14 15:39:52
【问题描述】：

给出以下两个实体类

<?php

namespace App\Entity;

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity()
 * @ORM\Table()
 */
class Tree
{
    /**
     * @ORM\Id()
     * @ORM\Column(type="guid")
     * @ORM\GeneratedValue(strategy="UUID")
     * @var string
     */
    private $id;

    /**
     * @ORM\OneToMany(targetEntity="Apple", mappedBy="tree", cascade={"persist"})
     * @var Collection
     */
    private $apples;

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

    public function toArray(): array
    {
        return [
            'id' => $this->getId(),
        ];
    }

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

    public function setId(string $id): void
    {
        $this->id = $id;
    }

    public function getApples(): Collection
    {
        return $this->apples;
    }

    public function setApples(Collection $apples): void
    {
        $this->apples = $apples;
    }
}

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity()
 * @ORM\Table()
 */
class Apple
{
    /**
     * @ORM\Id()
     * @ORM\Column(type="guid")
     * @ORM\GeneratedValue(strategy="UUID")
     * @var string
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="Tree", inversedBy="apples")
     * @var Tree
     */
    private $tree;

    public function toArray(): array
    {
        return [
            'id' => $this->getId(),
        ];
    }

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

    public function setId(string $id): void
    {
        $this->id = $id;
    }

    public function getTree(): Tree
    {
        return $this->tree;
    }

    public function setTree(Tree $tree): void
    {
        $this->tree = $tree;
    }
}

数据库架构看起来不错，除了 apple.tree_id 可以为空。在这种情况下，这已经是一个问题了吗？

我正在保留如下条目：

<?php

declare(strict_types = 1);

namespace App\Service;

use App\Entity\Apple;
use App\Entity\Tree;
use Doctrine\ORM\EntityManager;

class Gardener
{
    private $entityManager;

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

    public function plantTree(): array
    {
        $entityManager = $this->entityManager;
        $tree          = new Tree();

        $blueApple = new Apple();
        $redApple  = new Apple();
        $tree->getApples()->add($blueApple);
        $tree->getApples()->add($redApple);

        $entityManager->persist($tree);
        $entityManager->flush();

        return (array) $tree;
    }
}

执行持久化和刷新时，没有错误或警告。一棵树和两个苹果条目正在存储，但apple.tree_id 始终为空。

似乎我对实体类的配置有误，但不确定是什么。我也试过添加一个JoinColumn注解@ORM\JoinColumn(name="tree_id", referencedColumnName="id")，但没有任何区别。

我需要进行哪些更改才能正确设置appe.tree_id？

【问题讨论】：

标签： doctrine-orm annotations associations

【解决方案1】：

您缺少*ToMany 端的加法器和删除器功能。

如果您使用 Symfony >4，则将 setApples 函数替换为：

public function addApple(Apple $apple): Tree
{
    $this->apples->add($apple);

    return $this;
}

public function removeApple(Apple $apple): Tree
{
    $this->apples->removeElement($apple);

    return $this;
}

如果您使用的是 Zend Framework 3，请将 setApples 函数替换为：

public function addApples(array $apples): Tree
{
    foreach ($apples as $apple) {
        if (! $this->apples->contains($apple) {
            $this->apples->add($apple)
            $apple->setTree($this);
        }
    }
    return $this;
}

public function removeApples(array $apples): Tree
{
    foreach ($apples as $apple) {
        if($this->apples->contains($apple) {
            $this->apples->remove($apple);
        }
    }
    return $this;
}

阅读 Working with Association 文档，其中显示了示例并解释了如何向后更新“n”。

【讨论】：