呈现原则 2 中的嵌套类别实体

Question

我目前正在使用一个自引用实体，我必须基于该实体构建一个小列表结构(<ul><li>(。但是，该列表必须考虑深度，因此我需要使用父/子关系作为渲染器的基础。这是原始实体：

<?php
use DoctrineCommonCollectionsArrayCollection;
use DoctrineCommonCollectionsCollection;
use DoctrineORMMapping as ORM;
/**
 * @ORMEntity()
 * @ORMTable(name="categories")
 */
class Category
{
    /**
     * @ORMId
     * @ORMGeneratedValue(strategy="AUTO")
     * @ORMColumn(type="integer")
     */
    protected $id;
    /**
     * @ORMColumn(type="string", length=255)
     */
    protected $name;
    /**
     * @var Category
     *
     * @ORMManyToOne(targetEntity="Category", inversedBy="children")
     * @ORMJoinColumn(name="category_id", referencedColumnName="id", nullable=true, onDelete="CASCADE")
     */
    protected $parent;
    /**
     * @var Collection
     *
     * @ORMOneToMany(
     *     targetEntity="Category",
     *     mappedBy="parent",
     *     cascade={"ALL"}
     * )
     */
    protected $children;
    public function __construct()
    {
        $this->children = new ArrayCollection();
    }
    public function getId():
    {
        return $this->id;
    }
    public function setId(int $id)
    {
        $this->id = $id;
    }
    public function getName()
    {
        return $this->name;
    }
    public function setName(string $name)
    {
        $this->name = $name;
    }
    public function getParent()
    {
        return $this->parent;
    }
    public function setParent(Category $parent)
    {
        $this->parent = $parent;
    }
    public function setChildren(array $children)
    {
        $this->children = $children;
    }
    public function getChildren()
    {
        return $this->children;
    }
    public function addChild(Category $category)
    {
        if (!$this->children->contains($category)) {
            $category->setParent($this);
            $this->children->add($category);
        }
    }
    public function removeChild(Category $category)
    {
        if ($this->children->contains($category)) {
            $this->children->removeElement($category);
        }
    }
}

受此启发，我实现了一个非常幼稚的实现：https://wildlyinaccurate.com/simple-nested-sets-in-doctrine-2/

但是，这种基于深度的填充逻辑对我<ul><li>结构没有帮助。有没有人推荐任何将自引用对象呈现为 HTML 列表的方法？

Answer 1

以下是打印

出 3 级无序类别列表 (( 的树的方法：

<?php $rootCategories = $em->getRepository('EntityCategory')->findBy(['parent' => null]) ?>
// Root categories container
<ul>
<?php foreach ($rootCategories as $rootCategory): ?>
    <li>
        <?= $rootCategory->getName() ?>
        <?php if ($rootCategory->getChildren()): ?>
            // First child categories container
            <ul>
                <?php foreach ($rootCategory->getChildren() as $firstChildCategory): ?>
                    <li>
                        <?= $firstChildCategory->getName() ?>
                        <?php if ($firstChildCategory->getChildren()): ?>
                            // Second child categories container
                            <ul>
                                <?php foreach ($firstChildCategory->getChildren() as $secondChildCategory): ?>
                                    <li><?= $secondChildCategory->getName() ?></li>
                                <?php endforeach ?>
                            </ul>
                        <?php endif ?>
                    </li>
                <?php endforeach ?>
            </ul>
        <?php endif ?>
    </li>
<?php endforeach ?>
</ul>