從原則2呈現嵌套的類別實體

Question

我目前正在使用自引用實體，我必須建立一個基於該實體的小列表結構（<ul><li>）。然而，列表必須考慮到深度，所以我需要使用父/子關係作爲我的渲染器的基礎。這裏的原始實體：

<?php 

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

/** 
* @ORM\Entity() 
* @ORM\Table(name="categories") 
*/ 
class Category 
{ 
    /** 
    * @ORM\Id 
    * @ORM\GeneratedValue(strategy="AUTO") 
    * @ORM\Column(type="integer") 
    */ 
    protected $id; 

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

    /** 
    * @var Category 
    * 
    * @ORM\ManyToOne(targetEntity="Category", inversedBy="children") 
    * @ORM\JoinColumn(name="category_id", referencedColumnName="id", nullable=true, onDelete="CASCADE") 
    */ 
    protected $parent; 

    /** 
    * @var Collection 
    * 
    * @ORM\OneToMany(
    *  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); 
     } 
    } 
} 

我已經實現受此啓發非常幼稚的做法：https://wildlyinaccurate.com/simple-nested-sets-in-doctrine-2/

然而，這種基於深度的填充邏輯不幫我<ul><li>結構。有沒有人推薦任何將自引用對象呈現爲HTML列表的方​​式？

Answer 1

下面是如何打印出3個層次無序類別列表（）的基於樹：

<?php $rootCategories = $em->getRepository('Entity\Category')->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>