php - Rendering nested category entities from Doctrine 2 -

i'm working self-referencing entity , have build small list structure (<ul><li>) based on entity. however, list must take depth account, need use parent/children relationship base renderer. here's original entity:

<?php  use doctrine\common\collections\arraycollection; use doctrine\common\collections\collection; use doctrine\orm\mapping 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);         }     } } 

i have implemented naive implementation inspired this: https://wildlyinaccurate.com/simple-nested-sets-in-doctrine-2/

however, depth-based padding logic doesn't me <ul><li> structure. recommend way of rendering self-referencing objects html lists?

here how print out 3 levels of unordered categories list () based tree:

<?php $rootcategories = $em->getrepository('entity\category')->findby(['parent' => null]) ?>  // root categories container <ul> <?php foreach ($rootcategories $rootcategory): ?>     <li>         <?= $rootcategory->getname() ?>         <?php if ($rootcategory->getchildren()): ?>             // first child categories container             <ul>                 <?php foreach ($rootcategory->getchildren() $firstchildcategory): ?>                     <li>                         <?= $firstchildcategory->getname() ?>                         <?php if ($firstchildcategory->getchildren()): ?>                             // second child categories container                             <ul>                                 <?php foreach ($firstchildcategory->getchildren() $secondchildcategory): ?>                                     <li><?= $secondchildcategory->getname() ?></li>                                 <?php endforeach ?>                             </ul>                         <?php endif ?>                     </li>                 <?php endforeach ?>             </ul>         <?php endif ?>     </li> <?php endforeach ?> </ul>