Category tree in a laravel routing - laravel

Question

I am doing a product catalogue with Eloquent and i have 2 models: product and category. Each category can have many products and each product belongs to one category. My category model has the following columns:
id
title
parent_id
slug
and product model has:
id
title
body
category_id
slug
When i am creating a category, by default parent_id set to 0, which means it's not a subcategory, but parent, i.e.:
Cars
--Audi
Cars has parent_id set to 0 and Audi has parent_id set to 1 (because Cars category's id is 1). Then i created model for nested rows:
ItemsHelper.php:
<?php
class ItemsHelper {
private $items;
public function __construct($items) {
$this->items = $items;
}
public function htmlList() {
return $this->htmlFromArray($this->itemArray());
}
private function itemArray() {
$result = array();
foreach($this->items as $item) {
if ($item->parent_id == 0) {
$result[$item->title] = $this->itemWithChildren($item);
}
}
return $result;
}
private function childrenOf($item) {
$result = array();
foreach($this->items as $i) {
if ($i->parent_id == $item->id) {
$result[] = $i;
}
}
return $result;
}
private function itemWithChildren($item) {
$result = array();
$children = $this->childrenOf($item);
foreach ($children as $child) {
$result[$child->title] = $this->itemWithChildren($child);
}
return $result;
}
private function htmlFromArray($array) {
$html = '';
foreach($array as $k => $v) {
$html .= "<ul>";
$html .= "<li>" . $k . "</li>";
if(count($v) > 0) {
$html .= $this->htmlFromArray($v);
}
$html .= "</ul>";
}
return $html;
}
}
then i am printing category hierarchy in a blade file:
{{ $itemsHelper->htmlList() }}
it outputs a category tree. I can access cars category by visiting /category/cars but if it's children of cars category then it should be /category/cars/audi How can i set that in my routes?
routes.php:
Route::resource('category', 'CategoryController');