3-Level Parent-Children: with() and withCount()

If you have a 3-level structure of parent-children, like categories in an e-shop, and you want to show the number of products on the third level, you can use with('yyy.yyy') and then add withCount() as a condition

class HomeController extend Controller
{
    public function index()
    {
        $categories = Category::query()
            ->whereNull('category_id')
            ->with(['subcategories.subcategories' => function($query) {
                $query->withCount('products');
            }])->get();
    }
}

class Category extends Model
{
    public function subcategories()
    {
        return $this->hasMany(Category::class);
    }
 
    public function products()
    {
        return $this->hasMany(Product::class);
    }
}

<ul>
    @foreach($categories as $category)
        <li>
            {{ $category->name }}
            @if ($category->subcategories)
                <ul>
                @foreach($category->subcategories as $subcategory)
                    <li>
                        {{ $subcategory->name }}
                        @if ($subcategory->subcategories)
                            <ul>
                                @foreach ($subcategory->subcategories as $subcategory)
                                    <li>{{ $subcategory->name }} ({{ $subcategory->product_count }})</li>
                                @endforeach
                            </ul>
                        @endif
                    </li>
                @endforeach
                </ul>
            @endif
        </li>
    @endforeach
</ul>