How to get related products in a laravel-nestedset?

Laravel 5.7

---

in Category model:

  public function parent()
  {
    $parent =  $this->belongsTo('App\Category', 'parent_id');
    return $parent;
  }

  public function children()
  {
    return  $this->hasMany('App\Category', 'parent_id');
  }



  public function product()
  {
        return $this->belongsToMany(Product::class);
  }

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

I created a nested category like this:

Root > Cat1 > cat2 > Cat3

Now I added a product to cat3.

how can I get all products via cat1 or root?

I tried these:

this code works (it return me related product)

if($cat3->products()->count()) // it return true number

For this (its parent):

if($cat2->products()->count()) // it return false number

But for this:

if($cat1->products()->count()) // it always return 0

And this

if($root->products()->count()) // it always return 0

what is my wrong?

via Chebli Mohamed