how show nested relation in laravel resource - laravel

Question

I have Category Model that has one to many relation with itself.
It means each category has many children and each child has many products.
Now, I want to show parent categories (it means parent_id is null) with all products (list of products of all children).
Each product has category_id that category is child.
What is the best way to handle this in Laravel resources?
Category Model
class Category extends Model
{
public function products()
{
return $this->hasMany('App\Models\Products', 'category_id', 'id');
}
public function children()
{
return $this->hasMany('App\Models\Category', 'parent_id', 'id');
}
}
My Query:
$categories = Category::select(['id', 'name'])
->where('parent_id', '=', null)
->with(['children' => function ($query){
$query->select(['id']);
$query->with('products:id,title,description,banner');
}])
->orderBy('id', 'desc')
->get();
And Resource:
public function toArray($request)
{
return [
'id' => $this->id,
'category' => $this->name,
'products' => [],
];
}
I tried many different ways to show products, none of them has worked so far.

Answer 1

I used hasManyThrough relation to get all product of each main category
Relation function:
public function childrenproducts() {
return $this->hasManyThrough( Product::class, Category::class , 'parent_id', 'category_id' );
}
Query:
$categories = Category::select(['id', 'name'])
->where('parent_id', '=', null)
->has('childrenproducts', '>=', 1)
->with(['childrenproducts' => function ($query) {
$query->select(['products.id', 'products.title', 'products.description', 'products.banner']);
$query->orderBy('products.id', 'desc');
}])
->orderBy('id', 'desc')
->get();
Resource:
public function toArray($request)
{
return [
'id' => $this->id,
'category' => $this->getName(),
'products' => ProductResource::collection($this->whenLoaded('childrenproducts'))
];
}