create nested droptown using laravel admin panel

Question

i have a table buss_catgry_mst fields:- buss_catgry_mst_id , category_name ,parent_id, depth.

i want to create nested category using select_2_nested in backpack laravel. ex:- buss_catgry_mst_id=1 , category_name=restaurent ,parent_id=0, depth=1.

i want to create it's sub category and i want to take depth value which is +1 from it's main category depth value.

code in crud controller:-

  {
      CRUD::setValidation(StoreRequest::class); 
//for nested

      CRUD::addField([
          'name' => 'parent_id',
          'label'     => "Category",
          'type'      => 'select2_nested',
          'entity'    => 'category', // the method that defines the relationship in your Model
          'attribute' => 'category_name', // foreign key attribute that is shown to user
          'model'     => "App\Models\BussCatgryMst",
          


      ]);   ```

***model buss_catgry_mst***

public function category()
      {
          return $this->hasMany(BussCatgryMst::class);
      }  

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