please read this http://laravel.com/docs/5.1/collections and take a look at sort() or sortBy()

my codes .

 public function categories()
    {
        return $this->hasOne('App\Models\Categories','id');
    }

    public function products()
    {
        return $this->hasMany('App\Models\Products','cat_id');
    }

  public function children()
    {
        return $this->hasMany('App\Models\Categories', 'parent_id', 'id')->with('products')->select(array('id', 'name','slug','parent_id'));
    }




$lastID = explode('-',$id);
        $find = Categories::find(last($lastID));
        if($find['parent_id'] == 0){
            $show = $find->children->toArray();
        }else{
            $products = $find->products->toArray();
            $show     = $find;
        }
        var_dump($show);