i need a dropdown list based on parent using laravel5

controller

public function siteadmin_get_subcategory(Request $request)
    {

    $product_id = $request->input('product');   

      $sub_category=array(

               'product_id'=>$product_id,
               );
     $return = Category_model::get_subcategory($sub_category);       
    //return view('siteadmin.get-subcategory',['sub_category' => $sub_category]);
    return view('siteadmin.get-subcategory',['sub_category' => $sub_category]);

    }

model

public static get_subcategory($sub_category) { return DB::table('le_product')->where('product_id', '=', $sub_category)->get();

    }

views

this is my ajax concept for dropdownlist
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js">       </script>  

 <script>
 $(document).ready(function(){
$('#product_id').change(function(){
    var product = $('#product_id').val();
    if(product != 0)
    {
        $.ajax({
            type:'post',
            url:"<?php echo       base_url('SiteadminController/siteadmin_getsub_category')?>",
            data:{id:product},
            cache:false,
            success: function(returndata){
                $('#subcategory').html(returndata);
            }
        });
    }
})

})

via Chebli Mohamed