Laravel Session不更新关联数组值

I am updating my current session array value but its not updating.

Scenario: My controller called by ajax request and then pass qty, product price. On my cart page i have qty increment and decrements button. Ajax call is executed on click of increment or decrements button. .On every increment or decrements of qty ajax request is executed.If we will add more than two products in cart then session value is not updated.

For e.g-: If user update the qty of first product every thing is update correctly in session but if we update the second product quantity then the first product qty will be the same as its was initially and second product qty is updated.

So session value is not preserved.

Below is code

public function updateCart(Request $request){

  $data = $request->input(); //to get the post data from ajax

   $order        = $request->session()->get('order');
   $orderDetails = $request->session()->get('order_detail');


    $order['grand_total']=$data['grandtotal'];

    //$request->session()->push($orderDetails[$data['productId']]['product_quantity'], $data['qty']);

 $orderDetails[$data['productId']]['product_quantity']=$data['qty'];

$orderDetails[$data['productId']]['total_product_price'] = $data['totalProductPrice'];

      $request->session()->put('order', $order);
      $request->session()->put('order_detail', $orderDetails);



    $order        = $request->session()->get('order');
    $orderDetails = $request->session()->get('order_detail');

                      ;
     echo "<pre>"; print_r($orderDetails);  exit;

             return response()->json(['status' => 'success', 'response' => true,'data'=>'Logs written successfully']);


        }

Below is my array structure

Array
(
    [cf9e57dc-6923-d774-f61f-40022a82e07b] => Array
        (
            [product_name] => EGG
            [product_id] => cf9e57dc-6923-d774-f61f-40022a82e07b
            [product_quantity] => 1
            [product_description] => 
            [price] => 30
            [preparation_time] => 00:05:00
            [company_id] => 897e4562-03b5-9259-5e65-fa525dc4258d
            [store_id] => 8754f65d-3e25-bfcd-5b82-7b7d76b3fc2c
            [delivery_date] => 2018-12-19
            [total_product_price] => 30
        )

    [bfcb777b-acbf-c4d4-aa1f-1cbe57c6e880] => Array
        (
            [product_name] => burger
            [product_id] => bfcb777b-acbf-c4d4-aa1f-1cbe57c6e880
            [product_quantity] => 3
            [product_description] => 
            [price] => 20
            [preparation_time] => 00:10:00
            [company_id] => 897e4562-03b5-9259-5e65-fa525dc4258d
            [store_id] => 8754f65d-3e25-bfcd-5b82-7b7d76b3fc2c
            [delivery_date] => 2018-12-19
            [total_product_price] => 60
        )

)

Below is my ajax code

function updateCart(qty,productId,totalProductPrice,grandtotal){

   var url= $('#baseUrl').val()+"/updateCart";

      $.ajaxSetup({
                    headers: {
                        'X-CSRF-TOKEN': $("input[name=_token]").val()
                    }
                });

      $.ajax({
                    url: url,
                    data: {'qty': qty, 'productId':productId, 'totalProductPrice':totalProductPrice,
                            'grandtotal':grandtotal  },
                    type: 'POST',
                    datatype: 'JSON',

                    success: function (response) {
                        if (response.status === 'success') {
                            console.log(response.data);
                            //$('#myModalCallback').modal('toggle');
                        } else {
                            //alert('Issue');
                        }
                    },
                    error: function (response) {
                        $('#errormessage').html(response.message);
                    }
                });


  }

Thanks in Advnace