[7.x] fix: make it possible to update order from Gateway::callback (#1240)

* fix: make it possible to update order from Gateway::callback

fixes #1237

* fix: use $order->fresh() to refetch the order

This prevents creating a new order instance if it initially was created from cart.

* Don't need a comment here.

---------

Co-authored-by: Duncan McClean <duncan@doublethree.digital>

Author: RafaelKr

src/Http/Controllers/GatewayCallbackController.php

@@ -18,11 +18,9 @@ class GatewayCallbackController extends BaseActionController
 
     public function index(Request $request, $gateway)
     {
-        if ($request->has('_order_id')) {
-            $order = Order::find($request->get('_order_id'));
-        } else {
-            $order = $this->getCart();
-        }
+        $order = $request->has('_order_id')
+            ? Order::find($request->get('_order_id'))
+            : $this->getCart();
 
         $gatewayName = $gateway;
 
@@ -40,11 +38,15 @@ public function index(Request $request, $gateway)
             $callbackSuccess = $order->paymentStatus() === PaymentStatus::Paid;
         }
 
+        $order->fresh();
+
         if (! $callbackSuccess) {
             return $this->withErrors($request, "Order [{$order->get('title')}] has not been marked as paid yet.");
         }
 
-        $order->status(OrderStatus::Placed)->save();
+        if ($order->status() !== OrderStatus::Placed) {
+            $order->status(OrderStatus::Placed)->save();
+        }
 
         $this->forgetCart();