get_special_discount_amount null

backend/order/serializers.py

@@ -83,8 +83,8 @@ class OrderItemSerailzier(serializers.ModelSerializer):
         if amount is None:
             # If it's an order item, check item_special_discount_amount property
             amount = getattr(obj, 'item_special_discount_amount', 0)
-        if amount is None:
+        if amount is None or amount == 0:
-            amount = 0
+            return None
         return f'{int(amount):,.0f} تومان'