[REFACTOR] Added cart_id in auth user serializer

authentication/serializers.py

@@ -25,8 +25,10 @@ class UserAuthSerializer(serializers.ModelSerializer):
 
         if instance.cart.exists():
             result['transaction_status'] = instance.cart.last().transaction_status
+            result['cart_id'] = instance.cart.last().id
         else:
             result['transaction_status'] = None
+            result['cart_id'] = None
 
         return result