Flutter“ChangeNotifierProxyProvider 有错误。错误：“未定义命名参数“builder”。”

Question

main.dart 文件 ChangeNotifierProxyProvider 存在问题，未定义构建器方法。

 ChangeNotifierProxyProvider<Auth, Orders>(
      builder: (ctx, auth, previousOrders) => Orders(
        auth.token,
        auth.userId,
        previousOrders == null ? [] : previousOrders.orders,
      ),
    ),

Answer 1

ChangeNotifierProxyProvider<Auth, Products>(
      create: (_) => Products('', '', []),
      update: (_, auth, prevProducts) {
        return Products(
          auth.token,
          auth.userId,
          prevProducts == null ? [] : prevProducts.items,
        );
      },
    ),