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我有这个工会：

@freezed
abstract class VeganItem extends VeganItemAbstraction with _$VeganItem {
  @With(GroceryItemMixin)
  const factory VeganItem.groceryItem(
      {int? id,
      String? name,
      String? companyName,
      String? description,
      List<Option>? tags,
      int? rating,
      List<ImagePickerImage>? images}) = GroceryItem;..........

中还有 4 个其他亚型VeganItem。

我有这个联合类型，其中包含VeganItem：

@freezed
abstract class VeganItemEstablishment extends VeganItemEstablishmentAbstraction
    with _$VeganItemEstablishment {
  @With(GroceryItemEstablishmentMixin)
  const factory VeganItemEstablishment.groceryItemEstablishment(
      {int? id,
      Establishment? establishment,
      GroceryItem? veganItem,
      double? price,}) = GroceryItemEstablishment;..............

当我GroceryItemEstablishment.veganItem成为 typeVeganItem时，我可以像这样使用 copywith：

  mvipVm.entity =
      mvipVm.entity!.copyWith.veganItem!(id: null, images: null);

但是当我使它成为 type 时GroceryItem，我必须像这样使用 copywith：

  mvipVm.entity = mvipVm.entity!.map(
    groceryItemEstablishment: (value) => value.copyWith(
        veganItem: mvipVm.entity!.veganItem!
            .copyWith(id: null, images: null) as GroceryItem),
    menuItemEstablishment: (value) => value.copyWith(
        veganItem: mvipVm.entity!.veganItem!
            .copyWith(id: null, images: null) as MenuItem),
    restaurantItemEstablishment: (value) => value.copyWith(
        veganItem: mvipVm.entity!.veganItem!
            .copyWith(id: null, images: null) as RestaurantItem),
    eventItemEstablishment: (value) => value.copyWith(
        veganItem: mvipVm.entity!.veganItem!
            .copyWith(id: null, images: null) as EventItem),
    groceryStoreItemEstablishment: (value) => value.copyWith(
        veganItem: mvipVm.entity!.veganItem!
            .copyWith(id: null, images: null) as GroceryStoreItem),
  );

文档提到该字段必须在所有子类型上才能在copyWith. 但是如果有相同的字段但有不同的子类型呢？

是否有替代解决方案可以GroceryItemEstablishment.veganItem让我在字段中输入子类型以提供更简洁的copyWith语法？

编辑：到目前为止，另一种选择是保留veganItem为超类型（VeganItem），并GroceryItem在必要时将其强制转换为子类型（），这样更易​​于管理。

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