FlutterDart：子类化冻结的数据类

我正在使用以下插件:https://pub.dev/packages/freezed

我想对冻结的数据类进行子类化，以便在我的数据层中提供额外的功能.

import 'dart:ui';
import 'package:freezed_annotation/freezed_annotation.dart';
part 'card.freezed.dart';

@freezed
abstract class Card with _$Card {
  factory Card({String text, Color color, List<String> categories}) = _Card;
}

现在我想把这个Card类作为CardModel的一个超类，这样CardModel就可以访问相同的字段、copyWith方法、值相等等等...

import 'package:flutter/widgets.dart';
import 'package:growthdeck/features/card_deck/domain/entities/card.dart';

import '../../domain/entities/card.dart';

abstract class CardModel extends Card {
  factory CardModel.fromMap(Map<String, dynamic> card) => Card(
        text: card["text"],
        color: Color(int.parse(card['color'])),
        categories: card['categories'] as List<String>,
      );
}

这会引发以下错误:

package:growthdeck/features/card_deck/data/models/card_model.dart 11:9  new CardModel.fromMap
test/features/card_deck/data/models/card_model_test.dart 13:23          main.<fn>

type '_$_Card' is not a subtype of type 'CardModel' in type cast

有没有办法把这件事做好呢？我的解决方法是简单地将Card类"包装"在CardModel中，并提供一个不太优雅的toCard()方法:s