flutter : freezed或标记为@Default

Question

我正尝试在我的应用程序上使用freezed，所以我添加了

environment:
  sdk: ">=2.7.0<3.0.0"

  freezed: ^0.14.0
  freezed_annotation: ^0.14.0

对我的依赖。

dev_dependencies:
  freezed_annotation: ^0.12.0
  build_runner:  ^2.0.1
  retrofit_generator:
  flutter_localizations:
    sdk: flutter
  flutter_test:
    sdk: flutter

在那之后，我创建了简单的冻结类：

import 'package:freezed_annotation/freezed_annotation.dart';

part 'chart_daily_expanded_detailes_model.freezed.dart';

@freezed
abstract class ChartDailyExpandedDetailesModel
    with _$ChartDailyExpandedDetailesModel {
  const factory ChartDailyExpandedDetailesModel({
    String title,
    String testNumber,
    String testPercentage,
    String icon,
  }) = _ChartDailyExpandedDetailesModel;
}

但是我得到了这个错误：

[SEVERE] freezed:freezed on lib/new_develop/model/test/chart_daily_expanded_detailes_model.dart:

The parameter `title` of `ChartDailyExpandedDetailesModel` is non-nullable but is neither required nor marked with @Default
package:app/new_develop/model/test/chart_daily_expanded_detailes_model.dart:9:12
  ╷
9 │     String title,

我是颤动医生：

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.2.3, on Linux, locale en_US.UTF-8)
[!] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    ✗ Android license status unknown.
      Run `flutter doctor --android-licenses` to accept the SDK licenses.
      See https://flutter.dev/docs/get-started/install/linux#android-setup for more details.
[✓] Chrome - develop for the web
[✓] Android Studio (version 4.2)
[✓] Android Studio
[✓] VS Code (version 1.60.0)
[✓] Connected device (2 available)

! Doctor found issues in 1 category.

我的项目不是空安全的，我想在非空安全状态下使用freezed。

Answer 1

在项之前添加required，或者可以使用String?或提供默认值(如@Default("") String icon, )使其可为空

@freezed
abstract class ChartDailyExpandedDetailesModel
    with _$ChartDailyExpandedDetailesModel {
  const factory ChartDailyExpandedDetailesModel({
    required String title,
    required String testNumber,
     String? testPercentage, //nullable item
    @Default("") String icon, //contain default value
  }) = _ChartDailyExpandedDetailesModel;
}