flutter : freezed required nor marked with @Default

Question

I am trying to use freezed on my application, So I added

environment:
  sdk: ">=2.7.0<3.0.0"

  freezed: ^0.14.0
  freezed_annotation: ^0.14.0

to my dependencies.

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

After that I create simple freezed class :

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;
}

But I got this error:

[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,

this is flutter doctor:

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.

My project is not null safety and I want to use freezed in non null safety state.

Answer 1

This would give me the same error:

const factory FamilyModel(
    int page,
    int per_page,
    int pages,
    int total_items,
    @Default([]) List<FamilyMemberModel> familyMembers,
  ) = _FamilyModel;

But in this way I fixed it:

const factory FamilyModel(
    int page,
    int per_page,
    int pages,
    int total_items, {
    @Default([]) List<FamilyMemberModel> familyMembers,
  }) = _FamilyModel;

In substance, the @Default param must be in between the { } so that the compiler knows that it's optional and (in that case) can be replaced by @Default([])

Answer 2

Add required before items, or you can make it nullable using String? or provide default value like @Default("") String icon,

@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;
}