Freezed: *.g.dart and fromJson/toJson are not generated after updating to Flutter 1.22.1

[MasterHiei]

Describe the bug
build_runner will remove all generated *.g.dart files and fromJson/toJson code in *.freezed.dart but not regenerate after updating to Flutter 1.22.1.
I tried to discard all file changes but they are not fixed. It works fine on Flutter 1.22.0.

This is my pubspec.yaml file:

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter

  app_review: ^2.0.1
  badges: ^1.1.3
  bloc: ^6.0.3
  bubble: ^1.1.9+1
  cached_network_image: ^2.3.2+1
  camera: ^0.5.8+8
  dartz: ^0.9.2
  data_connection_checker: ^0.3.4
  dio: ^3.0.10
  extended_nested_scroll_view: ^1.0.1
  firebase_core: ^0.5.0+1
  firebase_analytics: ^6.0.2
  firebase_crashlytics: ^0.2.1+1
  fluro: ^1.6.3
  flutter_bloc: ^6.0.6
  flutter_cache_manager: ^1.4.2
  flutter_screenutil: ^3.1.1
  font_awesome_flutter: ^8.10.0
  freezed_annotation: ^0.12.0
  get_it: ^5.0.1
  image_cropper: ^1.3.1
  image_gallery_saver: '^1.6.0'
  image_picker: ^0.6.7+11
  injectable: ^1.0.5
  intl: ^0.16.1
  json_annotation: ^3.1.0
  kt_dart: ^0.8.0
  logger: ^0.9.4
  oktoast: ^2.3.2
  package_info: ^0.4.3
  path: ^1.7.0
  percent_indicator: ^2.1.7+4
  permission_handler: ^5.0.1+1
  photo_view: ^0.10.2
  pull_to_refresh: ^1.6.2
  shared_preferences: ^0.5.12
  sqflite: ^1.3.1+1
  timeago: ^2.0.27
  url_launcher: ^5.7.2
  uuid: ^2.2.2
  webview_flutter: ^1.0.1

dev_dependencies:
  flutter_test:
    sdk: flutter

  build_runner: ^1.10.3
  flutter_launcher_icons: ^0.8.1
  freezed: ^0.12.2
  injectable_generator: ^1.0.6
  json_serializable: ^3.5.0
  mockito: ^4.1.1
  pedantic: ^1.9.2

To Reproduce
I have no idea what happened on my code. I just updated Flutter SDK and some packages like build_runner to the latest version and run flutter pub run build_runner watch --delete-conflicting-outputs as usual.

Expected behavior
Resolve this problem.

[MasterHiei]

update:
Flutter SDK looks like irrelevant. After I downgrade the SDK version to 1.22.0 it still is not working.

[rrousselGit]

What do you mean by they stop generating? Do you have an error?

[MasterHiei]

When I run flutter pub run build_runner watch --delete-conflicting-outputs, all old *.g.dart files and fromJson/toJson methods like below will be deleted, and will be not regenerated.

Model _$ModelFromJson(Map<String, dynamic> json) {
  return _Model.fromJson(json);
}

No error occurred of course.

...
[FINE] json_serializable:json_serializable on lib/model.dart:Running JsonSerializableGenerator - 1 of 2
[FINE] json_serializable:json_serializable on lib/model.dart:Running JsonLiteralGenerator - 2 of 2
...
[INFO] Build:Caching finalized dependency graph...
[INFO] Build:Caching finalized dependency graph completed, took 391ms

[INFO] Build:Succeeded after 57.5s with 196 outputs (2463 actions)

[SEVERE] Watch:
Terminating builds due to package graph update, please restart the build.
[INFO] Watch:Terminating. No further builds will be scheduled

[INFO] Watch:Builds finished. Safe to exit

[MasterHiei]

That's what I did today:

1. update Flutter SDK to 1.22.1
2. update some packages
3. run flutter clean & flutter pub upgrade
4. run flutter pub run build_runner watch --delete-conflicting-outputs
5. issue happened
6. discard all file changes and try step.3~4 again
7. still happened
8. downgrade Flutter SDK to 1.22.0 and try step.3~4 again
9. still happened

[James-A-White]

I'm also seeing this problem. My workaround was to downgrade Flutter, run flutter pub run build_runner watch --delete-conflicting-outputs and then upgrade Flutter. It's not ideal, but should keep development going until a fix has been applied to Freezed.

[MasterHiei]

@James-A-White Thanks for sharing. Well, it's not the best approach but seems not bad. build_runner will cache the previous snapshot unless you clean it up. I guess that's why this problem did not happened when I upgraded to the Flutter 1.22.0.

[rrousselGit]

That's what I did today:

1. update Flutter SDK to 1.22.1
2. update some packages
3. run flutter clean & flutter pub upgrade
4. run flutter pub run build_runner watch --delete-conflicting-outputs
5. issue happened
6. discard all file changes and try step.3~4 again
7. still happened
8. downgrade Flutter SDK to 1.22.0 and try step.3~4 again
9. still happened

I tried that locally and it works for me
The CI also does that and pass
So I'm not sure how to reproduce the issue

[MasterHiei]

@rrousselGit Thank you. That's weird but I'll try to find out more information.

[James-A-White]

Not that it is super helpful, but it will generate the proper files for most of my data classes, but there are a few that just don't work. I've copied one below for your entertainment pleasure.

// Copyright © 2020, InnoVet Europe
// All rights reserved

// package imports
import 'package:freezed_annotation/freezed_annotation.dart';

part 'place_status_request.g.dart';
part 'place_status_request.freezed.dart';

@freezed
abstract class PlaceStatusRequest with _$PlaceStatusRequest {
  const factory PlaceStatusRequest({
    String staffId,
    String accessToken,
    String tapPointId,
    String roomId,
    String floorplanId,
    String buildingId,
    String facilityId,
    String functionId,
    String functionCode,
    String functionStatusId,
    String functionStatusCode,
    String data,
    String topPriorityParams,
    String bottomPriorityParams,
  }) = _PlaceStatusRequest;

  factory PlaceStatusRequest.fromJson(Map<String, dynamic> json) {
    return _$PlaceStatusRequestFromJson(json);
  }
}

[MasterHiei]

Everything works fine on Flutter 1.20.4, build_runner 1.10.1, freezed 0.12.1. All files and methods are generated completely. But it is still broken on Flutter 1.22+, even though use build_runner 1.10.1, freezed 0.12.1.

[MasterHiei]

@rrousselGit Hi👋, I reproduced this issue follow the steps below:

1. create a new flutter project with VSCode(named freezed_test, Flutter: 1.22.1)
2. modify pubspec.yaml to

name: freezed_test
description: A new Flutter project.

publish_to: 'none'

version: 1.0.0+1

environment:
  sdk: ">=2.10.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter

  freezed_annotation: ^0.12.0
  json_annotation: ^3.1.0

dev_dependencies:
  flutter_test:
    sdk: flutter

  build_runner: ^1.10.3
  freezed: ^0.12.2
  json_serializable: ^3.5.0

flutter:
  uses-material-design: true

1. add a new file named test_model.dart
   ```dart:test_model.dart
   import 'package:freezed_annotation/freezed_annotation.dart';

part 'test_model.freezed.dart';
part 'test_model.g.dart';

@freezed
abstract class TestModel with _$TestModel {
const factory TestModel({
String id,
@JsonKey(name: 'test_name') String testName,
}) = _TestModel;

factory TestModel.fromJson(Map json) {
return _$TestModelFromJson(json);
}
}

4. run `flutter pub upgrade`
5. run `flutter pub run build_runner watch --delete-conflicting-outputs`

And then only `test_model.freezed.dart` will be generated without `test_model.g.dart` and `fromJson/toJson` methods.

Log:

[INFO] Generating build script...
[INFO] Generating build script completed, took 356ms

[INFO] Creating build script snapshot......
[INFO] Creating build script snapshot... completed, took 10.8s

[INFO] Watch:Setting up file watchers...
[INFO] Watch:Setting up file watchers completed, took 13ms

[INFO] Watch:Waiting for all file watchers to be ready...
[INFO] Watch:Waiting for all file watchers to be ready completed, took 200ms

[INFO] BuildDefinition:Initializing inputs
[INFO] BuildDefinition:Building new asset graph...
[INFO] BuildDefinition:Building new asset graph completed, took 530ms

[INFO] BuildDefinition:Checking for unexpected pre-existing outputs....
[INFO] BuildDefinition:Checking for unexpected pre-existing outputs. completed, took 1ms

[INFO] Build:Running build...
[INFO] Heartbeat:1.2s elapsed, 0/3 actions completed.
[INFO] Heartbeat:2.3s elapsed, 0/3 actions completed.
[FINE] freezed:freezed on lib/test_model.dart:Running FreezedGenerator
[INFO] Heartbeat:6.4s elapsed, 1/3 actions completed.
[FINE] freezed:freezed on lib/main.dart:Running FreezedGenerator
[FINE] freezed:freezed on test/widget_test.dart:Running FreezedGenerator
[FINE] json_serializable:json_serializable on lib/main.dart:Running JsonSerializableGenerator - 1 of 2
[FINE] json_serializable:json_serializable on lib/main.dart:Running JsonLiteralGenerator - 2 of 2
[FINE] json_serializable:json_serializable on test/widget_test.dart:Running JsonSerializableGenerator - 1 of 2
[FINE] json_serializable:json_serializable on test/widget_test.dart:Running JsonLiteralGenerator - 2 of 2
[FINE] json_serializable:json_serializable on lib/test_model.dart:Running JsonSerializableGenerator - 1 of 2
[FINE] json_serializable:json_serializable on lib/test_model.dart:Running JsonLiteralGenerator - 2 of 2
[INFO] Build:Running build completed, took 12.0s

[INFO] Build:Caching finalized dependency graph...
[INFO] Build:Caching finalized dependency graph completed, took 159ms

[INFO] Build:Succeeded after 12.1s with 1 outputs (11 actions)

Generated freezed file:
```dart
// GENERATED CODE - DO NOT MODIFY BY HAND
// ignore_for_file: deprecated_member_use, deprecated_member_use_from_same_package, use_function_type_syntax_for_parameters, unnecessary_const, avoid_init_to_null, invalid_override_different_default_values_named, prefer_expression_function_bodies

part of 'test_model.dart';

// **************************************************************************
// FreezedGenerator
// **************************************************************************

T _$identity<T>(T value) => value;

/// @nodoc
class _$TestModelTearOff {
  const _$TestModelTearOff();

// ignore: unused_element
  _TestModel call({String id, @JsonKey(name: 'test_name') String testName}) {
    return _TestModel(
      id: id,
      testName: testName,
    );
  }
}

/// @nodoc
// ignore: unused_element
const $TestModel = _$TestModelTearOff();

/// @nodoc
mixin _$TestModel {
  String get id;
  @JsonKey(name: 'test_name')
  String get testName;

  $TestModelCopyWith<TestModel> get copyWith;
}

/// @nodoc
abstract class $TestModelCopyWith<$Res> {
  factory $TestModelCopyWith(TestModel value, $Res Function(TestModel) then) =
      _$TestModelCopyWithImpl<$Res>;
  $Res call({String id, @JsonKey(name: 'test_name') String testName});
}

/// @nodoc
class _$TestModelCopyWithImpl<$Res> implements $TestModelCopyWith<$Res> {
  _$TestModelCopyWithImpl(this._value, this._then);

  final TestModel _value;
  // ignore: unused_field
  final $Res Function(TestModel) _then;

  @override
  $Res call({
    Object id = freezed,
    Object testName = freezed,
  }) {
    return _then(_value.copyWith(
      id: id == freezed ? _value.id : id as String,
      testName: testName == freezed ? _value.testName : testName as String,
    ));
  }
}

/// @nodoc
abstract class _$TestModelCopyWith<$Res> implements $TestModelCopyWith<$Res> {
  factory _$TestModelCopyWith(
          _TestModel value, $Res Function(_TestModel) then) =
      __$TestModelCopyWithImpl<$Res>;
  @override
  $Res call({String id, @JsonKey(name: 'test_name') String testName});
}

/// @nodoc
class __$TestModelCopyWithImpl<$Res> extends _$TestModelCopyWithImpl<$Res>
    implements _$TestModelCopyWith<$Res> {
  __$TestModelCopyWithImpl(_TestModel _value, $Res Function(_TestModel) _then)
      : super(_value, (v) => _then(v as _TestModel));

  @override
  _TestModel get _value => super._value as _TestModel;

  @override
  $Res call({
    Object id = freezed,
    Object testName = freezed,
  }) {
    return _then(_TestModel(
      id: id == freezed ? _value.id : id as String,
      testName: testName == freezed ? _value.testName : testName as String,
    ));
  }
}

/// @nodoc
class _$_TestModel implements _TestModel {
  const _$_TestModel({this.id, @JsonKey(name: 'test_name') this.testName});

  @override
  final String id;
  @override
  @JsonKey(name: 'test_name')
  final String testName;

  @override
  String toString() {
    return 'TestModel(id: $id, testName: $testName)';
  }

  @override
  bool operator ==(dynamic other) {
    return identical(this, other) ||
        (other is _TestModel &&
            (identical(other.id, id) ||
                const DeepCollectionEquality().equals(other.id, id)) &&
            (identical(other.testName, testName) ||
                const DeepCollectionEquality()
                    .equals(other.testName, testName)));
  }

  @override
  int get hashCode =>
      runtimeType.hashCode ^
      const DeepCollectionEquality().hash(id) ^
      const DeepCollectionEquality().hash(testName);

  @override
  _$TestModelCopyWith<_TestModel> get copyWith =>
      __$TestModelCopyWithImpl<_TestModel>(this, _$identity);
}

abstract class _TestModel implements TestModel {
  const factory _TestModel(
      {String id, @JsonKey(name: 'test_name') String testName}) = _$_TestModel;

  @override
  String get id;
  @override
  @JsonKey(name: 'test_name')
  String get testName;
  @override
  _$TestModelCopyWith<_TestModel> get copyWith;
}

[rrousselGit]

Oh, I get what happens

That's because your fromJson syntax is not correct
Do:

  factory TestModel.fromJson(Map<String, dynamic> json) => _$TestModelFromJson(json);

Don't:

  factory TestModel.fromJson(Map<String, dynamic> json) {
    return _$TestModelFromJson(json);
  }

The reason why is because if you use {}, Freezed interprets it as you having a custom fromJson and do not use json_serializable

[MasterHiei]

I got it, thank you!
May be you should add this case to document because some people prefer to use {} rather than =>.