🔨
freezed3.0.0をFlutterで試してみた
どんな感じか？
part書かなくていい話題を見たのだが書かないとコンパイラの警告が出る。必要ではないだろうか。記述するコードは減っているように思えるがどうだろうか？
freezedを追加して試してみる。
flutter pub add \
freezed \
freezed_annotation \
--dev build_runner \
--dev json_annotation \
--dev json_serializable
yaml
name: freezed_demo_app
description: "A new Flutter project."
# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev
# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number is used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
# In Windows, build-name is used as the major, minor, and patch parts
# of the product and file versions while build-number is used as the build suffix.
version: 1.0.0+1
environment:
sdk: ^3.7.0
# Dependencies specify other packages that your package needs in order to work.
# To automatically upgrade your package dependencies to the latest versions
# consider running `flutter pub upgrade --major-versions`. Alternatively,
# dependencies can be manually updated by changing the version numbers below to
# the latest version available on pub.dev. To see which dependencies have newer
# versions available, run `flutter pub outdated`.
dependencies:
flutter:
sdk: flutter
# The following adds the Cupertino Icons font to your application.
# Use with the CupertinoIcons class for iOS style icons.
cupertino_icons: ^1.0.8
dev_dependencies:
flutter_test:
sdk: flutter
# The "flutter_lints" package below contains a set of recommended lints to
# encourage good coding practices. The lint set provided by the package is
# activated in the `analysis_options.yaml` file located at the root of your
# package. See that file for information about deactivating specific lint
# rules and activating additional ones.
flutter_lints: ^5.0.0
freezed_annotation: ^3.0.0
build_runner: ^2.4.15
freezed: ^3.0.0
json_annotation: ^4.9.0
json_serializable: ^6.9.4
# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec
# The following section is specific to Flutter packages.
flutter:
# The following line ensures that the Material Icons font is
# included with your application, so that you can use the icons in
# the material Icons class.
uses-material-design: true
# To add assets to your application, add an assets section, like this:
# assets:
# - images/a_dot_burr.jpeg
# - images/a_dot_ham.jpeg
# An image asset can refer to one or more resolution-specific "variants", see
# https://flutter.dev/to/resolution-aware-images
# For details regarding adding assets from package dependencies, see
# https://flutter.dev/to/asset-from-package
# To add custom fonts to your application, add a fonts section here,
# in this "flutter" section. Each entry in this list should have a
# "family" key with the font family name, and a "fonts" key with a
# list giving the asset and other descriptors for the font. For
# example:
# fonts:
# - family: Schyler
# fonts:
# - asset: fonts/Schyler-Regular.ttf
# - asset: fonts/Schyler-Italic.ttf
# style: italic
# - family: Trajan Pro
# fonts:
# - asset: fonts/TrajanPro.ttf
# - asset: fonts/TrajanPro_Bold.ttf
# weight: 700
#
# For details regarding fonts from package dependencies,
# see https://flutter.dev/to/font-from-package
シンプルに使ってみる
main.g.dartは必要なさそう。コードの自動生成は必要なので実行する。マクロなるのがあるそうだが？？？
flutter pub run build_runner watch --delete-conflicting-outputs
値を渡してViewに表示してみる。
main.dart
import 'package:flutter/material.dart';
import 'package:freezed_annotation/freezed_annotation.dart';
part 'main.freezed.dart';
sealed class Usual with _$Usual {
factory Usual({int? a}) = _Usual;
}
// flutter pub run build_runner watch --delete-conflicting-outputs
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatelessWidget {
const MyHomePage({super.key, required this.title});
final String title;
Widget build(BuildContext context) {
List<Usual> usuals = [
Usual(a: 1),
Usual(a: 2),
Usual(a: 3),
];
return Scaffold(
appBar: AppBar(
backgroundColor: Theme.of(context).colorScheme.inversePrimary,
title: Text(title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
...usuals.map((e) => Text(e.a.toString())),
],
),
),
);
}
}
次は、dioを使って、API通信してみよう。いつもと書き方が違っているのに気づいた💡
以前書いた記事でも翻訳したときに気づいたのだが、
Breaking: Freezed classes should now either be abstract, sealed, or manually implements _$MyClass.
Breaking： Freezed クラスは、抽象か、sealed か、手動で _$MyClass を実装する必要があります。
つけないとコンパイラのエラーが出る!
sealedかabstractをつけると消えた!
API通信するときだけど、いつものようにtoJsonとfromJsonは必要です。
こちらが全体のコード:
main.dart
import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:freezed_annotation/freezed_annotation.dart';
import 'package:json_annotation/json_annotation.dart';
part 'main.freezed.dart';
part 'main.g.dart';
abstract class Post with _$Post {
const factory Post({
(0) int id,
('') String title,
}) = _Post;
factory Post.fromJson(Map<String, Object?> json) => _$PostFromJson(json);
}
class DioClient {
DioClient({required this.dio});
final Dio dio;
Future<List<Post>> getPost() async {
try {
final response = await dio.get('https://jsonplaceholder.typicode.com/posts');
final data = response.data;
debugPrint(data.toString());
return [for (var e in data) Post.fromJson(e)];
} catch (e) {
throw Exception(e);
} finally {
dio.close();
}
}
}
// flutter pub run build_runner watch --delete-conflicting-outputs
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatelessWidget {
const MyHomePage({super.key, required this.title});
final String title;
Widget build(BuildContext context) {
final dioClient = DioClient(dio: Dio());
return Scaffold(
appBar: AppBar(
backgroundColor: Theme.of(context).colorScheme.inversePrimary,
title: Text(title),
),
body: FutureBuilder<List<Post>>(
future: dioClient.getPost(),
builder: (context, snapshot) {
return ListView.builder(
itemCount: snapshot.data?.length ?? 0,
itemBuilder: (context, index) {
return Text(snapshot.data?[index].title ?? '');
},
);
},
),
);
}
}
まとめ
使ってみた感想ですが、いつもと同じコードを書いてみて「あれ違うのかな？」と気づかないと何が変わったのかわからなかったですね。Riverpodとfreezedはテンプレートをたくさん作っているのですが、突然破壊的変更が出てしまうので、常に情報を収集する必要がありますね🔍
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