ドキュメントや技術記事をみながら作ってみた!

ユーザー登録機能を作るときに、メールアドレスとパスワードを登録する機能しかサンプルが紹介されていないので、公式ドキュメントや過去の技術記事を参考に作ってみた。
状態管理はされていないので、コードは綺麗ではないですが、初学者の学習には最適かなと思いました😅

参考にした情報

Firebaseの情報

キーボードの黄色いエラーの解消方法

開発環境

Flutter3
Firebase CLI こちらは環境構築を済ませておいてください!

FlutterFire公式

先ずは、必要なパッケージをインストールしておく
pubspec.yaml

name: user_add
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 used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.17.3 <3.0.0"

# 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# versions available, run `flutter pub outdated`.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: ^1.0.2
  firebase_core: ^1.19.2
  cloud_firestore: ^3.3.0
  firebase_auth: ^3.4.2

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: ^2.0.0

# 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/assets-and-images/#resolution-aware

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # 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/custom-fonts/#from-packages

main.dart

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'package:user_add/firebase_options.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyAuthPage(),
    );
  }
}

class MyAuthPage extends StatefulWidget {
  @override
  _MyAuthPageState createState() => _MyAuthPageState();
}

class _MyAuthPageState extends State<MyAuthPage> {
  // 入力されたユーザーの名前
  String newUser = "";
  // 入力されたメールアドレス
  String newUserEmail = "";
  // 入力されたパスワード
  String newUserPassword = "";
  // 登録・ログインに関する情報を表示
  String infoText = "";
  // FireStoreにユーザー情報を登録する関数を定義
  CollectionReference users = FirebaseFirestore.instance.collection('users');
  Future<void> Register() {
    // 上で定義したメンバ変数を格納すると、usersコレクションに、
    // メールアドレスとパスワードも保存できる。
    return users
        .add({
          'name': newUser,
          'email': newUserEmail,
          'password': newUserPassword
        })
        .then((value) => print("新規登録に成功"))
        .catchError((error) => print("新規登録に失敗しました!: $error"));
  }

  // メールアドレスとパスワードを登録する関数を定義
  final FirebaseAuth auth = FirebaseAuth.instance;
  Future<void> createAuth() async {
    UserCredential result = await auth.createUserWithEmailAndPassword(
      email: newUserEmail,
      password: newUserPassword,
    );
    final User user = result.user!;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('ユーザー登録'),
      ),
      // キーボードで隠れて、黄色エラーが出るので
      // SingleChildScrollViewで、Centerウイジットをラップする
      body: SingleChildScrollView(
        child: Center(
          child: Container(
            padding: EdgeInsets.all(32),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                // かっこよくしたいので、画像を配置した!
                const CircleAvatar(
                  radius: 75,
                  // images.unsplash.comの画像のパスを貼り付ける
                  backgroundImage: NetworkImage(
                      'https://images.unsplash.com/photo-1658033014478-cc3b36e31a5e?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxlZGl0b3JpYWwtZmVlZHwxMDR8fHxlbnwwfHx8fA%3D%3D&auto=format&fit=crop&w=800&q=60'),
                ),
                const SizedBox(height: 40),
                TextFormField(
                  // テキスト入力のラベルを設定
                  decoration: InputDecoration(labelText: "ユーザー名"),
                  onChanged: (String value) {
                    setState(() {
                      newUser = value;
                    });
                  },
                ),
                const SizedBox(height: 8),
                TextFormField(
                  // テキスト入力のラベルを設定
                  decoration: InputDecoration(labelText: "メールアドレス"),
                  onChanged: (String value) {
                    setState(() {
                      newUserEmail = value;
                    });
                  },
                ),
                const SizedBox(height: 8),
                TextFormField(
                  decoration: InputDecoration(labelText: "パスワード（６文字以上）"),
                  // パスワードが見えないようにする
                  obscureText: true,
                  onChanged: (String value) {
                    setState(() {
                      newUserPassword = value;
                    });
                  },
                ),
                const SizedBox(height: 8),
                ElevatedButton(
                  onPressed: () async {
                    try {
                      // FireStoreにユーザー情報を登録する関数
                      Register();
                      // メール/パスワードでユーザー登録
                      createAuth();
                      // 登録したユーザー情報
                    } catch (e) {
                      // 登録に失敗した場合
                      setState(() {
                        infoText = "登録NG:${e.toString()}";
                      });
                    }
                  },
                  child: Text("ユーザー登録"),
                ),
                const SizedBox(height: 8),
                Text(infoText)
              ],
            ),
          ),
        ),
      ),
    );
  }
}

スクリーンショット

途中からレイアウト変えました😅

やってみた感想

Firebase CLIを使って、iOS、Android、Web３つの異なる環境で動作を確認しましたが、ユーザーの登録はできていました。
なので、問題ないと思われます👏
もっといいコードを書けるようになりたいですね。

Discussion