【Flutter】FirebaseにREST APIで接続する(全OS対応)

dependencies:
  firebase_auth_rest: ^2.0.0
  firebase_database_rest: ^1.0.2 # ★必須ではない。Databaseと接続する際に必要。
  flutter_dotenv: ^3.1.0 # ★必須ではない。本記事では、APIKEYを.envファイルから取得するため必要。

APIKEY='ここにAPIキーを書いておく'

Future<void> main() async {
  await DotEnv.load(fileName: '.env'); // <-追加
  runApp(MyApp());
}

final apiKey = env['APIKEY'];

class SignUpPage extends StatefulWidget {
  @override
  _SignUpPageState createState() => _SignUpPageState();
}

class _SignUpPageState extends State<SignUpPage> {
  var emailTextEditingController = TextEditingController();
  var passwordTextEditingController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('新規登録ページ'),
        centerTitle: true,
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Container(
              margin: EdgeInsets.all(20),
              child: TextField(
                controller: emailTextEditingController,
                maxLength: 30,
                decoration: const InputDecoration(
                  icon: Icon(Icons.mail),
                  hintText: 'メールアドレスを入力してください',
                  labelText: 'メールアドレス *',
                ),
              ),
            ),
            Container(
              margin: EdgeInsets.all(20),
              child: TextField(
                controller: passwordTextEditingController,
                maxLength: 15,
                obscureText: true,
                decoration: const InputDecoration(
                  icon: Icon(Icons.lock),
                  hintText: 'パスワードを入力してください',
                  labelText: 'パスワード *',
                ),
              ),
            ),
            ElevatedButton(
              onPressed: () => SignUpWithPassword(),
              child: Text('登録する'),
            )
          ],
        ),
      ),
    );
  }
}

  /// E-mail/Passで新規登録
  Future<void> SignUpWithPassword() async {
    final client = Client();
    final apiKey = env['APIKEY'];
    try {
      final fbAuth = FirebaseAuth(client, apiKey, 'ja-JP');
      final account = await fbAuth.signUpWithPassword(emailTextEditingController.text, passwordTextEditingController.text);
      final accountInfo = await account.getDetails();

      await Navigator.popAndPushNamed(context, '/account_info', arguments: accountInfo);

    } catch (e) {
      print(e);
    } finally {
      print('Clientをクローズします。');
      client.close();
    }
  }