如何从其他小部件访问变量

Question

你好我想知道如何从其他小部件访问变量。例如：我希望当我触摸小部件 BotonLogin 的按钮时，它会打印小部件 CamposUsuario 的用户变量。

  class CamposUsuario extends StatelessWidget {
  final String texto;
  CamposUsuario({required this.texto});
  final usuario = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return TextFormField(
      decoration: InputDecoration(
          labelStyle: TextStyle(fontSize: 20), labelText: "$texto"),
      obscureText: (this.texto == "Password") ? true : false,
      controller: usuario,
    );
  }
}

class BotonLogin extends StatelessWidget {
  const BotonLogin({
    Key? key,
  }) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return RaisedButton(
      padding: EdgeInsets.symmetric(horizontal: 60),
      elevation: 7,
      onPressed: () {
        print('si');
      },
      color: Colors.amber[900],
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
      child: Text("Login"),
    );
  }
}

Answer 1

如果你想解决你的问题，那么你需要状态管理。

查看 office 文档以获取状态管理方法列表

https://flutter.dev/docs/development/data-and-backend/state-mgmt/options

Answer 2

您只需将 onPressed 回调传递给您的 BotonLogin 并将 controller 传递给您的 CamposUsuario。然后父控件将使用传递的 TextEditingController 来获取 CamposeUsuario.

的值

示例...

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final TextEditingController usernameController = TextEditingController();
    // UPDATE
    final TextEditingController passwordController = TextEditingController();

    return Scaffold(
      body: Column(
        children: <Widget>[
          CamposUsuario(
            texto: 'Username',
            usuario: usernameController,
          ),
          // UPDATE
          CamposUsuario(
            texto: 'Password',
            usuario: passwordController,
          ),
          BotonLogin(
            onPressed: () {
              print('Si ${usernameController.text}');
              // UPDATE
              print('Password: ${passwordController.text}');
            },
          ),
        ],
      ),
    );
  }
}

class CamposUsuario extends StatelessWidget {
  CamposUsuario({
    required this.texto,
    required this.usuario,
    Key? key,
  }) : super(key: key);

  final String texto;
  final TextEditingController usuario;

  @override
  Widget build(BuildContext context) {
    return TextFormField(
      decoration: InputDecoration(
        labelStyle: const TextStyle(fontSize: 20),
        labelText: texto,
      ),
      obscureText: (this.texto == "Password") ? true : false,
      controller: usuario,
    );
  }
}

class BotonLogin extends StatelessWidget {
  BotonLogin({
    required this.onPressed,
    Key? key,
  }) : super(key: key);

  final VoidCallback onPressed;

  @override
  Widget build(BuildContext context) {
    return ElevatedButton(
      onPressed: onPressed,
      child: Text("Login"),
    );
  }
}

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