Flutter 使用状态（ScopedModels）在单个屏幕上显示登录或注册表单

我想为注册和登录使用一个身份验证屏幕。我使用state根据用户的输入显示相应的表单。我有一个名为SignView的父窗口小部件类和一个名为auth_form_widgets.dart的子窗口小部件auth_form_widgets.dart处理表单布局和验证，而SignView根据来自模型（SignModel）的值构建UI

我有两个问题：

这是一个好方法吗？我想我没有看到任何教程建议这样做。我这样做只是为了更好地掌握颤振中的状态管理

我现在注意到的是，当我从注册切换到登录（或返回）时，输入到一个表单字段中的值在另一个表单上仍然可见

登录视图代码：

return ScopedModel<SignModel>(
      model: locator<SignModel>(),
      child: ScopedModelDescendant<SignModel>(
          builder: (context, child, model) => Scaffold(
                appBar: AppBar(
                  centerTitle: true,
                  title: Text(
                    model.title,
                    style: Theme.of(context).textTheme.headline1,
                  ),
                ),
                body: GestureDetector(
                  onTap: () {
                    FocusScope.of(context).unfocus();
                  },
                  child: Column(
                    children: [
                      Expanded(
                          flex: 7,
                          child: Container(
                              height: screenHeightPercentage(context,
                                  percentage: 0.8),
                              child: model.activeForm)),

Widget signIn() {
  return ScopedModelDescendant<SignModel>(
    builder: (context, child, model) => Container(
      padding: EdgeInsets.only(top: 25, bottom: 10, left: 30, right: 30),
      alignment: Alignment.topCenter,
      decoration: BoxDecoration(
        color: Colors.white,
      ),
      child: Builder(
          builder: (context) => Form(
                key: _formKey,
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    Opacity(opacity: .5, child: emailField()),
                    SizedBox(
                      height: 25,
                    ),
                    Opacity(opacity: .5, child: passwordField()),
                    SizedBox(
                      height: 25,
                    ),
                    Container(
                      child: ConstrainedBox(
                        constraints:
                            BoxConstraints.tightFor(width: 370, height: 65),
                        child: ElevatedButton(
                            style: ElevatedButton.styleFrom(
                              primary: Colors.green,
                              onPrimary: Colors.white,
                              shape: RoundedRectangleBorder(
                                borderRadius: BorderRadius.circular(10.0),
                              ),
                            ),
                            onPressed: () {},
                            child: Text(
                              'Sign in',
                              style: TextStyle(fontSize: 18),
                            )),
                      ),
                    ),
                    SizedBox(
                      height: 25,
                    ),
                    Center(
                      child: Container(
                        child: RichText(
                          text: TextSpan(children: [
                            TextSpan(
                                text: 'New here? Register.',
                                style: Theme.of(context).textTheme.bodyText2,
                                recognizer: TapGestureRecognizer()
                                  ..onTap = () {
                                    model.displayForm();
                                  }),
                            TextSpan(
                              text: '     ',
                            ),
                            TextSpan(
                                text: '  Forgot Password?',
                                style: Theme.of(context).textTheme.bodyText2,
                                recognizer: TapGestureRecognizer()
                                  ..onTap = () {}),
                          ]),
                        ),
                      ),
                    )
                  ],
                ),
              )),
    ),
  );
}

  Widget displayForm() {
    if (_setUserStatus() == true) {
      notifyListeners();
      activeForm = signUp();
      title = 'Sign up';
      
    } else {
      notifyListeners();
      activeForm = signIn();
      title = 'Sign in';
   
    }
    return activeForm;
  }
}