Flutter 颤振web，授权后更新导航栏

我正在尝试使用flatter创建一个web应用程序，我有一个问题。经过授权后，我需要更改导航栏中的“登录”按钮，据我所知，我需要更改按钮文本并在导航栏中调用setState，但在我的实现中会引发异常

AuthPage.dart

import 'package:flutter/material.dart';
import 'package:um/pages/home/app_color.dart';
import 'package:um/scripts/api_client.dart';
import 'package:um/scripts/locator.dart';

import 'NavBarDesktop.dart';

class AuthorizationPageDesktop extends StatefulWidget {
  AuthorizationPageDesktop({Key key}) : super(key: key);

  @override
  _AuthorizationPageDesktopState createState() =>
      _AuthorizationPageDesktopState();
}

class _AuthorizationPageDesktopState extends State<AuthorizationPageDesktop> {
  TextEditingController _emailController = TextEditingController();
  TextEditingController _passwordController = TextEditingController();
  bool rememberMe = false;
  ApiClient apiClient = ApiClient.getInstance();
  ScrollController _scrollController = ScrollController();
  PageController _pageController = PageController();

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
        child: Container(
            child: Padding(
      padding: EdgeInsets.only(top: 150, left: 0, right: 0),
      child: Column(
        children: <Widget>[
          Text(
            'Авторизация',
            style: TextStyle(
                fontWeight: FontWeight.w600,
                fontSize: 28,
                color: textPrimaryColor),
          ),
          SizedBox(
            height: 40,
          ),
          _input(Icon(Icons.mail), 'Email', _emailController, false, 15),
          SizedBox(
            height: 15,
          ),
          _input(Icon(Icons.lock), 'Password', _passwordController, true, 15),
          SizedBox(
            height: 5,
          ),
          Container(
              padding: EdgeInsets.only(left: 20, right: 20),
              width: 460,
              child: Theme(
                  data: ThemeData(
                      splashColor: Colors.transparent,
                      highlightColor: Colors.transparent,
                      hoverColor: Colors.transparent),
                  child: CheckboxListTile(
                    title: Text(
                      'Запомнить меня',
                      style: TextStyle(color: textPrimaryColor),
                    ),
                    value: rememberMe,
                    onChanged: (bool value) {
                      setState(() {
                        rememberMe = value;
                      });
                    },
                  ))),
          SizedBox(
            height: 5,
          ),
          _button('Войти', auth, 15),
          SizedBox(
            height: 15,
          ),
          Container(
            width: 460,
            child: Align(
                alignment: Alignment.bottomCenter,
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Text(
                      'Пройдите ',
                      style: TextStyle(color: Colors.white, fontSize: 12),
                    ),
                    Text(
                      'регистрацию, ',
                      style: TextStyle(color: linkColor, fontSize: 12),
                    ),
                    Text(
                      'если вы этого еще не сделали',
                      style: TextStyle(color: Colors.white, fontSize: 12),
                    ),
                  ],
                )),
          ),
          SizedBox(height: 50),
        ],
      ),
    )));
  }

  Widget _input(Icon icon, String hint, TextEditingController controller,
      bool obscure, double borderRadius) {
    return Container(
      width: 460,
      height: 50,
      padding: EdgeInsets.only(left: 20, right: 20),
      child: TextField(
        controller: controller,
        obscureText: obscure,
        style: TextStyle(fontSize: 16, color: Colors.white),
        decoration: InputDecoration(
            border: OutlineInputBorder(),
            isDense: true, // Added this
            contentPadding: EdgeInsets.all(8), //

            hintStyle: TextStyle(
                fontWeight: FontWeight.bold, fontSize: 16, color: Colors.white),
            hintText: hint,
            focusedBorder: OutlineInputBorder(
                borderRadius: BorderRadius.circular(borderRadius),
                borderSide: BorderSide(color: Colors.white, width: 2)),
            enabledBorder: OutlineInputBorder(
                borderRadius: BorderRadius.circular(borderRadius),
                borderSide: BorderSide(color: Colors.white54, width: 1)),
            prefixIcon: Padding(
              padding: EdgeInsets.only(left: 10, right: 10),
              child: IconTheme(
                data: IconThemeData(color: Colors.white),
                child: icon,
              ),
            )),
      ),
    );
  }

  Widget _button(String label, void func(), double borderRadius) {
    return Container(
        width: 460,
        padding: EdgeInsets.only(left: 20, right: 20),
        child: RaisedButton(
          onPressed: () {
            apiClient
                .authorization(_emailController.text, _passwordController.text)
                .then((value) {
              func();
            });
          },
          highlightColor: Theme.of(context).primaryColor,
          color: buttonPrimaryColor,
          child: Text('Войти',
              style: TextStyle(
                  fontWeight: FontWeight.bold,
                  color: textPrimaryColor,
                  fontSize: 16)),
          shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(borderRadius)),
        ));
  }

  void auth() {
    var state = navBar<NavBarDesktop>().navBarState;
    state.update();
  }
}

---

您的_NavBarDesktopState全局密钥需要在_NavBarDesktopState类中初始化，而不是在NavBarDesktop类中初始化。它试图在创建状态之前设置全局键。

类NavBarDesktop扩展StatefulWidget{
class NavBarDesktop extends StatefulWidget {
  NavBarDesktop({Key key}) : super(key: key);
  _NavBarDesktopState navBarState;

  static _NavBarDesktopState of(BuildContext context) {
    assert(context != null);
    final _NavBarDesktopState result =
        // ignore: deprecated_member_use
        context.ancestorStateOfType(const TypeMatcher<_NavBarDesktopState>());
    return result;
  }

  @override
  _NavBarDesktopState createState() {
    navBar.registerLazySingleton(() => this);
    navBarState = _NavBarDesktopState();
    return navBarState;
  }
}


NavBarDesktop（{Key}）：超级（Key:Key）；
_NavBarDesktopState navBarState；
静态（BuildContext上下文）{
断言（上下文！=null）；
最终导航状态结果=
//忽略：不推荐的\u成员\u使用
anteStorStateofType（const TypeMatcher（））；
返回结果；
}
@凌驾
_NavBarDesktopState createState（）{
navBar.registerLazySingleton（（）=>this）；
navBarState=_NavBarDesktopState（）；
返回导航状态；
}
}

Error: setState() called in constructor: _NavBarDesktopState#5e1ee(lifecycle state: created, no widget, not mounted)
This happens when you call setState() on a State object for a widget that hasn't been inserted into the widget tree yet. It is not necessary to   
call setState() in the constructor, since the state is already assumed to be dirty when it is initially created.
    at Object.throw_ [as throw] (http://localhost:50572/dart_sdk.js:4334:11)
    at http://localhost:50572/packages/flutter/src/widgets/widget_span.dart.lib.js:13615:23
    at NavBarDesktop._NavBarDesktopState.new.setState (http://localhost:50572/packages/flutter/src/widgets/widget_span.dart.lib.js:13618:26)      
    at NavBarDesktop._NavBarDesktopState.new.update (http://localhost:50572/packages/um/scripts/router.dart.lib.js:1717:12)
    at AuthPageDesktop._AuthorizationPageDesktopState.new.auth (http://localhost:50572/packages/um/scripts/router.dart.lib.js:1932:13)
    at http://localhost:50572/packages/um/scripts/router.dart.lib.js:1926:15
    at _RootZone.runUnary (http://localhost:50572/dart_sdk.js:37457:58)
    at _FutureListener.then.handleValue (http://localhost:50572/dart_sdk.js:32441:29)
    at handleValueCallback (http://localhost:50572/dart_sdk.js:32988:49)
    at Function._propagateToListeners (http://localhost:50572/dart_sdk.js:33026:17)
    at _Future.new.[_completeWithValue] (http://localhost:50572/dart_sdk.js:32869:23)
    at async._AsyncCallbackEntry.new.callback (http://localhost:50572/dart_sdk.js:32891:35)
    at Object._microtaskLoop (http://localhost:50572/dart_sdk.js:37718:13)
    at _startMicrotaskLoop (http://localhost:50572/dart_sdk.js:37724:13)
    at http://localhost:50572/dart_sdk.js:33243:9

class NavBarDesktop extends StatefulWidget {
  NavBarDesktop({Key key}) : super(key: key);
  _NavBarDesktopState navBarState;

  static _NavBarDesktopState of(BuildContext context) {
    assert(context != null);
    final _NavBarDesktopState result =
        // ignore: deprecated_member_use
        context.ancestorStateOfType(const TypeMatcher<_NavBarDesktopState>());
    return result;
  }

  @override
  _NavBarDesktopState createState() {
    navBar.registerLazySingleton(() => this);
    navBarState = _NavBarDesktopState();
    return navBarState;
  }
}