导航后流构建器未更新 [英] stream builder is not updating after navigation

问题描述

我正在使用流构建器来检测用户是否登录.

I am using a stream builder to detect if user logged in or not.

 return StreamBuilder<User>(
        stream: AuthService().user,
        builder: (context, snapshot) {
          if (snapshot.hasData)
            return SectionWrapper();
          else
            return Authentication();
        });

这是我正在使用的流

 Stream<User> get user {
    return _auth.onAuthStateChanged.map(_userFromFirebaseUser);
  }
  //create user object based on firebase user
  User _userFromFirebaseUser(FirebaseUser user) {
    return user != null ? User(uid: user.uid, email: user.email) : null;
  }

在部分包装中，有2个按钮可导航到应用程序的两个不同部分，当我在这些部分之一中使用注销方法时，流构建器未更新，并且需要刷新才能更新状态.

in the section wrapper, there are 2 buttons that navigates to two different sections of the app, when I use sign out method in one of these sections, the stream builder is not updating, and it requires refresh to update the state.

我还尝试在部分包装中放置一个按钮以退出，该按钮可以正常工作并更新UI，然后再导航至其中一个部分.

also i tried to put a button in section wrapper to sign out, it works and update UI before I navigate to one of the sections.

这是sectionWrapper()小部件树.

and this is the sectionWrapper() widget tree.

Column(
        children: <Widget>[
          CupertinoButton(
              child: Text('Donation & Selling Section'),
              onPressed: () {
                Navigator.pushReplacementNamed(
                    context, Section1.routeName,
                    arguments: user);
              }),
          CupertinoButton(
              child: Text('Bookstores Section'),
              onPressed: () {
                Navigator.pushReplacementNamed(
                    context, Section2.routeName);
              }),
          
          //works before navigation, does not work after navigation back here
          CupertinoButton(
              child: Text('Sign out'),
              onPressed: () async {
                await AuthService().signOut();
              }),
        ],
      ),

我还尝试对消费者使用流提供程序，但最终遇到了同样的问题.

I also tried to use stream provider with consumer and I ended with the same problem.

   class Wrapper extends StatelessWidget {
  static const String routeName = '/';

  @override
  Widget build(BuildContext context) {
    final user = Provider.of<User>(context);
    return user == null ? Authentication() : SectionWrapper();
  }
}

我用流提供程序包装了材质应用.

I wrapped material app with a stream provider.

MultiProvider(
      providers: [
        StreamProvider<User>.value(value: AuthService().user),
//other providers
      ],
      child: MaterialApp(

推荐答案

您的条件未在子页面中进行测试.您应该在sectionWrapper()页面中调用Provider.of.

Your conditional Is not being tested in the sub page. You should call Provider.of in the sectionWrapper() page.

您是说:

• 如果用户已登录，请构建sectionWrapper小部件
• 如果用户未登录构建身份验证小部件.

就是那个构建方法.构建完成后，您需要说出下一步要做什么.

That is it for that build method. Once that is built, you need to say what you want to do next.

例如.在下一个屏幕的小部件树上方，像您一样设置provider.of.然后，如果值更改，提供程序将强制对该屏幕的构建方法进行重建.

Eg. On the next screen, above your widget tree, set provider.of like you did. Then, if the value changes, provider will force a rebuild for that screen’s build method.

这篇关于导航后流构建器未更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！