Question

我是Flutter的新手，正在尝试通过登录和注册来构建身份验证系统。
我遵循了在线教程，一切正常。但是我的身份验证流程略有不同，并且当我添加额外的步骤时，“登录”或“注册”屏幕请勿重定向到首页登录页面。

这是教程中的代码，可以正常工作。您会注意到，启动应用程序时，出现的第一个屏幕是Wrapper.dart通过IF STATE调用的登录。

这里是教程中的文件：
教程main.dart

void main() {
  runApp(Main());
}

class Main extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StreamProvider<User>.value(
        value: AuthService().user,
        child: MaterialApp(
          home: Wrapper(),
          debugShowCheckedModeBanner: false,
        )
      );
  }
}

教程wrapper.dart

class Wrapper extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final user = Provider.of<User>(context);

    // return either Home or Auth widget
    if (user == null) {
      return Authenticate();
    } else {
      return Home();
    }
  }
}

教程authenticate.dart

class Authenticate extends StatefulWidget {
  @override
  _AuthenticateState createState() => _AuthenticateState();
}

class _AuthenticateState extends State<Authenticate> {
  bool showSignIn = true;
  void toggleView() {
    setState(() => showSignIn = !showSignIn);
  }

  @override
  Widget build(BuildContext context) {
    if (showSignIn) {
      return SignIn(toggleView: toggleView);
    } else {
      return Register(toggleView: toggleView);
    }
  }
}

教程signIn.dart

class SignIn extends StatefulWidget {
  final Function toggleView;
  SignIn({this.toggleView});

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

class _SignInState extends State<SignIn> {
  final AuthService _auth = AuthService();
  final _formKey = GlobalKey<FormState>();
  bool loading = false;

  // text Field State
  String email = '';
  String password = '';
  String error = '';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
            backgroundColor: Colors.brown[400],
            elevation: 0.0,
            title: Text('Sign in'),
            actions: <Widget>[
              FlatButton.icon(
                icon: Icon(Icons.person),
                label: Text('Register'),
                onPressed: () {
                  widget.toggleView();
                },
              )
            ]),
        body: Container(
            padding: EdgeInsets.symmetric(vertical: 20.0, horizontal: 50.0),
            child: Form(
                key: _formKey,
                child: Column(children: <Widget>[
                  SizedBox(height: 20.0),
                  TextFormField(
                    decoration: textInputDecoration.copyWith(hintText: 'Email'),
                    validator: (val) => val.isEmpty ? 'Enter an email' : null,
                    onChanged: (val) {
                      setState(() => email = val);
                    },
                  ),
                  SizedBox(height: 20.0),
                  TextFormField(
                    obscureText: true,
                    decoration:
                        textInputDecoration.copyWith(hintText: 'Password'),
                    validator: (val) => val.length < 6
                        ? 'Password is too short. Min 6 characters long'
                        : null,
                    onChanged: (val) {
                      setState(() => password = val);
                    },
                  ),
                  SizedBox(height: 20.0),
                  RaisedButton(
                    color: Colors.pink[400],
                    child: Text(
                      'Sign in',
                      style: TextStyle(color: Colors.white),
                    ),
                    onPressed: () async {
                      if (_formKey.currentState.validate()) {
                        setState(() => loading = true);

                        dynamic result = await _auth.signInWithEmailAndPassword(
                            email, password);
                        if (result == null) {
                          setState(() {
                            error =
                              'These credentials are invalid. Please check them and try again!';
                            loading = false;
                          });
                        }
                      }
                    },
                  ),
                ]))
            ));
  }
}

Registration.dart文件与SignIn类似，因此在此不再显示。
最后要记录的文件是名为 AuthService.dart

的服务。

class AuthService {
  final FirebaseAuth _auth = FirebaseAuth.instance;

  // Create user object based on FirebaseUser
  User _userFromFirebaseUser(FirebaseUser user) {
    return user != null ? User(uid: user.uid) : null;
  }

  // Auth change user stream
  Stream<User> get user {
    return _auth.onAuthStateChanged.map(
        _userFromFirebaseUser); // This is the equivalent of .map((FirebaseUser user) => _userFromFirebaseUser(user));
  }

  // SignIn with Email & Password
  Future signInWithEmailAndPassword(String email, String password) async {
    try {
      AuthResult result = await _auth.signInWithEmailAndPassword(
          email: email, password: password);
      FirebaseUser user = result.user;
      return _userFromFirebaseUser(user);
    } catch (e) {
      print(e.toString());
      return null;
    }
  }

}

让我解释一下以上流程的工作原理
用户启动应用程序时，main.dart文件将调用wrapper.dart，该文件将检查User是否为空或存在。
如果为User=null，则表示它尚未登录并调用Authenticate.dart，默认情况下会打开SignIn屏幕。
如果为User != null，则表示用户已登录并调用Home.dart屏幕。

******我的问题*****
现在，在我的流程中（见下文），Wrapper在StartAuthButtons.dart时调用User=null。
StartAuthButtons有几个按钮，可通过不同的方法（例如Google，Facebook，Apple和通过电子邮件/密码）对用户进行身份验证。

MY Wrapper.dart ：

class Wrapper extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final user = Provider.of<User>(context);

    if (user == null) {
      return StartAuthButtons();
      //return Authenticate(); <-- this was before
    } else {
      return Home();
    }
  }
}

一旦用户单击“使用电子邮件和密码登录”，我将使用Flutter Navigate进入“登录”页面。这是我与本教程不同的额外步骤。（请在星号之间的以下代码中检查我的评论）
我的 StartAuthButtons.dart

class StartAuthButtons extends StatefulWidget {
  @override
  _StartAuthButtonsState createState() => _StartAuthButtonsState();
}

class _StartAuthButtonsState extends State<StartAuthButtons> {
  final AuthService _auth = AuthService();

  @override
  Widget build(BuildContext context) {
    return Stack(children: [
            AuthLayout(),
            Scaffold(
                backgroundColor: Colors.transparent,
                appBar: AppBar(
                  title: Center(child: Text('Welcome')),
                  backgroundColor: Colors.transparent,
                ),
                body: SingleChildScrollView(
                  child: ConstrainedBox(
                    constraints: BoxConstraints(),
                    child: Center(
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.start,
                        children: <Widget>[

                          //Email & Password SignIn
                          Padding(
                            padding: EdgeInsets.all(8.0), child: new MaterialButton(
                              child: SignInEmailPasswordBtn(),
                              onPressed: () {
                                ****** I THINK THE ISSUE IS HERE *********
                                Navigator.push(
                                  context,
                                  MaterialPageRoute(builder: (context) => Authenticate()),
                                );

                                *** As you can see above, here is where I call Authenticate() ***
                                ****** But by adding this extra step to reach the SignIn page, when I signin it doesn't redirect to the Home once signed in. It stays on the SignIn screen. If I hard refresh the app, the system is logged in **********

                                
                              }
                            )
                          )
                        ]
                      )
                    )
                  )
            ))]);
    }
  }

使用Navigate小部件进入SignIn页面后，登录后似乎无法进入Home屏幕成功。
身份验证工作正常，因为如果我强制刷新该应用程序，它将显示为登录用户的Home屏幕。

似乎onPress要进行身份验证，在Home和StartAuthButton之间进行选择的IF STATEMENT不会被触发。

我们非常感谢您的帮助。很抱歉使用长脚本。乔

Answer 1

感谢@Unbreachable建议您查看有关弹出和推送的文章。

我对d = dict.fromkeys(df.columns.difference(['type1','type2']), 'max') d['type3'] = 'first' d['val1'] = 'last' df = df.groupby(["type1","type2"], as_index=False, sort=False).agg(d) print (df) type1 type2 type3 val1 val2 val3 0 a b q 4 6 7 1 a c w 2 5 8 2 b c t 2 9 0和SignIn小部件进行了简单的更改。这两个小部件都提交了onPress按钮。

之前的代码：

Register

及之后：

onPressed: () async {
   if (_formKey.currentState.validate()) {
     setState(() => loading = true);
                                          
    dynamic result = await _auth.registerWithEmailAndPassword(email, password);

    if (result == null) {
      setState(() {
          error = 'Email or password are invalid.';
          loading = false;
      });
    }
  }
},

现在，加载工作正常，当消失时，我可以看到onPressed: () async { if (_formKey.currentState.validate()) { setState(() => loading = true); dynamic result = await _auth.registerWithEmailAndPassword(email, password); if (result == null) { setState(() { error = 'Email or password are invalid.'; loading = false; }); } else { Navigator.of(context).pop(); <-- here the change. loading = false; <-- here the change. } } },小部件。

通过电子邮件/密码进行验证时出现颤振问题

1 个答案: