Flutter Google 登录：重定向到主页或注册，而不是新用户的主页\注册页面

Question

我正在开发一个 Flutter 应用程序，用户可以使用他们的 Google 帐户登录。我已经实现了 Google 登录功能，但我遇到了导航流程和身份验证问题。

当新用户登录 Google 时，他们应该被引导至注册页面，可以在其中提供其他信息，例如联系电话、商店名称和地址。提供此信息后，应将其存储在 Firestore 中。 现在，下次当用户使用相同的 Google 帐户登录时，他应该被定向到主页，在本例中为 btmnavbar

但是，我无法实现这个目标。下面的代码确实在 Firestore 中注册了所有必需的详细信息，但下次当用户使用同一电子邮件登录时，它会再次导航到注册页面并询问信息 在注册页面中，详细信息应存储在登录页面中选择的同一电子邮件

登录页面 sinin 功能

class _LoginAppState extends State<LoginApp> {
  ScrollController scrollController = ScrollController();
  bool isHidden = true;
  bool isLoading = false;
  TextEditingController controllerEmail = TextEditingController();
  TextEditingController controllerPassword = TextEditingController();
  final GoogleSignIn googleSignIn = GoogleSignIn();
  TextEditingController resetPassController = TextEditingController();
  final auth = FirebaseAuth.instance;
  final GoogleSignIn _googleSignIn = GoogleSignIn();

/////////////////////////////////////////////////////////////
  //////////Function for Google SIGN IN/////////////////////
  ///////////////////////////////////////////////////

  Future<User?> signingoogle() async {
    try {
      // GoogleSignIn().signOut();
      final GoogleSignInAccount? googleaccount = await GoogleSignIn().signIn();
      
      if (googleaccount == null) {
        return null;
      }
       print('Creating Google Auth');
      final GoogleSignInAuthentication googleAuth =
          await googleaccount.authentication;
      final AuthCredential credential = GoogleAuthProvider.credential(
        accessToken: googleAuth.accessToken,
        idToken: googleAuth.idToken,
        
      );
 
      final UserCredential userCredential =
          await FirebaseAuth.instance.signInWithCredential(credential);
           
      final User? user = userCredential.user;
     
      if (user != null) {
        final CollectionReference users =
            FirebaseFirestore.instance.collection('users');
        final DocumentSnapshot emailDocument = await users.doc(user.uid).get();
        if (emailDocument.exists) {
          Navigator.push(
              context, MaterialPageRoute(builder: (context) => btmNavBar()));
        } else {
          await users.doc(user.uid).set({'email': user.email});
          final AuthCredential emailAuthCredential =
              EmailAuthProvider.credential(
                  email: user.email.toString(), password: 'google password');
          await userCredential.user!.linkWithCredential(emailAuthCredential);
        }
        Navigator.push(
            context, MaterialPageRoute(builder: (context) => SignUpGoogle()));
      }
      return user;
    } catch (e) {
      print('$e');
    }
    return null;
  }

这是我的注册页面功能

class _SignUpGoogleState extends State<SignUpGoogle> {
  TextEditingController contactController = TextEditingController();
  TextEditingController storeNameController = TextEditingController();
  TextEditingController addressController = TextEditingController();
  final formKey = GlobalKey<FormState>();
  final GoogleSignIn _googleSignIn = GoogleSignIn();
  final auth = FirebaseAuth.instance;
  final firestore = FirebaseFirestore.instance;
  User? currentUser = FirebaseAuth.instance.currentUser;

  Future<void> saveUserData(String userId, String email, String contact,
      String storeName, String address) async {
    try {
      // Save user data to Firestore
      await firestore.collection('users').doc(userId).set({
        'email': email,
        'contact': contact,
        'storeName': storeName,
        'address': address,
      });
    } catch (e) {
      print('Error saving user data: $e');
    }
  }

 SecondayBtn(
                  onPressed: () async {
                    var userContact = contactController.text.trim();
                    var storeName = storeNameController.text.trim();
                    var userAddress = addressController.text.trim();
                    if (formKey.currentState!.validate()) {
                      try {
                        final GoogleSignInAccount? googleSignInAccount =
                            await _googleSignIn.signIn();
                        if (googleSignInAccount != null) {
                          final GoogleSignInAuthentication
                              googleSignInAuthentication =
                              await googleSignInAccount.authentication;
                          final AuthCredential credential =
                              GoogleAuthProvider.credential(
                            accessToken: googleSignInAuthentication.accessToken,
                            idToken: googleSignInAuthentication.idToken,
                          );
                          final UserCredential userCredential =
                              await auth.signInWithCredential(credential);
                          final User? user = userCredential.user;

                          if (user != null) {
                            // Save additional user data to Firestore
                            await saveUserData(user.uid, user.email!,
                                userContact, storeName, userAddress);
                            Navigator.pushReplacement(
                              context,
                              MaterialPageRoute(
                                  builder: (context) => btmNavBar()),
                            );
                          }
                        }
                      } catch (e) {}
                    }
                  },
                  btntxt: 'Sign Up With Google',
                ),

当新用户登录 Google 时，他们应该被引导至注册页面，可以在其中提供其他信息，例如联系电话、商店名称和地址。提供此信息后，应将其存储在 Firestore 中。 现在，下次当用户使用相同的 Google 帐户登录时，他应该被定向到主页，在本例中为 btmnavbar

Answer 1

逻辑处理代码似乎存在问题，决定在

signingoogle()

方法内导航到何处。无论您正在处理什么，它始终会导航到 SignUpGoogle 页面。

if (user != null) {
  final CollectionReference users =
  FirebaseFirestore.instance.collection('users');
  final DocumentSnapshot emailDocument = await users.doc(user.uid).get();
  if (emailDocument.exists) {
    Navigator.push(
        context, MaterialPageRoute(builder: (context) => btmNavBar()));
  } else {
    await users.doc(user.uid).set({'email': user.email});
    final AuthCredential emailAuthCredential =
    EmailAuthProvider.credential(
        email: user.email.toString(), password: 'google password');
    await userCredential.user!.linkWithCredential(emailAuthCredential);
  }

  Navigator.push(
      context, MaterialPageRoute(builder: (context) => SignUpGoogle())); //<<< Here! This is outside of the if-else statement 
}