如何在Flutter中从Firebase获取当前用户ID

Question

我正在尝试-

final Future<FirebaseUser> user = auth.currentUser();

但是问题在于，不是通过“ userid”创建文档，而是通过以下名称创建文档：

Instance of 'Future<FirebaseUser>'

从字面上看，这是我现在的文档名称，但是我想专门使其成为用户名。

我该怎么办？

Answer 1

uid是FirebaseUser对象的属性。由于auth.currentUser（）返回一个future，因此必须等待以获取如下用户对象：

void inputData() async {
    final FirebaseUser user = await auth.currentUser();
    final uid = user.uid
    // here you write the codes to input the data into firestore
  }

Answer 2

如果您使用 Google 登录，您将获得此用户信息。

final FirebaseAuth firebaseAuth = FirebaseAuth.instance;
final GoogleSignIn _googleSignIn = new GoogleSignIn();
void initState(){
super.initState();
 firebaseAuth.onAuthStateChanged
        .firstWhere((user) => user != null)
        .then((user) {
      String user_Name = user.displayName;
      String image_Url = user.photoUrl;
      String email_Id = user.email;
      String user_Uuid = user.uid; // etc
      }
       // Give the navigation animations, etc, some time to finish
    new Future.delayed(new Duration(seconds: 2))
        .then((_) => signInWithGoogle());
        }

     Future<FirebaseUser> signInWithGoogle() async {
  // Attempt to get the currently authenticated user
  GoogleSignInAccount currentUser = _googleSignIn.currentUser;
  if (currentUser == null) {
    // Attempt to sign in without user interaction
    currentUser = await _googleSignIn.signInSilently();
  }
  if (currentUser == null) {
    // Force the user to interactively sign in
    currentUser = await _googleSignIn.signIn();
  }

  final GoogleSignInAuthentication googleAuth =
      await currentUser.authentication;

  // Authenticate with firebase
  final FirebaseUser user = await firebaseAuth.signInWithGoogle(
    idToken: googleAuth.idToken,
    accessToken: googleAuth.accessToken,
  );

  assert(user != null);
  assert(!user.isAnonymous);

  return user;
}

Answer 3

您需要等待异步操作完成。

final FirebaseUser user = await auth.currentUser();
final userid = user.uid;

或者您可以使用 then 样式语法：

final FirebaseUser user = auth.currentUser().then((FirebaseUser user) {
  final userid = user.uid;
  // rest of the code|  do stuff
});

Answer 4

final FirebaseAuth _auth = FirebaseAuth.instance;
getCurrentUser() async {
    final FirebaseUser user = await _auth.currentUser();
    final uid = user.uid;
    // Similarly we can get email as well
    //final uemail = user.email;
    print(uid);
    //print(uemail);
  }

调用函数 getCurrentUser 获取结果。例如，我使用了一个按钮：

RaisedButton(
              onPressed: getCurrentUser,
              child: Text('Details'),
            ),

Answer 5

更新（空安全）

要获取有关用户的 uid、电子邮件和其他信息，请检查用户是否已登录，然后从类中检索这些值User。

User? user = FirebaseAuth.instance.currentUser;

// Check if the user is signed in
if (user != null) {
  String uid = user.uid; // <-- User ID
  String? email = user.email; // <-- Their email
}