Firebase 身份验证期望未被 catch 捕获

Question

使用错误的凭据登录时，会按预期抛出

Exception

。然而，

catch block

未能赶上

Exception

，导致崩溃。

发生异常。 FirebaseAuthException （[firebase_auth/invalid-credential] 提供的身份验证凭据是 不正确、格式错误或已过期。）

void signInWithEmail(String email, String password) async {
  state = state.copyWith(isLoading: true);
  try {
    UserCredential result = await _auth.signInWithEmailAndPassword(email: email.trim(), password: password.trim());
    state = state.copyWith(user: await _createMyUserFromFirebaseUser(result.user!), isLoading: false);
  } on FirebaseAuthException catch (e) {
    state = state.copyWith(isLoading: false, error: e.toString());
  } on PlatformException catch (_) {} catch (_) {}
}

我发现其他人提到过这个问题，但从未找到解决方案。正如你所看到的，我尝试指定要捕获的异常，但不知何故它从未被捕获。

Answer 1

我创建了一个简化的示例来展示可能正在发生的事情：

typedef State = ({String userName, bool isLoading, String error});

State state = (userName: 'not set', isLoading: true, error: 'nothing');

void signInWithEmail({
  required String email,
  required String password,
  Function? errorCallback,
}) async {
  if (errorCallback == null) {
    final userName = await Future.delayed(Duration.zero, () => 'Nick2001');
    state = (userName: userName, isLoading: false, error: 'nothing');
  } else {
    throw errorCallback();
  }
}

void main() async {
  try {
    signInWithEmail(
      email: '[email protected]',
      password: '1234',
      errorCallback: () => 'User not registered.',
    );
    print(state);
  } catch (e) {
    print('Caught error in main:');
    print('  $e');
  }
}

即使设置了 catch 块来捕获每个可能的异常，该程序也会生成以下控制台输出。

$ dart main.dart
State: (error: nothing, isLoading: true, userName: not set)
Unhandled exception:
Exception: User not registered.
#0      signInWithEmail (file:///work/main.dart:14:5)
#1      main (file:///work/main.dart:20:5)
#2      _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:297:19)
#3      _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)

---

现在我们更改函数

signInWithEmail

的签名以返回

Future<void>

并在 main 中等待该函数：

Future<void> signInWithEmail({
  required String email,
  required String password,
  Function? errorCallback,
}) async {
  if (errorCallback == null) {
    final userName = await Future.delayed(Duration.zero, () => 'Nick2001');
    state = (userName: userName, isLoading: false, error: 'nothing');
  } else {
    throw errorCallback();
  }
}

void main() async {
  try {
    await signInWithEmail(
      email: '[email protected]',
      password: '1234',
      errorCallback: () => Exception('User not registered.'),
    );
    print('State: $state');
  } catch (e) {
    print('Caught error in main:');
    print('  $e');
  }
}

运行该程序会产生预期的输出：

Caught error in main:
  Exception: User not registered.

有关详细说明，请参阅处理标记为异步的 void Dart 函数中的错误。