Flutter onPressed异步功能不等待来自手肘/存储库的等待功能

如何解决Flutter onPressed异步功能不等待来自手肘/存储库的等待功能

我有一个注册按钮，可将http请求发送到我的API。请求完成后，我想离开注册页面。使用Bloc模式，我向Bloc中添加了一个事件以导航至登录页面，但是注册页面在将事件添加至Bloc之前并不等待http请求完成。

注册按钮代码：-

class _SignUpButton extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocBuilder<SignUpCubit,SignUpState>(
      buildWhen: (previous,current) => previous.status != current.status,builder: (context,state) {
        return state.status.isSubmissionInProgress
            ? const CircularProgressIndicator()
            : IconButton(
                key: const Key('loginForm_continue_raisedButton'),onPressed: state.status.isValidated
                    ? () async {
                      await context.bloc<SignUpCubit>().signUpFormSubmitted();
                      context.bloc<AuthenticationBloc>().add(AuthenticationUserChanged(User.empty));
                    }
                    : () => print('invalid'),icon: Icon(Icons.keyboard_arrow_right),color: Colors.white,iconSize: 40,);
      },);
  }
}

注册权限：-

part 'signup_state.dart';

class SignUpCubit extends Cubit<SignUpState> {
  SignUpCubit(this._authenticationRepository)
      : assert(_authenticationRepository != null),super(const SignUpState());

  final AuthenticationRepository _authenticationRepository;

  //irrelevant code omitted

  Future<void> signUpFormSubmitted() async {
    if (!state.status.isValidated) return;
    emit(state.copyWith(status: FormzStatus.submissionInProgress));
    try {
      await _authenticationRepository.signUp(
          name: state.name,password: state.password.value,mobile: state.mobile.value,village: state.village,email: state.email.value,pincode: state.pincode);
      emit(state.copyWith(status: FormzStatus.submissionSuccess));
    } on Exception {
      emit(state.copyWith(status: FormzStatus.submissionFailure));
    }
  }
}

身份验证存储库：-

/// Thrown if during the sign up process if a failure occurs.
class SignUpFailure implements Exception {}

class AuthenticationRepository {
  /// {@macro authentication_repository}
  AuthenticationRepository({
    FirebaseAuth firebaseAuth,GoogleSignIn googleSignIn,})  : _firebaseAuth = firebaseAuth ?? FirebaseAuth.instance,_googleSignIn = googleSignIn ?? GoogleSignIn.standard();

  final FirebaseAuth _firebaseAuth;
  final GoogleSignIn _googleSignIn;

  /// Stream of [User] which will emit the current user when
  /// the authentication state changes.
  ///
  /// Emits [User.empty] if the user is not authenticated.
  Stream<User> get user {
    return _firebaseAuth.onAuthStateChanged.map((firebaseUser) {
      return firebaseUser == null ? User.empty : firebaseUser.toUser;
    });
  }

  //irrelevant code omitted

  Future<void> signUp(
      {@required String name,@required String password,@required String mobile,@required String village,@required String pincode,@required String email}) async {
    assert(
        name != null && mobile != null && village != null && pincode != null);
    try {
      if (email != '' && password != '') {
        await _firebaseAuth.createUserWithEmailAndPassword(
            email: email,password: password);
      }
      final params = {
        'name': name,'phone': mobile,'village': village + '_' + pincode,'api': 't','login': 'NA'
      };
      Response res = await Dio().get(
          "https://us-central1-greensat-9087a.cloudfunctions.net/addUser",queryParameters: params);
      print(res.data);
    } on Exception {
      throw SignUpFailure();
    }
  }  

}

身份验证集团：-

class AuthenticationBloc
    extends Bloc<AuthenticationEvent,AuthenticationState> {
  AuthenticationBloc({
    @required AuthenticationRepository authenticationRepository,})  : assert(authenticationRepository != null),_authenticationRepository = authenticationRepository,super(const AuthenticationState.unknown()) {
    _userSubscription = _authenticationRepository.user.listen(
      (user) => add(AuthenticationUserChanged(user)),);
  }

  final AuthenticationRepository _authenticationRepository;
  StreamSubscription<User> _userSubscription;

  @override
  Stream<AuthenticationState> mapEventToState(
    AuthenticationEvent event,) async* {
    if (event is AuthenticationUserChanged) {
      yield _mapAuthenticationUserChangedToState(event);
    } else if (event is AuthenticationLogoutRequested) {
      unawaited(_authenticationRepository.logOut());
    } else if (event is AuthenticationOTPRequested) {
      yield _mapAuthenticationUserOTPRequested(event);
    } else if (event is AuthenticationSignupStarted) {
      yield _mapAuthenticationUserSignupStarted(event);
    }
  }

  @override
  Future<void> close() {
    _userSubscription?.cancel();
    return super.close();
  }

  AuthenticationState _mapAuthenticationUserChangedToState(
    AuthenticationUserChanged event,) {
    print('user changed state');
    print(event.user);
    return event.user != User.empty
        ? AuthenticationState.authenticated(event.user)
        : const AuthenticationState.unauthenticated();
  }

  AuthenticationState _mapAuthenticationUserOTPRequested(
    AuthenticationOTPRequested event,) {
    return const AuthenticationState.unauthenticatedOTP();
  }

  AuthenticationState _mapAuthenticationUserSignupStarted(
    AuthenticationSignupStarted event,) {
    return const AuthenticationState.signupStarted();
  }
}

解决方法

你不能在 cubit 发射器函数中使用 async

错误：⛔️

void increment() async => emit(state+1)

正确：✅

void increment() => emit(state+1)