Flutter 颤振:子块正在初始化,但数据尚未存储在共享_首选项中
我用于我的应用程序jwt身份验证。我有一个带有bloc模式的主页,它选择页面将其加载到屏幕上(LoginScreen或AppScreen)。LoginScreen有自己的集团模式,也有AppScreen。 当我写login和password并单击login时,LoginEvent被调度,它向web服务发送请求,并使用jwt令牌获得响应,jwt令牌将存储在共享首选项中,但同时AppScreen使用他的bloc呈现,此时AppScreen的bloc正在发送数据请求(需要jwt令牌),但返回null,因为jwt令牌尚未存储。我发现一种工作方式并不优雅,我也可以使用延迟,但这不是正确的方式 AppScreen的解决方法:Flutter 颤振:子块正在初始化,但数据尚未存储在共享_首选项中,flutter,dart,bloc,flutter-navigation,Flutter,Dart,Bloc,Flutter Navigation,我用于我的应用程序jwt身份验证。我有一个带有bloc模式的主页,它选择页面将其加载到屏幕上(LoginScreen或AppScreen)。LoginScreen有自己的集团模式,也有AppScreen。 当我写login和password并单击login时,LoginEvent被调度,它向web服务发送请求,并使用jwt令牌获得响应,jwt令牌将存储在共享首选项中,但同时AppScreen使用他的bloc呈现,此时AppScreen的bloc正在发送数据请求(需要jwt令牌),但返回null,
@override
void initState() {
super.initState();
_bloc = BottomNavigationBloc(workoutTypeRepository: WorkoutTypeRepository());
_bloc.add(AppScreenLunched());
_bloc.add(AppScreenLunched());
}
class AppScreen extends StatefulWidget {
@override
_AppScreenState createState() => _AppScreenState();
}
class _AppScreenState extends State<AppScreen> {
BottomNavigationBloc _bloc;
@override
void initState() {
super.initState();
_bloc = BottomNavigationBloc(workoutTypeRepository: WorkoutTypeRepository());
_bloc.add(AppScreenLunched());
_bloc.add(AppScreenLunched());
}
@override
void dispose() {
super.dispose();
_bloc.close();
}
@override
Widget build(BuildContext context) {
return BlocProvider<BottomNavigationBloc>(
create: (_) => _bloc,
child: BlocBuilder(
bloc: _bloc,
builder: (BuildContext context, BottomNavigationState state) {
return Scaffold(
appBar: AppBar(
title: Text('TEST'),
),
body: _blocBuilder(context, state),
bottomNavigationBar: BottomActionBar(),
);
},
),
);
}
Widget _blocBuilder(BuildContext context, BottomNavigationState state) {
if (state is PageLoading) {
return Center(child: CircularProgressIndicator());
} else if (state is HomePageLoaded) {
return HomePage(workoutTypes: state.workoutTypes);
} else if (state is SearchPageLoaded) {
return Center(child: Text("SearchPage"));
// return SearchPage();
} else if (state is WorkoutPageLoaded) {
// return Center(child: Text("WorkoutPage"));
return WorkoutPage();
} else if (state is FavoritePageLoaded) {
return Center(child: Text("FavoritePage"));
// return SearchPage();
} else if (state is ProfilePageLoaded) {
return Center(child: Text("ProfilePage"));
// return ProfilePage();
}
return Container();
}
}
如果我离开\u bloc.add(appscreenlunted())代码>数据无法加载到主页,因为它从web服务接收空值
如果我离开
_bloc.add(AppScreenLunched());
_bloc.add(AppScreenLunched());
首先,添加数据为空
通过第二次add
我最终得到了数据,这些数据随bloc一起提供到主页上
有什么办法吗
开始屏幕:
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
AuthBloc _authBloc;
LoginRepository _loginRepository;
@override
void initState() {
super.initState();
_loginRepository = LoginRepository();
_authBloc = AuthBloc(loginRepository: _loginRepository);
_authBloc.add(AppStarted());
}
@override
void dispose() {
super.dispose();
_authBloc.close();
}
@override
Widget build(BuildContext context) {
return BlocProvider<AuthBloc>(
create: (_) => _authBloc,
child: MaterialApp(
title: 'TEST',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: BlocBuilder(
bloc: _authBloc,
builder: (BuildContext context, AuthState state) {
if (state is AuthUninitialized) {
return LoginPage(loginRepository: _loginRepository);
} else if (state is AuthAuthenticated) {
return AppScreen();
} else if (state is AuthUnauthenticated) {
return LoginPage(loginRepository: _loginRepository);
} else if (state is AuthLoading) {
return LoadingIndicator();
}
return LoginPage(loginRepository: _loginRepository);
}
)
)
);
}
}
类MyApp扩展StatefulWidget{
@凌驾
_MyAppState createState()=>\u MyAppState();
}
类MyAppState扩展了状态{
AuthBloc\u AuthBloc;
LoginRepository\u LoginRepository;
@凌驾
void initState(){
super.initState();
_loginRepository=loginRepository();
_authBloc=authBloc(loginRepository:_loginRepository);
_add(AppStarted());
}
@凌驾
无效处置(){
super.dispose();
_authBloc.close();
}
@凌驾
小部件构建(构建上下文){
返回BlocProvider(
创建:()=>authBloc,
孩子:MaterialApp(
标题:"测试",,
主题:主题数据(
主样本:颜色。蓝色,
),
主页:BlocBuilder(
集团:_authBloc,
生成器:(BuildContext上下文,AuthState){
如果(状态未初始化){
返回登录页面(loginRepository:\u loginRepository);
}else if(状态已通过身份验证){
返回AppScreen();
}else if(状态为未经身份验证){
返回登录页面(loginRepository:\u loginRepository);
}else if(状态为AuthLoading){
返回LoadingIndicator();
}
返回登录页面(loginRepository:\u loginRepository);
}
)
)
);
}
}
登录筛选(部分):
classloginform扩展StatefulWidget{
@凌驾
_LoginFormState createState()=>\u LoginFormState();
}
类_LoginFormState扩展状态{
final _emailController=TextEditingController();
final _passwordController=TextEditingController();
final registerRepository=registerRepository();
LoginBloc _LoginBloc;
@凌驾
void initState(){
super.initState();
_loginBloc=BlocProvider.of(上下文);
}
@凌驾
无效处置(){
super.dispose();
_loginBloc.close();
}
@凌驾
小部件构建(构建上下文){
_onLoginButtonPressed(){
_loginBloc.add(LoginButtonPressed(
电子邮件:_emailController.text,
密码:_passwordController.text,
));
}
应用屏幕:
@override
void initState() {
super.initState();
_bloc = BottomNavigationBloc(workoutTypeRepository: WorkoutTypeRepository());
_bloc.add(AppScreenLunched());
_bloc.add(AppScreenLunched());
}
class AppScreen extends StatefulWidget {
@override
_AppScreenState createState() => _AppScreenState();
}
class _AppScreenState extends State<AppScreen> {
BottomNavigationBloc _bloc;
@override
void initState() {
super.initState();
_bloc = BottomNavigationBloc(workoutTypeRepository: WorkoutTypeRepository());
_bloc.add(AppScreenLunched());
_bloc.add(AppScreenLunched());
}
@override
void dispose() {
super.dispose();
_bloc.close();
}
@override
Widget build(BuildContext context) {
return BlocProvider<BottomNavigationBloc>(
create: (_) => _bloc,
child: BlocBuilder(
bloc: _bloc,
builder: (BuildContext context, BottomNavigationState state) {
return Scaffold(
appBar: AppBar(
title: Text('TEST'),
),
body: _blocBuilder(context, state),
bottomNavigationBar: BottomActionBar(),
);
},
),
);
}
Widget _blocBuilder(BuildContext context, BottomNavigationState state) {
if (state is PageLoading) {
return Center(child: CircularProgressIndicator());
} else if (state is HomePageLoaded) {
return HomePage(workoutTypes: state.workoutTypes);
} else if (state is SearchPageLoaded) {
return Center(child: Text("SearchPage"));
// return SearchPage();
} else if (state is WorkoutPageLoaded) {
// return Center(child: Text("WorkoutPage"));
return WorkoutPage();
} else if (state is FavoritePageLoaded) {
return Center(child: Text("FavoritePage"));
// return SearchPage();
} else if (state is ProfilePageLoaded) {
return Center(child: Text("ProfilePage"));
// return ProfilePage();
}
return Container();
}
}
class AppScreen扩展StatefulWidget{
@凌驾
_AppScreenState createState()=>\u AppScreenState();
}
类_AppScreenState扩展状态{
底部导航集团(bloc);;
@凌驾
void initState(){
super.initState();
_bloc=BottomNavigationBloc(workoutTypeRepository:workoutTypeRepository());
_bloc.add(appscreenlunted());
_bloc.add(appscreenlunted());
}
@凌驾
无效处置(){
super.dispose();
_bloc.close();
}
@凌驾
小部件构建(构建上下文){
返回BlocProvider(
创建:(),
孩子:BlocBuilder(
集团:集团,
生成器:(BuildContext上下文,底部导航状态){
返回脚手架(
appBar:appBar(
标题:文本(“测试”),
),
正文:_blocBuilder(上下文、状态),
bottomNavigationBar:BottomActionBar(),
);
},
),
);
}
小部件\u blocBuilder(构建上下文上下文,底部导航状态){
如果(状态为页面加载){
返回中心(子项:CircularProgressIndicator());
}else if(状态为HomePageLoaded){
返回主页(workoutTypes:state.workoutTypes);
}else if(状态为SearchPageLoaded){
返回中心(子:文本(“搜索页面”);
//返回SearchPage();
}else if(状态为WorkoutPageLoaded){
//返回中心(子项:文本(“WorkoutPage”);
返回WorkoutPage();
}else if(状态为FavoritePageLoaded){
返回中心(子项:文本(“FavoritePage”);
//返回SearchPage();
}else if(状态为ProfilePageLoaded){
返回中心(子:文本(“ProfilePage”);
//返回ProfilePage();
}
返回容器();
}
}
AuthBloc:
class AuthBloc extends Bloc<AuthEvent, AuthState> {
final LoginRepository loginRepository;
AuthBloc({@required this.loginRepository}) : assert(loginRepository != null);
@override
AuthState get initialState => AuthUninitialized();
@override
Stream<AuthState> mapEventToState(
AuthEvent event,
) async* {
if (event is AppStarted) {
final bool hasToken = await loginRepository.hasToken();
if (hasToken) {
yield AuthAuthenticated();
} else {
yield AuthUnauthenticated();
}
}
if (event is LoggedIn) {
final bool hasToken = await loginRepository.hasToken();
if (hasToken) {
yield AuthAuthenticated();
} else {
yield AuthUnauthenticated();
}
}
if (event is LoggedOut) {
yield AuthLoading();
await loginRepository.deleteToken();
yield AuthUnauthenticated();
}
}
}
class AuthBloc extends Bloc<AuthEvent, AuthState> {
final LoginRepository loginRepository;
AuthBloc({@required this.loginRepository}) : assert(loginRepository != null);
@override
AuthState get initialState => AuthUninitialized();
@override
Stream<AuthState> mapEventToState(
AuthEvent event,
) async* {
if (event is AppStarted) {
final bool hasToken = await loginRepository.hasToken();
if (hasToken) {
yield AuthAuthenticated();
} else {
yield AuthUnauthenticated();
}
}
if (event is LoggedIn) {
final bool hasToken = await loginRepository.hasToken();
if (hasToken) {
yield AuthAuthenticated();
} else {
yield AuthUnauthenticated();
}
}
if (event is LoggedOut) {
yield AuthLoading();
await loginRepository.deleteToken();
yield AuthUnauthenticated();
}
}
}
class AuthBloc扩展了Bloc{
最终登录回复登录回复;
AuthBloc({@required this.loginRepository}):断言(loginRepository!=null);
@凌驾
AuthState get initialState=>AuthUninitialized();
@凌驾
流映射事件状态(
AuthEvent事件,
)异步*{
如果(事件已启动){
final bool hasToken=等待登录repository.hasToken();
如果(hasToken){
屈服强度();
}否则{
生成未经身份验证的();
}
}
if(事件为LoggedIn){
final bool hasToken=等待登录repository.hasToken();
如果(hasToken){
屈服强度();
}否则{
生成未经身份验证的();
}
}
如果(事件为LoggedOut){
屈服载荷();
wait loginRepository.deletetetok
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
AuthBloc _authBloc;
LoginRepository _loginRepository;
@override
void initState() {
super.initState();
_loginRepository = LoginRepository();
_authBloc = AuthBloc(loginRepository: _loginRepository);
_authBloc.add(AppStarted());
}
@override
void dispose() {
super.dispose();
_authBloc.close();
}
@override
Widget build(BuildContext context) {
return BlocProvider<AuthBloc>(
create: (context) => _authBloc,
child: MaterialApp(
title: 'TEST',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: BlocBuilder(
bloc: _authBloc,
builder: (BuildContext context, AuthState state) {
if (state is AuthUninitialized) {
return LoadingIndicator();
// return LoginPage(loginRepository: _loginRepository);
} else if (state is AuthAuthenticated) {
return AppScreen();
} else if (state is AuthUnauthenticated) {
return LoginPage(loginRepository: _loginRepository);
} else if (state is AuthLoading) {
return LoadingIndicator();
}
return LoginPage(loginRepository: _loginRepository);
}
)
)
);
}
}
class LoginPage extends StatelessWidget {
final LoginRepository loginRepository;
LoginPage({
Key key,
@required this.loginRepository
}) : assert(loginRepository != null), super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
body: BlocProvider(
create: (context) {
return LoginBloc(
loginRepository: loginRepository,
authBloc: BlocProvider.of<AuthBloc>(context)
);
},
child: Stack(
children: <Widget>[
new Container(
decoration: BoxDecoration(
image: backgroundImage
)
),
new Center(
child: SingleChildScrollView(
child: Column(
children: <Widget>[
LoginForm()
]
),
),
)
],
),
)
);
}
}
class AuthBloc extends Bloc<AuthEvent, AuthState> {
final LoginRepository loginRepository;
AuthBloc({@required this.loginRepository}) : assert(loginRepository != null);
@override
AuthState get initialState => AuthUninitialized();
@override
Stream<AuthState> mapEventToState(
AuthEvent event,
) async* {
if (event is AppStarted) {
final bool hasToken = await loginRepository.hasToken();
if (hasToken) {
yield AuthAuthenticated();
} else {
yield AuthUnauthenticated();
}
}
if (event is LoggedIn) {
final bool hasToken = await loginRepository.hasToken();
if (hasToken) {
yield AuthAuthenticated();
} else {
yield AuthUnauthenticated();
}
}
if (event is LoggedOut) {
yield AuthLoading();
await loginRepository.deleteToken();
yield AuthUnauthenticated();
}
}
}
class LoginBloc extends Bloc<LoginEvent, LoginState> {
final LoginRepository loginRepository;
final AuthBloc authBloc;
LoginBloc({
@required this.loginRepository,
@required this.authBloc,
}) : assert(loginRepository != null),
assert(authBloc != null);
LoginState get initialState => LoginInitial();
@override
Stream<LoginState> mapEventToState(LoginEvent event) async* {
if (event is LoginButtonPressed) {
yield LoginLoading();
try {
await loginRepository.authenticate(
email: event.email,
password: event.password,
);
authBloc.add(LoggedIn());
yield LoginInitial();
} catch (error) {
yield LoginFailure(error: error.toString());
}
}
}
}
class LoginRepository {
LoginProvider _loginProvider;
LoginRepository({LoginProvider loginProvider}) {
_loginProvider = loginProvider ?? LoginProvider();
}
Future<String> authenticate({String email, String password}) async {
if (email == null || password == null) {
return "Nie podanu loginu lub hasła";
}
var loginData =
await _loginProvider.login(email: email, password: password);
var token = AuthToken.fromJson(loginData);
return token.accessToken;
}
Future<bool> hasToken() async {
String token = await LocalStorage.get(Constant.ACCESS_TOKEN);
if (token != null) {
return true;
}
return false;
}
Future<void> persistToken(String token) async {
if (token != null) {
await LocalStorage.save(Constant.ACCESS_TOKEN, "${Constant.TOKEN_TYPE_BEARER} $token");
}
}
Future<void> deleteToken() async {
await LocalStorage.remove(Constant.ACCESS_TOKEN);
}
}
class LocalStorage {
static save(String key, String value) async {
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setString(key, value);
}
static Future<String> get(String key) async {
SharedPreferences prefs = await SharedPreferences.getInstance();
return prefs.get(key);
}
static remove(String key) async {
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.remove(key);
}
static removeAll() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
var keys = prefs.getKeys();
keys.map((key) {
remove(key);
});
}
}