Accessing a stream inside a Nested StreamBuilder in Flutter - flutter

Question

I am having an issue calling a StreamBuilder inside another StreamBuilder which is located inside the onPressed field of RasedButton widget. Basically, I am trying to access a stream (after adding data to it) inside the inner StreamBuilder, but the execution does not call this part of the code:
Widget submitButton(BuildContext ctx, AccountBloc bloc){
return StreamBuilder(
stream: bloc.submitValid,
builder: (context, snapshot){
return SizedBox(
width: double.infinity,
height: 60,
child: RaisedButton(
color: HexColor("0072b1"),
child: Text("Sign in", style: TextStyle(
fontWeight: FontWeight.bold,
fontSize: 20,
color: Colors.white
),
),
onPressed:() {
if(snapshot.hasData){
bloc.loginUser();
// DEBUGGING
print(bloc.isAuthenticated.listen((val) { print("debug isAuthenticated: $val"); }));
StreamBuilder(
stream: bloc.isAuthenticated,
builder: (ctx, snapshotA){
print("here");
if(!snapshotA.hasData){
return Text("loading....");
}
print("***${snapshotA.data}****");
if(snapshotA.data == false){
return navSignUpScreen(ctx);
}else if (snapshotA.data == false){
print("here");
return navHomeScreen(ctx);
}
return navSignUpScreen(ctx);
}
);
}
},
),
);
}
);
}
The BLOC part is as follows:
final _isAuthenticated = BehaviorSubject<bool>();
Stream<bool> get isAuthenticated => _isAuthenticated.stream;
void loginUser() async {
var inMemory = InMemoryProvider();
inMemory.newInMemoryProvider();
UserModel userResult = await _repository.loginUser(_email.value, _password.value);
if(userResult.status == 200){
// save TOKEN
UserModel userModel = UserModel.fromJsonToModel(userResult.data);
bool res = await inMemory.store(userModel.id, userModel.token);
_isAuthenticated.sink.add(res);
}
_userLoginResponse.sink.add(userResult);
}
The navHomeScreen definition is as simple as this:
class HomeScreen extends StatefulWidget {
createState() {
return HomeState();
}
}
class HomeState extends State<HomeScreen> {
int _currentIndex = 0;
final List<Widget> _children = [
AllReportsScreen(), UserProfileScreen()
];
Widget build(context) {
return Scaffold(
body: _children[_currentIndex],
bottomNavigationBar: mainBottomNavigatorBar(),
);
}
Widget mainBottomNavigatorBar() {
return BottomNavigationBar(
type: BottomNavigationBarType.fixed,
onTap: onTabTapped,
currentIndex: _currentIndex,
items: [
BottomNavigationBarItem(
backgroundColor: Colors.black45,
icon: new Icon(Icons.note),
title: new Text('Reports', style: TextStyle(fontSize: 15.0)),
),
BottomNavigationBarItem(
backgroundColor: Colors.black45,
icon: new Icon(Icons.label_important),
title: new Text('Attention', style: TextStyle(fontSize: 15.0)),
),
BottomNavigationBarItem(
backgroundColor: Colors.black45,
icon: new Icon(Icons.person_pin),
title: new Text('Profile', style: TextStyle(fontSize: 15.0)),
),
],
);
}
void onTabTapped(int index) {
setState(() {
_currentIndex = index;
});
}
}

Answer 1

Using combineLatest from rxdart to combine two Streams isAuthenticated and submitValid into one Stream:
class LoginState {
final bool isAuthenticated;
final bool submitValid;
}
final state$ = Rx.combineLatest(
bloc.isAuthenticated,
bloc.submitValid,
(isAuth, valid) => LoginState(isAuth, valid),
);
StreamBuilder<LoginState>(
stream: state$,
builder: (context, snapshot) {
final state = snapshot.data;
if (state == null) return ...;
if (!state.submitValid) return ...;
if (state.isAuthenticated) return ...;
}
)