RxDart CombineLatest emit no data - dart

Question

I'm doing small project with FLUTTER/DART and RXDART.
Here is part of the code:
class RegisterBloc with UserValidator {
final _username = BehaviorSubject<String>();
final _email = BehaviorSubject<String>();
final _password = BehaviorSubject<String>();
Function(String) get setUsername => _username.sink.add;
Stream<String> get username => _username.stream.transform(usernameValidatorTransformer);
Function(String) get setEmail => _email.sink.add;
Stream<String> get email => _email.stream.transform(emailValidatorTransformer);
Function(String) get setPassword => _password.sink.add;
Stream<String> get password => _password.stream.transform(passwordValidatorTransformer);
Stream<bool> get validForm => CombineLatestStream.combine3<String, String, String, bool>(_username.stream, _email.stream, _password.stream, (u, e, p) => true);
submit() async {
final form = RegisterForm(
username: _username.value,
email: _email.value,
password: _password.value
);
}
dispose() {
_username.close();
_email.close();
_password.close();
}
}
The Problem is validForm Stream emit null data and combiner never get called, even all streams already emit at least 1 value.
What worst, this only happen on Android (mine v.8.1.0), the codes work just as expected on iOS 11.
In case anyone wondering, i use StreamBuilder widget to update widget data.
Do i missing something here? any configuration need to be set prior or else.
Here my Development Environment:
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, v1.2.1, on Mac OS X 10.13.6 17G6030, locale en-ID)
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
[✓] iOS toolchain - develop for iOS devices (Xcode 10.1)
[✓] Android Studio (version 3.3)
[✓] Connected device (1 available)
RxDart: 0.21.0
Android Device: 8.1.0

Answer 1

I did a project like this and it's working correctly, everything in ur bloc class is ok, i guess the problem is in ur validator class, if u shared ur validation class maybe i could help u more,
Here my codes
Its the bloc class :
class Bloc with Validator {
final _emailController = BehaviorSubject<String>();
final _passwordController = BehaviorSubject<String>();
final _textController = BehaviorSubject<String>();
// add to stream
Function(String) get reciveText => _textController.sink.add;
Function(String) get changeEmail => _emailController.sink.add;
Function(String) get changePassword => _passwordController.sink.add;
// access to stream
Stream<String> get emailvalidation =>
_emailController.stream.transform(validateEmail);
Stream<String> get passwordvalidation =>
_passwordController.stream.transform(validatePassword);
Stream<bool> get submitValid =>
Rx.combineLatest2(emailvalidation, passwordvalidation, (a, b) => true);
Stream<String> get accesstext =>
_textController.stream.transform(validateText);
submit() {
final validemail = _emailController.value;
final validpass = _passwordController.value;
reciveText('user name : $validemail \n pass : $validpass ');
print('all valid');
}
And its validation codes :
final validateEmail = StreamTransformer<String, String>.fromHandlers(
handleData: (data, sink) {
if (data.contains('#') && data.contains('.')) {
sink.add(data);
} else {
sink.addError('Enter Valid emaill');
}
},
);
final validatePassword = StreamTransformer<String, String>.fromHandlers(
handleData: (data, sink) {
if (data.length > 3) {
sink.add(data);
} else {
sink.addError('Password is too short');
}
},
);
by the way u can see my codes that are working fine in my GitHub, maybe it help u to see what is going wrong in ur project.
https://github.com/Manticodes/flutter_loginscreen_blocpattern
I hope it help u to solve ur problem.