How to update screen A when navigating back from screen B with bloc flutter - flutter

Question

I have a screen(A) which use 'AccountFetched' state to load list of data from database:
return BlocProvider<AccountBloc>(
create: (context) {
return _accountBloc..add(FetchAccountEvent());
},
child: BlocBuilder<AccountBloc, AccountState>(
builder: (context, state) {
if (state is AccountFetched) {
accounts = state.accounts;
}
And in my second screen(B) I call AddAccountEvent to add data to database and navigate back to screen(A) which is the parent screen.
onPressed: () {
BlocProvider.of<AccountBloc>(context)
..add(AddAccountEvent(account: account));
Navigator.of(context).pop();
}
But when I navigate back to screen A, the list of data is not updated.
Should I refresh the screen(A) manually or how can I update the state of bloc?
This is my bloc class:
class AccountBloc extends Bloc<AccountEvent, AccountState> {
AccountBloc() : super(AccountInitial());
#override
Stream<AccountState> mapEventToState(AccountEvent event) async* {
if (event is FetchAccountEvent) yield* _fetchAccountEvent(event, state);
if (event is AddAccountEvent) yield* _addAccountEvent(event, state);
}
Stream<AccountState> _fetchAccountEvent(
FetchAccountEvent event, AccountState state) async* {
yield FetchingAccount();
final dbAccount = await DBAccountRepository.instance;
List<Account> accounts = await dbAccount.accounts();
yield AccountFetched(accounts: accounts);
}
Stream<AccountState> _addAccountEvent(
AddAccountEvent event, AccountState state) async* {
yield AddingAccount();
final dbAccount = await DBAccountRepository.instance;
final insertedId = await dbAccount.insertAccount(event.account);
yield AccountAdded(insertedId: insertedId);
}
}

Answer 1

I was experiencing the same problem, the solution I found was to make screen A wait for screen B to close, and after that trigger the data reload event for screen A.
onTap: () async {
await Navigator.of(context).push(ScreenB());
_bloc.add(RequestDataEvent());
}
So it will only execute the event after screen B is closed

Answer 2

well, you are creating a new bloc on page A. try to move BlocProvider 1 level up. so when the build function of page A calls, doesn't create a new bloc.

Answer 3

You should have a BlocListener in screen A listening for AccountState , with a if ( state is AccountFetched ) {} statement and perform your data update in a setState() . Depending on how long it takes to display screen A you might have the AccountFetched state been yielded before so screen A won't see it, in this case you could delay by 250 milliseconds yielding it in your _addAccount method either with a Timer or a Future.delayed.
Hope it helped.