flutter: how to use 'await for' to wait for other BLoC event to finish

user_13648205 0
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on screen init, I am loading my data via an externalData_bloc. On the same screen I am also rendering another widget controlled with internalData_bloc for user input which depends on the number of imported records (how many rows are needed). Of course, the rendering is faster than the data load, so I get null rows needed.

I found this nice question & answer, however, I do not get it to work. The solution says

Future loginProcess() async {
  await for (var result in _userBloc.state) {
    if (result.status == Status.finished) {
      return;
    }
  }
}

I am within my repository. In here, I am also storing the external data in a variable. So within the repository class I have my function to get the number of records (properties are stored in the repository, and I want to return its length).

  Future<int> getNoOfProperties(int problem)  async {
    LogicGraphsPStmntBloc bloc = LogicGraphsPStmntBloc();
    Future propertiesLoad() async {
      await for (var s in bloc) {
        if (s == LogicGraphsPStmntLoadSuccess) {
          return;
        }
      }
    }
    propertiesLoad();
    return properties.length;
  }

But no matter what I try to put in for await for (var result in XXXX) or if (s.YYY == ZZZ), it doesn't work. My understanding is, XXXX needs to be a stream which is why I used bloc = LogicGraphsPStmntBloc(). But I guess this creates another instance than the one used in my widgets. LogicGraphsPStmntBloc doesn't work either, nor do states. bloc at least doesn't throw an error already in the editor, but besides the instance issue, the if statement throws an error, where in cubit.dart StreamSubscription<State> listen(... is called with cancelOnError . Anyone having some enlightenment?

async-await bloc flutter state
1 Answers

Bloc uses Stream and has a continuous flow of data. You might want to listen for changes in data instead of a finished task. Using a StreamBuilder is one way of doing this.

StreamBuilder<User>(
  stream: bloc.userState, // Stream from bloc
  builder: (context, AsyncSnapshot<State> snapshot) {
    if (snapshot.hasData) {
      // check if auth status is finished
    }
  }
)
user_24978590
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