在使用flutter_bloc库调度事件之前，请等待一些结果 [英] Awaiting some results before dispatching an event with flutter_bloc library

问题描述

我正在尝试创建一个BLOC，该BLOC依赖于其他两个基于时间的集团和一个基于非时间的集团.我所说的基于时间的意思是，例如，他们正在连接远程服务器，因此需要时间.就是这样工作的:

I am trying to create a BLOC which depends on two other time based bloc and a non-time based bloc. What i mean with time based is, for example they are connecting a remote server so it takes time. It's working just like this:

登录(这当然需要一些时间)

Login (It's of course taking some time)

如果登录成功

执行另一个过程(这也需要时间.它会返回未来.)

Do another process (This is something takes time also. It returns a future.)

登录并完成另一个过程后，让页面知道它.

After login and another process finishes, let the page know it.

我的BLOC取决于以下三个:

My BLOC depends on these three:

final UserBloc _userBloc;
final AnotherBloc _anotherBloc;
final FinishBloc _finishBloc;

在状态方法的map事件中，我应该调度相关事件.但是，我等不及他们是否完成.

Inside the map event to state method I should dispatch relevant events. However i cannot await if they are finished.

_userBloc.dispatch(
  Login(),
);

_anotherBloc.dispatch(
  AnotherProcess(),
);

//LetThePageKnowIt should work after login and another process
_finishBloc.dispatch(
  LetThePageKnowIt(),
);

是否有一种干净的方法可以在派遣某些东西之前等待其他人?

Is there a clean way to await some others before dispatching something?

正确地知道我使用了一种我不喜欢的方式.在我连接其他集团的主要集团的状态下，我有傻瓜.

Right know I use a way that i don't like. In the main bloc's state which i connect other blocs in it, I have bools.

class CombinerState {
  bool isLoginFinished = false;
  bool isAnotherProcessFinished = false;

我在主块的构造函数中侦听时间相关的块状态.当他们说我完成了"时，我只是将布尔值标记为"true".

I am listening the time dependent blocs' states in constructor of main bloc. When they yield "i am finished" I just mark the bools "true".

MainBloc(
  this._userBloc,
  this._anotherBloc,
  this._pageBloc,
); {
  _userBloc.state.listen(
    (state) {
      if (state.status == Status.finished) {
        dispatch(FinishLogin());
      }
    },
  );

  _anotherBloc.state.listen(
    (state) {
      if (state.status == AnotherStatus.finished) {
        dispatch(FinishAnotherProcess());
      }
    },
  );
}

，然后在将bool设置为true之后，为main bloc调度另一个事件，以检查所有bool是否都是true.

and I dispatch another event for main bloc to check if all the bools are true after setting a bool to true.

else if (event is FinishAnotherProcess) {
  newState.isAnotherProcessFinished = true;

  yield newState;

  dispatch(CheckIfReady());
}

如果布尔值是正确的，我将调度LetThePageKnowIt()

If the bools are true, i dispatch LetThePageKnowIt()

else if (event is CheckIfReady) {
  if (currentState.isAnotherProcessFinished == true &&
      currentState.isLoginFinished == true) {
    _pageBloc.dispatch(LetThePageKnowIt());
  }
}

我对这段代码不满意.我正在寻找一种方法来等待其他BLOC发送完成"状态.之后，我想调度我的LetThePageKnowIt()

I am not satisfied with this code. I am looking a way to await other BLOCs send a state with "finished". After that I want to dispatch my LetThePageKnowIt()

推荐答案

@pskink的建议解决了我的问题.

@pskink 's suggestion solved my problem.

我创建了两个返回未来的方法.在他们里面，我只是在等待我的流.这是登录流的示例.

I have created two methods which return a future. Inside of them, I just await for my streams. Here is the example of login stream.

在要声明的地图事件中，在分派之后，我等待一个异步方法.

In map event to state, after the dispatches, I await an async method.

_userBloc.dispatch(
  Login(),
);

_anotherBloc.dispatch(
  AnotherProcess(),
);

await loginProcess();
await otherProcess();

_finishBloc.dispatch(
  LetThePageKnowIt(),
);

在方法中，我只是等待userbloc完成其工作并产生收益.然后返回.

Inside the method I just await for userbloc to finish its job and yields about it. Then return.

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

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