Question

此问题可能与redux-observable或rxjs或两者有关。

我正在寻找一种通过特定动作来启动，停止或恢复史诗的方法。例如，史诗（已经是史诗middelware的一部分）将在收到操作{type: 'START'}时处于活动状态，但在收到操作{type: 'END'}时将处于非活动状态。这可能吗？

Answer 1

您可以使用switchMap和filter的组合来执行此操作（假设所有操作包括开始/结束操作来自同一来源）

如果您的开始/结束操作来自单独的来源，则更容易，那么您可以跳过分离源流的步骤。

运行下面的代码示例以查看它的实际效果。

// this would be your source
const actions$ = new Rx.Subject();

// in this example controllActions and dataActions are derived from the same stream,
// if you have the chance to use 2 seperate channels from the start, do that
const controllActions$ = actions$
  .filter(action => action.type === "END" || action.type === "START");
const dataActions$ = actions$
  .filter(action => action.type !== "END" && action.type !== "START");

const epic$ = controllActions$
  .switchMap(action => {
    if (action.type === "END") {
      console.info("Pausing stream");
      return Rx.Observable.never();
    } else {
      console.info("Starting/Resuming stream");
      return dataActions$;
    }
  });
epic$.subscribe(console.log);

// simulating some action emissions, the code below is _not_ relevant for the actual implementation
Rx.Observable.from([
  "Some data, that will not be emitted...",
  {type: "START"},
  "Some data, that _will_ be emitted...",
  "Some more data, that _will_ be emitted...",
  {type: "END"},
  "Some data, that will not be emitted...",
  "Some data, that will not be emitted...",
  {type: "START"},
  "Some data, that _will_ be emitted...",
  "Some more data, that _will_ be emitted..."
])
  .concatMap(d => Rx.Observable.of(d).delay(400))
  .subscribe(actions$);

<script src="https://unpkg.com/rxjs/bundles/Rx.min.js"></script>

是否可以通过发出动作来启动/停止/恢复redux-observable史诗？

1 个答案: