rxjs - 是否可以通过发出 Action 来启动/停止/恢复 redux-observable 史诗？

Question

这个问题可能是关于redux-observable或 rxjs或两者。

我正在寻找一种通过特定 Action 开始、停止或恢复史诗的方法。例如，当操作 {type: 'START'} 时，史诗(已经是史诗中间件的一部分)将处于事件状态。已收到，但在操作 {type: 'END'} 时将处于非事件状态收到。这可能吗？

Answer 1

您可以使用 switchMap 的组合和 filter这样做(假设所有 Action 包括开始/结束 Action 来自同一个来源)

如果开始/结束 Action 来自单独的源，那就更容易了，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运行情况。

// 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$);

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