rxjs - Redux Observable 史诗中的 IF

Question

我有一个史诗，可以捕获每次获取状态的调度(只是来自状态的项目，例如 state.process:{ status: failed, success, inWork}，而不是像 200、500 等这样的请求状态)。 当状态==成功时(通过从状态获取状态)我需要调度另一个操作，例如SET_STATUS_SUCCESS

const getStatus = (action, state) =>
    action.pipe(
        ofType(GET_STATUS),
        withLatestFrom(state),
        mergeMap(([action, state]) => {
            const { status } = state.api.process; //here is what i need, there is no problem with status.
            if (status === "success") {
              return mapTo(SET_STATUS_SUCCESS) //got nothing and error.
}
        })
    );

现在我收到错误:

Uncaught TypeError: You provided 'function (source) { return source.lift(new MapToOperator(value)); }' where a stream was expected. You can provide an Observable, Promise, Array, or Iterable. at subscribeTo (subscribeTo.js:41)

我该怎么办？我尝试只返回 setStatusSuccess 操作，但它也不起作用。

Answer 1

您需要从传递给 mergeMap 的函数返回一个可观察值。试试这个:

const getStatus = (action, state) =>
  action.pipe(
    ofType(GET_STATUS),
    withLatestFrom(state),
    mergeMap(([action, state]) => {
      const { status } = state.api.process;

      if (status === 'success') {
        return of({ type: SET_STATUS_SUCCESS });
      } else {
        return EMPTY;
      }
    }),
  );

of和 EMPTY是从 rxjs 进口的.