Notify from inner flatMap

问题

Here a quite complex sample:

Main:

this.runInstructionAndGetResult().subscribe({
      next: val => console.log(`NEXT VALUE: ${val}`),
      error: val => console.log(`ERROR VALUE: ${val}`),
      complete: val => console.log(`COMPLETE`)
    });

Observables:

public runInstructionAndGetResult(): Observable<string> {
    return this.runAnInstruction()
        .flatMap((data) => {
            console.info("flatMap of runAnInstruction:", data);
            return this.getInstructionExecutionStatusInPolling()
                .filter(data => data != "Polling")
                .take(1)
                .flatMap((data) => {
                    console.info("flatMap of getInstructionExecutionStatusInPolling:", data);
                    return this.getInstructionResult();
                }).map((data) => {
                    console.info("Map of getInstructionResult:", data);
                    return data;
                });
        });
  }

  public runAnInstruction(): Observable<string> {
    return Observable.of("StartRun");
  }

  public getInstructionResult(): Observable<string> {
    return Observable.of("FinalResult");
  }

  public getInstructionExecutionStatusInPolling(): Observable<string> {
    return Observable.interval(1000)
        .concatMap(data => {
            return this.getInstructionExecutionStatus();
        });
  }

  public getInstructionExecutionStatus(): Observable<string> {
    return Observable.of("Polling", "Terminate");
  }

Here plunk: https://plnkr.co/edit/c1cahMtVARQnLgnHWlEe?p=preview

Main problem is that i just would like to be notify about "evolution" of inner stream outside.

Right now we have "next" event on main only when all inner flatMap are completed.

How to get notify? How can i emit explicit values to main stream for example during polling?

Thanks.

回答1:

I found a solution to share.

Here plunker updated:

https://plnkr.co/edit/c1cahMtVARQnLgnHWlEe?p=preview

Basically i create a simple observable using : https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/core/operators/create.md

then i call programmatically next method and complete finally:

 public runInstructionAndGetResult(): Observable<string> {
    return Observable.create((ops)=> {
      ops.next(1);
      this.runAnInstruction()
        .concatMap((data) => {
            ops.next(2);
            console.info("flatMap of runAnInstruction:", data);
            return this.getInstructionExecutionStatusInPolling()
                .filter(data => data != "Polling")
                .take(1)
                .concatMap((data) => {
                    ops.next(3);
                    console.info("flatMap of getInstructionExecutionStatusInPolling:", data);
                    return this.getInstructionResult();
                }).map((data) => {
                    console.info("Map of getInstructionResult:", data);
                    ops.next(4);
                    ops.complete();
                    return data;
                });
        }).subscribe();
        });
  }

来源：https://stackoverflow.com/questions/40992711/notify-from-inner-flatmap

标签

rxjs

rxjs5