RXJS Observable doSomething onComplete

问题:

I would like to use the RXJS Observable. Basically it works fine, but I need not just to react when observer.next() but also when observer.complete() is called. How do I get the event of OnComplete of an RXJS Observable? In my opinion the RXJS doc is confusing.

export class Service {
    myMethod():Observable<any> {
        return Observable.create((observer:any) => {
        for(let i=0; i<10; i++) {
         observer.next(i);
        }
        if(true==true) {
            // this event I need
            observer.complete();
        } else {
            observer.error(xhr.response);
        }
    }
}

export class Component() {
    // constructor etc.

    doSome() {
        this.service.myMethod()
        // Here I would like to get OnComplete event
          .catch(this.handleError)
          .subscribe((num:any) => {
            console.log(num);
        });
    }
}

回答1:

The subscribe method accepts three callbacks. The last one is for the complete event.

doSome() {
  this.service.myMethod()
      .subscribe((num:any) => {
        console.log(num);
      }, (err) => {
        this.handleError(err);
      }, () => { // <----
        this.handleComplete();
      });
}

You could also leverage the finally operator for this.

doSome() {
  this.service.myMethod()
      .catch(this.handleError)
      .finally(this.handleComplete) // <----
      .subscribe((num:any) => {
        console.log(num);
    });
}

note: there is a difference between the two examples in case we have errors: if we would add console.logs we would see that in the first case only handleError is printed

-> handleError

in the second case

-> handleError
-> finally

in other words finally is always called, were complete is not.

回答2:

As Thierry Templier answered one option is to leverage the finally/finalize (rxjs docs) (but it's not the same as using the complete event, see the notes)

---

last

Another option to do something on complete is last (rxjs/last)