How to return a subscription in angular

Question

How do you return a subscription in Angular that is being called on an injectable?

So what I did at first that took me an hour to figure out is this:

 returnURLNotes(): Observable<any> {
    return this.store.select(selectDentureDesignNotes).subscribe((notes) => {
      if (
        notes &&
        notes[this._CANVAS_NAME] &&
        notes[this._CANVAS_NAME].length > 0
      ) {
        return notes[this._CANVAS_NAME];
      }
    });
  }

See the first return? I just returned the store.selector and this approach doesn't work. because the inner return won't be available as a return value of returnURLs method.

So here's my solution. It's working but I don't know if this is the right way.

returnURLNotes(): any {
    let URLs = {};
    const URLNotes$ = this.store.select(selectDentureDesignNotes);
    URLNotes$.subscribe((notes) => {
      if (
        notes &&
        notes[this._CANVAS_NAME] &&
        notes[this._CANVAS_NAME].length > 0
      ) {
        URLs = notes[this._CANVAS_NAME];
      }
    });

    return URLs;
  }

But I don't feel like that this is the right way because of JS single-threaded or "asynchronousity."

supersighs · Accepted Answer · 2019-04-21 03:57:45Z

1

Your first example shows you are trying to return an observable. This is how you would do that using rxjs using what you have provided. This utilizes rxjs filter and map. You probably dont want to return the subscription directly, but rather subscribe to the observable your function is returning.

returnURLNotes(): Observable <any> {
    return this.store.select(selectDentureDesignNotes).pipe(
        filter(notes => notes &&
            notes[this._CANVAS_NAME] &&
            notes[this._CANVAS_NAME].length > 0),
        map(notes => notes[this._CANVAS_NAME])
    );
}

edited Apr 21, 2019 at 3:57

answered Apr 21, 2019 at 3:30

supersighs

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2 Comments

aRtoo Over a year ago

so this will return the values or I still have to subscribe on the method that is using this?

supersighs Over a year ago

it will return an observable of the values, so you would do something like returnURLNotes().subscribe(...);

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