返回一个常规数组而不是 Observable<t[]> 在 RxJS</t[]>

Question

New to observables. How do I return a regular array from this function instead of an observable?

removeRewards(userId: string): string[] {
  return this.getUsedRewards(userId).pipe(
  switchMap(rewards => rewards.filter(reward => reward.active)),
  map(reward => reward.rewardId),
  toArray()
  );
}

getUsedRewards returns an Observable. I'm calling removeRewards in a different function and just need this to return string[] instead of Observable<string[]>.

Please advise, thanks.

Answer 1

You must END the stream and then use toArray() to achieve your goal You can see this example

"get values emitted by interval as an array when interval completes "

// RxJS v6+
import { interval } from 'rxjs';
import { toArray, take } from 'rxjs/operators';

interval(100)
  .pipe(take(10), toArray())
  .subscribe(console.log);

// output: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

So u can do something like:

removeRewards(userId: string): string[] {
  return this.getUsedRewards(userId).pipe(
  switchMap(rewards => rewards.filter(reward => reward.active)),
  map(reward => reward.rewardId),
  take(1), // <-- ADD THIS LINE
  toArray()
  );
}

Also possible operator is first()

Answer 2

If it is an observable, you have to subscribe it to get whatever observable emits and then use it in whatever way you want.