How to get last emitted value of on Observable in the subscription when next is called after the subscription?

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How can I subscribe and log the last value when next is called after subscription ?

Here is the working demo stackblitz, how or is it possible to get value only the last value i.e.123 that is emitted after the subscription inside the subscribe method or any other alternative ? I used last() but it doesn't logs any value at all. I want the subscription to run only once and use the last value

    import { Component, Input, OnInit } from '@angular/core';
import { BehaviorSubject, Observable } from 'rxjs';
import { last } from 'rxjs/operators';

@Component({
  selector: 'hello',
  template: `
    <h1>Hello {{ name }}!</h1>
  `
})
export class HelloComponent implements OnInit {
  @Input() name: string;
  subject = new BehaviorSubject<any>({});

  ngOnInit() {
    this.subject.next(456);

    this.getData()
      // .pipe(last())
      .subscribe(console.log);

      // this next is being done in another component after subscription so putting it here to mimic the behavior
     this.subject.next(123);

  }

  getData(): Observable<any> {
    return this.subject.asObservable();
  }
}
rxjs angular
1 Answers

You cannot use last() as the subject does not currently complete. You need to call complete() on the subject to be able to use it:

ngOnInit() {
  this.subject.next(456);

  this.getData()
    .pipe(last())
    .subscribe(console.log);

  this.subject.next(123);
  this.subject.complete();
}

Your StackBlitz

user_62940720
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