The most efficient and hygienic method for retrieving a value based on an observable

Looking at the structure of my code, I see that there are numerous Observables and ReplaySubjects. When trying to extract a value from one of these observables in the HTML template, what would be the most effective approach? In certain situations, parameters from the template may also need to be considered.

public config$ = new ReplaySubject<Config>(1);

public getValue(foo: number): number {
  this.config$.pipe(take(1)).subscribe((config) => {
     // something like return config.value + foo;
  });
}

Answer №1

It is generally advisable to avoid using the subscribe method whenever possible, as it requires manual management of unsubscribing from the observable. A better approach is to utilize piping with observables and then implement the async pipe in your template. Another option is to employ

*ngIf="config$ | async as config"
to assign the latest value from the observable to the config variable in your template.

Within your controller:

public value$ = this.config$.pipe(take(1), map(config => config.x));

Subsequently, in your template:

Value x from the config: {{ value$ | async }}

For a functional demonstration, refer to this StackBlitz example.

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