ngOnChanges not firing when attribute changed by Observable/subscrption

Question

I\'m trying to do something after an Observable/subscribe completes. I\'m changing an Input property in the subscribe( onNext )<

Answer 1

As stated by Günter it doesn't quite work like that from my understanding... When using Observables you can trigger a change manually with the Observable.next() feature. The trick here is that you will have to return an Observable from your service- this can be done like so:

import {Observable, Subject} from "rxjs/Rx"; // remember the '/Rx', it got me...

export class NamesService {
    private initialNames: Array<string> = ["Joe", "Jack", "Pete"];

    get(){
        let names: Subject<Array<string>> = new Subject<Array<string>>();

        names.next(this.initialNames);
        setTimeout(() => {
            this.initialNames.push('someOtherNames');
            names.next(this.initialNames);
        }, 1000);
        return names.asObservable();
    }
}

And then subscribe to it much as you have already done, and when the .next() runs it will trigger a change on the .subscribe() method.

I would recommend splitting this up from the get method though, you could possible have your own onNameUpdate() method that return the observable array- or something like that.

Answer 2

That's "as designed"

ngOnChanges() is only called when change detection updates a binding to an @Input(). If the input is changed imperatively from somewhere then it isn't called.

Just make names a getter/setter for code to be executed every time when the property is updated.