Initial value of ObservableMedia not received

[erikkolo]

If I subscribe to ObservableMedia, the first (initial) value ist not received.
plunker.

The plunker example never receives the first value. In my own app, I get this first value in "xs" and "sm" size. If my browser windows is larger (gt-sm) at the time of loading the app (or refreshing), I do not get the first value.

[intellix]

Dupe: #240

[rolandjitsu]

#240 was closed despite the fact that this is an issue that more than one user is experiencing.

[rolandjitsu]

I also think I know what the issue is (or might be). Right now, I'm subscribing to the ObservableMedia in a ngOnInit() block, whereas if I subscribe to it in a constructor it seems to be triggered. So I wonder if the ObservableMedia acts as a Subject or BehaviorSubject?

The behaviour I'm experiencing leads to the conclusion it's probably not a BehaviorSubject, but it should be. As a user, when I subscribe to it, I'd expect to get the last registered value.

I haven't looked at the actual implementation, but I guess this might be the reason why some users don't see a value on subscribe, or at least that's why I don't.

[karser]

As a possible workaround I created an intermediary service that keeps MediaChange value in a ReplaySubject and it's initialized in AppComponent. So you can subscribe on MediaReplay.subject$ within your app.

export class MediaReplay {
    private _media$: ReplaySubject<MediaChange> = new ReplaySubject(1);

    constructor(media:ObservableMedia) {
        media.asObservable()
            .subscribe(res => this._media$.next(res), err => this._media$.error(err), () => this._media$.complete());
    }

    get media$(): Observable<MediaChange> {
        return this._media$.asObservable();
    }
}

export class AppComponent {
    constructor(mediaReplay: MediaReplay) {} //so it's initialized when the app starts
}

[jurafa]

IMHO this is a quite serious issue. It makes the JavaScript API unreliable. Are the developers going to fix this anytime soon?

[ThomasBurleson]

This will be fixed by next week and included in the upcoming Beta.9 Release.

[ThomasBurleson]

ObservableMedia uses BehaviorSubject internally; however it only reports breakpoint activations. This issue 245 is a bug. We are investigating.

[ThomasBurleson]

Will be fixed with PR #313.

See working plunker: https://plnkr.co/edit/yylQr2IdbGy2Yr00srrN?p=preview

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