Any counterpart for constructor? (Provider/Service)

Ionic Framework ionic-v3
1

Hi! Simple question, are there any counterpart for constructor? I need to clear some things to avoid leaks so I am looking for the function that gets called before the PROVIDER is destroyed.

It is ionViewWillUnload for Pages right? how about for Service/Providers?

Thanks.

2

Global providers are never destroyed.

3

how about? ngOnDestroy()? When the app is closed on background?

4

That’s a component life cycle hook. Providers aren’t components.

5

Platform has pause and resume events that might be what you are looking for.

6

So there are no way to clear my subscriptions contained inside a provider class? Thanks for the clarifications.

7

Of course there are.

subscription: Subscription = new Subscription();

startListening() {
  subscription = someObservable.subscribe(x => console.log(x));
}
stopListening() {
  subscription.unsubscribe();
}
8

No what I meant is before the app is closed, I want to clear all of my subscriptions by calling unsubscribe in each and every subscription, just to avoid leaks, or it doesn’t matter because…

I’ve read somewhere that:
“For other types of injectable (service, factory, provider) the concept of a destructor is probably not useful, since they are singletons which last for the duration of the app’s life.”

9

Call your stopListeners before logging out. If the app is closed forcefully by the user, the Observables stop. But you control the soft landing.

1 Like
10

Makes sense, thanks for the clarification.

1 Like
11

Thanks for this suggestion.