Angular2: Are dynamically created injectors (created via Injector.create(...)) ever destroyed?

Question

Need some comments on the lifecycle of injectors created with Injector.create method

I tried to create a component via ViewContainerRef.createComponent(...) and provide dynamically generated dependencies using a custom injector that was passed in arguments. That injector had a parent injector inherited from the host component.

When after some time I destroyed that component, I noticed that the services I had provided in the dynamic injector didn't execute the ngOnDestroy method.

Nevertheless, all the services provided via @Component decorator (in the parent component) were successfully destroyed (in fact, they're always destroyed this way).

What can be the reason of such behaviour? Is there a way to destroy dynamically created injectors?

Here's an StackBlitz example: https://stackblitz.com/edit/stackblitz-starters-vstiqn

When I close the parent component via the toggle button, I expect that the ChildService would call ngOnDestroy method as the ParentService does.

Answer 1

The best way to destroy an Injector manually is to go with an EnvironmentInjector which has the destroy method.

With your example that would be :

export class ParentComponent implements OnInit, OnDestroy {
  myInjector?:EnvironmentInjector

  constructor(
    private readonly viewContainerRef: ViewContainerRef,
    private readonly environmentInjector: EnvironmentInjector,
    private readonly parentService: ParentService
  ) {}

  ngOnInit() {
    this.myInjector = createEnvironmentInjector( [ChildService],
      this.environmentInjector,
    ); // create

    this.viewContainerRef.createComponent(ChildComponent, {
      injector: this.myInjector,
    });
  }

  ngOnDestroy() {
    this.myInjector?.destroy() // destroy
    console.log('ParentComponent destroyed'); 
  }
}