di-inverted.component.ts

@Injectable()
export class SomeService {
    data = 10;

    updateData() {
        this.data = 20;
    }
}

@Component({
    selector: 'app-di-child',
    template: `{{someService.data}}`,
    // `SomeService` is only provided here
    providers: [SomeService]
})
export class DiChildComponent {
    someService = inject(SomeService);
}

@Component({
    selector: 'app-di-parent',
    template: `
        <app-di-child/>
    `,
    imports: [DiChildComponent],
    // here `SomeService` is NOT provided, so we might 
})
export class DiParentComponent implements OnInit {
    child = viewChild.required(DiChildComponent, {read: ViewContainerRef});
    someService!: SomeService;
    // we can't do `someService = inject(SomeService);` 
    // here, because `SomeService` is not provided in this component

    ngOnInit() {
        // instead, we can use the injection context of the child component
        this.someService = runInInjectionContext(
            this.child().injector, 
            // and inject `SomeService` in that context, where it is provided
            () => inject(SomeService),
        );
        this.someService.updateData();
        // after this, the template of `DiChildComponent` will show `20`
    }
}