How to inject a service into Angular scrollOffset function

Question

I'm trying to implemnent the scrollOffset method in the Angular router:

@NgModule({
    imports: [
        RouterModule.forRoot(
            routes,
            {
                anchorScrolling: 'enabled',
                scrollPositionRestoration: 'enabled',
                scrollOffset: () => {
                    // TODO: implementation
                },
            }
        )
    ]
})
export class AppRoutingModule { }

But would like to reference a service here. Does anyone know if theres a way to inject a provider into this method?

I've looked at the Injector but there isn't a static get() so I'm not sure how else to do it.

Thanks

Answer 1

You can't really inject a function. Based on angular DI documentation

Dependencies are services or objects that a class needs to perform its function. DI is a coding pattern in which a class asks for dependencies from external sources rather than creating them itself.

The scrollOffset awaits for either an array [number, number] or a function returning such an array. The function itself can't have a state as an object does, nor can it reference a function from a specific object.

scrollOffset?: [number, number] | (() => [number, number])

You can though declare your functions as a static class member and reference it from there.

Take note that the routes are declared as a const outside of any object, so even if you could reference a specific service function with state and all, there would be no constructor where you can inject this.

Answer 2

declare a injector globally then use it to get your service could work:

import {Injector} from 'angular2/core';

let appInjectorRef: Injector;
export const appInjector = (injector?: Injector):Injector => {
	if (injector) {
	  appInjectorRef = injector;
	}

	return appInjectorRef;
};

instantiate it in main.ts:

bootstrap(...).then((appRef: ComponentRef) => {
  appInjector(appRef.injector); // store a reference to the application injector
});

then use the injector declared in your routing:

scrollOffset: () => {
    appInjector().get(YourService)
}