Pass config data using forRoot

I am trying to pass config data into a custom library in Angular.

In the users application, they will pass some config data to my library using forRoot

// Import custom library
import { SampleModule, SampleService } from 'custom-library';
...

// User provides their config
const CustomConfig = {
  url: 'some_value',
  key: 'some_value',
  secret: 'some_value',
  API: 'some_value'
  version: 'some_value'
};

@NgModule({
  declarations: [...],
  imports: [
    // User config passed in here
    SampleModule.forRoot(CustomConfig),
    ...
  ],
  providers: [
    SampleService
  ]
})
export class AppModule {}

---

In my custom library, specifically the index.ts, I can access the config data:

import { NgModule, ModuleWithProviders } from '@angular/core';
import { SampleService } from './src/sample.service';
...

@NgModule({
  imports: [
    CommonModule
  ],
  declarations: [...],
  exports: [...]
})
export class SampleModule {
  static forRoot(config: CustomConfig): ModuleWithProviders {
    // User config get logged here
    console.log(config);
    return {
      ngModule: SampleModule,
      providers: [SampleService]
    };
  }
}

My question is how do I make the config data available in the custom library's SampleService

Currently SampleService contains the following:

@Injectable()
export class SampleService {

  foo: any;

  constructor() {
    this.foo = ThirdParyAPI(/* I need the config object here */);
  }

  Fetch(itemType:string): Promise<any> {
    return this.foo.get(itemType);
  } 
}

I have read through the docs on Providers, however the forRoot example is quite minimal and doesn't seem to cover my use case.

You are almost there, simply provide both SampleService and config in your module like below:

export class SampleModule {
  static forRoot(config: CustomConfig): ModuleWithProviders<SampleModule> {
    // User config get logged here
    console.log(config);
    return {
      ngModule: SampleModule,
      providers: [SampleService, {provide: 'config', useValue: config}]
    };
  }
}

@Injectable()
export class SampleService {

  foo: string;

  constructor(@Inject('config') private config:CustomConfig) {
    this.foo = ThirdParyAPI( config );
  }
}

Update:

Since Angular 7 ModuleWithProviders is generic, so it needs ModuleWithProviders<SampleService>