Is it possible to inject interface with angular2?

Question

i wonder if there is a proper way to inject interfaces in Angular2? (cf. below)

I think this is related with the missing @Injectable() decorator on the interface, bu

Answer 1

Alternate solution for angular 9

@Injectable()
export class TodoListPublicService implements TodoListService {
  getTodos(): Todo[] {
    const todos: Todo[] = [
      {
        title: 'get groceries',
        description: 'eggs, milk, etc.',
        done: false
      }
    ];

    return todos;
  }
}

create an abstract class

export interface Todo {
  title: string;
  description: string;
  done: boolean;
}

@Injectable()
export abstract class TodoListService {
  abstract getTodos(): Todo[];
}

Use in the component

providers: [
    { provide: TodoListService, useClass: TodoListPublicService }
  ]
export class TodoListComponent implements OnInit {
  todos: Todo[];

  constructor(private todoListService: TodoListService) { }

  ngOnInit() {
  }