afire.service.ts

import { Injectable } from '@angular/core';
import {AngularFirestore, AngularFirestoreCollection} from 'angularfire2/firestore';
import * as faker from 'faker';

type todosCollection = AngularFirestoreCollection<any[]>;

@Injectable({
  providedIn: 'root'
})
export class AfireService {

  constructor(
    private afs: AngularFirestore,
  ) {}

  all (): todosCollection {
    return this.afs.collection('todos');
  }

  add (todoText: string): Promise<any> {
    const id = faker.random.alphaNumeric(16);
    const data = {
      id,
      todo: todoText
    };
    return this.afs.doc(`/todos/${id}`).set(data);
  }

  remove (id: string): Promise<any> {
    return this.all().doc(id).delete();
  }
}