[AngularFire 2 ] Hello World - How To Write your First Query using AngularFire 2 List Observables ?

In this lesson we are going to use AngularFire 2 for the first time. We are going to configure the AngularFire 2 module, inject the AngularFire service in our service layer and use it do our first Firebase query: we are going to retrieve a list of objects from the database.

Install:

//install 

npm install --save angularfire2

Import AngularFireModule in app.module.ts:

...
import {firebaseConfig} from "../environments/firebase.config";
import {AngularFireModule} from "angularfire2";

@NgModule({
  ...
  imports: [
    ...
    AngularFireModule.initializeApp(firebaseConfig)
  ],

Load the data in service: realtime.service.ts:

import { Injectable } from '@angular/core';
import {AngularFire, FirebaseListObservable} from "angularfire2";

@Injectable()
export class RealtimeService {

  constructor(private af: AngularFire) {
    const courses$: FirebaseListObservable<any> = af.database.list('courses');
    courses$.subscribe(
      val => console.log("val", JSON.stringify(val, null, ))
    )
  }

}

firebase database.list() method return 'FirebaseListObservable' type.