angular-fire-install.ts

@NgModule({
  declarations: [
    AppComponent,
    ...
  ],
  imports: [
      BrowserModule,
      AngularFireModule.initializeApp(firebaseConfig),
      RouterModule.forRoot(routerConfig)  
],
  providers: [...],
  bootstrap: [AppComponent]
})
export class AppModule { }

gistfile1.txt

import {FirebaseRef} from "angularfire2";

@Injectable()
export class LessonsService {

    constructor( @Inject(FirebaseRef) fb) {

        const rootDbRef = fb.database().ref();
        
        ...
    }
    
}

lesson.json

{
  "url": "angular2-hello-world-write-first-application",
  "description": "Angular 2 Tutorial For Beginners - Build Your First App - Hello World Step By Step",
  "duration": "2:49",
  "tags": "BEGINNER",
  videoUrl: "https://www.youtube.com/embed/du6sKwEFrhQ",
  "longDescription": "This is step by step guide to create your first Angular 2 application. Its aimed at beginners just starting out with the framework.This lesson will show how to create a component, and how to link the component to a given custom HTML tag. It will show how to give the component a given template."
}

one-to-many-wrong.json

{
  "url": "angular2-hello-world-write-first-application",
  "description": "Angular 2 Tutorial For Beginners - Build Your First App - Hello World Step By Step",
  "duration": "2:49",
  "tags": "BEGINNER",
  videoUrl: "https://www.youtube.com/embed/du6sKwEFrhQ",
  "longDescription": "This is step by step guide to create your first Angular 2 application. Its aimed at beginners just starting out with the framework.This lesson will show how to create a component, and how to link the component to a given custom HTML tag. It will show how to give the component a given template."
  lessons: [
          {
          "url": "angular2-hello-world-write-first-application",
          "description": "Angular 2 Tutorial For Beginners - Build Your First App - Hello World Step By Step",
          "duration": "2:49",
          "tags": "BEGINNER",
          videoUrl: "https://www.youtube.com/embed/du6sKwEFrhQ",
          "longDescription": "This is step by step guide to create your first Angular 2 application. Its aimed at beginners just starting out with the framework.This lesson will show how to create a component, and how to link the component to a given custom HTML tag. It will show how to give the component a given template."
        },
        {
          "url": "angular2-build-your-first-component",
          "description": "Building Your First Angular 2 Component - Component Composition",
          "duration": "2:07",
          "tags": "BEGINNER",
          videoUrl: "https://www.youtube.com/embed/VES1eTNxi1s",
          "longDescription": "In this lesson we are going to see how to include a component inside another component. We are going to create a simple search box component and include it in our main application."
        },
        ...
  ]
}

read-whole-db.ts

import {initializeApp,database} from 'firebase';

export const firebaseConfig = {
    apiKey: "AIzaSyA0BcUcu4V8aHT_gM-32BhRcmqji4z-xts",
    authDomain: "some-app.firebaseapp.com",
    databaseURL: "https://some-app.firebaseio.com",
    storageBucket: "some-app.appspot.com",
    messagingSenderId: "290354329699"
};

initializeApp(firebaseConfig);

database().ref().on('value', snapshot => console.log(snapshot.val()));