Component with focus on the constructor

app.component.ts

import { Component } from '@angular/core';
import { AngularFireDatabase, FirebaseListObservable } from 'angularfire2/database';
import { AF } from '../providers/af';
import { HttpModule } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import { AngularFireAuthModule, AngularFireAuth } from 'angularfire2/auth';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  public items: FirebaseListObservable<any[]>;
  public user: FirebaseListObservable<any>;
  constructor(db: AngularFireDatabase, public afService: AF, public afAuth: AngularFireAuth) {
    this.afAuth.authState.subscribe(res => {
      if (res && res.uid) {
        this.user = db.list('users/' + res.uid);
      }
    });
  } ...