Angular & AngularFire 5 Retrieve Data From Document

Question

What I'm Using

• Angular 5
• AngularFire5
• Firebase & Firestore

What I'm Trying to Achieve

I am currently using Google Firebase's new Firestore to create a new app while learning angular. My app currently creates a collection called Links and creates a new document with a custom id that is generated when the user adds a link and is the shorturl, and in that document, there are 4 fields:

• uid
• url
• shorturl
• clicks

I want the app to query the data that is within the document in the url field.

What I have So Far

I've created a path to the correct document:

  linkCollection: Observable<{}>;
  constructor(private afs: AngularFirestore, private router: Router) {
      this.path = this.router.url.replace('/','');
      afs.collection('Links').doc(this.path).valueChanges();
  }

Where I'm Stuck

This is probably an easy solution but im not sure how to get the url field. The code I have is able to retrieve the document and I use a similar method in another section to retrieve all of the thinks and using *ngFor display the data but im not sure how to do it in the ts file instead of the template.

Answer 1

Here's the basic pattern you would follow to read a document as an Observable and use its data in a component template.

  linkRef: AngularFirestoreDocument<any>;
  link: Observable<any>;
  path: string;

  constructor(private afs: AngularFirestore, private router: Router) {}

  ngOnInit() {
    // 0. this works, but there's probably better ways to get the ID
    this.path = this.router.url.replace('/','');

    // 1. make a reference
    this.linkRef = this.afs.collection('links').doc(this.path)

    // 2. get the Observable
    this.link = this.linkRef.valueChanges();
  }

Then in your HTML, you can unwrap the observable and display the URL property.

{{ (link | async)?.url }}

Alternatively, can unwrap it by subscribing manually somewhere in the TS, but you should also unsubscribe during NgOnDestroy to avoid memory leaks.

this.link.subscribe(data => console.log(data) )