firebase firestore read a specific document in angular

user_7832946 0
Viewed 4985

I want to read a specific document in Firebase Firestore using AngularFire. 

import { Component, OnInit } from '@angular/core'; 
import { ActivatedRoute } from '@angular/router';
import { AngularFirestore , AngularFirestoreCollection, AngularFirestoreDocument } from 'angularfire2/firestore';
import { Observable } from 'rxjs';
import { async } from 'q';

@Component({
  selector: 'app-read-more-page',
  templateUrl: './read-more-page.component.html',
  styleUrls: ['./read-more-page.component.scss']
})
export class ReadMorePageComponent implements OnInit {
  postCatagory: string;
  databaseName: any; 
  uuid: string;

  documentObject:any; //real docum

  //observables 
  items: Observable<any[]>;
  doc  : AngularFirestoreDocument<any>
  post : Observable<any>;

  constructor(private route: ActivatedRoute , private afs: AngularFirestore ) {
    this.databaseName = this.route.snapshot.paramMap.get('category'); 
    this.items = afs.collection(this.databaseName).valueChanges();
  }   

  ngOnInit() {
    if(this.route.snapshot.paramMap.get('uuid') != null){ 
      //when id is not null   
      this.databaseName = this.route.snapshot.paramMap.get('category');
      this.uuid = this.route.snapshot.paramMap.get('uuid');
      console.log("UUID " , this.uuid);
      console.log("category "  ,this.databaseName);
      //read data from collection 
      //read post 
      this.doc = this.afs.doc(`${this.databaseName}/${this.uuid}`); 
    }
  }
}

${this.databaseName}/${this.uuid} is the document I wanted to read. But as the example in firestore docs, we could easily read all the documents from the collection. But I need to retrieve only the exact document.

I'm still a beginner so I would be much thankful if you could provide some beginner-friendly content

angularfire2 google-cloud-firestore angular firebase javascript
2 Answers
const docRef = afs.collection('collectionName').doc('documentId');

it will give you document reference, then you can subscribe to snapshotChanges() or call data() or other methods

user_22794880

Access document data easily cheesily like so:

let data

try {
  const userDoc = this.afs.doc(`users/${uid}`)
  const snap = await userDoc.get().toPromise()
  data = snap.data()
} catch (err) {
  console.error(err)
  data = { videoGroups: [], roles: [] }
}

Obviously, the above lives in an async method.

If you are not using async await then this is what you want:

let data

const userDoc = this.afs.doc(`users/${uid}`)
userDoc.get().toPromise().then((snap) => {
  data = snap.data()
}).catch((err) => {
  console.error(err)
  data = { videoGroups: [], roles: [] }
})

Note that the above approach gets the document as it is at the point in time at which you requested it. This is called a snapshot. Liken this to taking / snapping a photo which takes a still image at a single point in time.

If you want to stream data from a single document then you should be using valueChanges() as seen here

Note that you need to subscribe() to valueChanges()

user_12058710
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