import { Component , OnInit } from '@angular/core' ; import { Observable } from 'rxjs' ; import { persistenceEnabled as _persistenceEnabled } from '../app.module' ; import { traceUntilFirst } from '@angular/fire/performance' ; import { doc , docData , Firestore } from '@angular/fire/firestore' ; @ Component ( { selector : 'app-firestore' , template : `<p>
    Firestore!
    <code>{{ testDocValue$ | async | json }}</code>
    <br>
    <small>Persistence enabled: <code>{{ (persistenceEnabled | async) ?? false }}</code></small>
  </p>` , styles : [ `` ] } ) export class FirestoreComponent implements OnInit { public readonly testDocValue$ : Observable < any > ; public readonly persistenceEnabled = _persistenceEnabled ; constructor ( firestore ) { const ref = doc ( firestore , 'test/1' ) ; this . testDocValue$ = docData ( ref ) . pipe ( traceUntilFirst ( 'firestore' ) ) ; } ngOnInit ( ) { } }