check change from service variable angular
export class UserService { userDocumentReady: boolean = false; // initial value is "userdoc is not ready" userDocObserver: Subject<boolean> = new Subject<boolean>(); // observing that bool constructor( public fireauth: AngularFireAuth, public afs: AngularFirestore, ) { // watch variable this.userDocObserver.subscribe(value => this.userDocumentReady = value); this.fireauth.authState .subscribe(user => { if (user) { this.afs.doc(`/tooluser/${user.uid}`).snapshotChanges() .subscribe(usr => { if (usr.payload.data()) { console.log(`got user object from database:`, usr.payload.data()); this.currentUser = usr.payload.data(); this.userDocObserver.next(true); // flip UserDocumentReady flag
Source: stackoverflow.com