AngularFireDatabase doesn't execute functions when an empty list should be returned

[mateusduraes]

Hello, seems like the AngularFireDatabase is not handling empty lists in the observables.

constructor(private afDb: AngularFireDatabase) {}
// ommited code
public userExists(email: string): Observable<boolean> {
  return this.afDb.list('/clients', ref =>
    ref.orderByChild('email').equalTo(email))
    .valueChanges()
    .map((users: User[]) => users.length > 0);
}

When i call the method with an email that exists in my realtime database, everything is fine, but if the observable should return an empty list, it is not triggered.

[guillefd]

Same here, also snapshotChanges() doesn´t trigger when list is empty

[jamesdaniels]

K, I fixed in AFS I'll grab AFDB tonight + cut a new RC.

[jamesdaniels]

FYI this is a little trickier with RTDB + the new arch. Still in progress.

[yaozuwang]

Thanks James

[DennisSmolek]

Heads up, getting this as well...
core firebase.js says a snapshot should return null if empty but with the latest angularFire I dont get anything until a value exists.

return this.af.list('/revisions/' + contentId + '/' + draftId).valueChanges(); and snapshotChanges() are both never firing their subscriptions..

but:

const ref = firebase.database().ref('/revisions/' + contentId + '/' + draftKey);
                    ref.once('value', snapshot => {
                        console.log('Firebase once returning:', snapshot.val());

fires with Firebase once returning:null

I had the listener setup with later functions init() binding inside the callback and my app just paused waiting for the callback....

[hvsharma63]

This issue still exists. When where queries are added in collection via reference & if the collection is empty, the subscription is not fired, on .valueChanges()