Allow for empty sets in AFS

[jamesdaniels]

Version info

Angular: 4.3.6

Firebase: 4.5.0

AngularFire: 5.0.0-rc.1

Other (e.g. Ionic/Cordova, Node, browser, operating system):

How to reproduce these conditions

https://stackblitz.com/edit/angularfire-db-api-fbad9p

Steps to set up and reproduce

Select filters which would reduce to empty set (e.g, large + blue).

Expected behavior

Empty set would be returned from valueChanges()

Actual behavior

valueChanges() is not updated

[BAWES]

Same would be nice for snapshotChanges() as well.

[mateusduraes]

It was released in 5.0.0-rc.2?
Because seems like empty sets still not being returned from valueChanges()

I have the following 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 my query should return an empty array, the map / observables is not fired.

[jamesdaniels]

hmmm, is this the realtime db? i've mostly been focused on the firestore side

[jamesdaniels]

If so, can you open a new issue?

[mateusduraes]

@jamesdaniels yeah, it is. I've opened the issue #1220
thanks

[swftvsn]

Should snapshotChanges also work? When I hit conditions that produce zero results, the list is not cleared, but displays the old results. This is due to the .snapshotChanges() never being called.

I can fix it by having .snapshotChanges().startWith([]).map(snapshots => {, but then there's a double call everytime there's data.

I have code like this:

return this.firestore.collection<Invoice>('invoices/9/invoices', ref => {
        
  const direction = sort.direction == 'asc' ? 'asc' : 'desc'
  let q: firebase.firestore.Query = ref.orderBy(sort.active, direction)

  if (state && state != InvoiceState.all) {
    q = q.where('state', '==', state)
  }

  if (page.pageIndex > 0 && page.pageIndex - 1 in this.lastVisible) {
    return q.startAfter(this.lastVisible[page.pageIndex - 1]).limit(limitSize)
  } else {
    return q.limit(limitSize)
  }

}).snapshotChanges().startWith([]).map(snapshots => {
  if (snapshots.length == limitSize) {
    this.rowCountSubject.next(Number.MAX_SAFE_INTEGER)
    snapshots.pop()
  } else {
    this.rowCountSubject.next(this.lastPageSize * page.pageIndex + snapshots.length)
  }
  if (snapshots.length > 0) {
    this.lastVisible[page.pageIndex] = snapshots[snapshots.length-1].payload.doc
  }
  const invoices: Invoice[] = []
  for (const snapshot of snapshots) {
    const $key = snapshot.payload.doc.id
    const data = { $key, ...snapshot.payload.doc.data() } as Invoice
    invoices.push(data)
  }
  return invoices
}).map(invoices => {
  const data = this.filterAndMap(invoices)
  return data
})

[swftvsn]

@jamesdaniels dropping you a message cause this issue is already closed. See previous comment.