Query firebase AngularFirestoreCollection using multiple Ids

I’ve asked this on stackoverflow, I feel like it’s relevant here as well.

I’m passing an array of Province Ids provinceIds and I wanna query and return all Universities within each Province . So far I’m only returning universities from the first Province. There are exactly 9 possible Ids that can be passed (9 South African provinces). I tried iterating, and I just ended with a lot of weird code that ‘I’ didn’t understand myself.

If you know any other way to do this, I’m open.

export class UniversitiesService {
  private collection: AngularFirestoreCollection<University>;
  universities: Observable<University[]>;
    private afs: AngularFirestore
  ) { }

  getUniversitiesByProvince(provinceIds: string[]): Observable<University[]> {
    this.collection = this.afs.collection('Universities',
        ref => ref.where('provinceID', '==', provinceIds[0]));
    this.universities = this.collection.snapshotChanges()
      .map(actions => {
        return actions.map(a => {
          const data = a.payload.doc.data() as University;
          data.Id = a.payload.doc.id;
          return data;
    return this.universities;