Firestore query a filed against multiple values

Question

Is it possible to query documents fields against an array of values where it would return the fields which contain one of the array elements values

                 _fireStore
                .collection('articles')
                .orderBy('created')
                .where('projectName', isEqualTo: listHearted)
                .getDocuments()
                .asStream(),

Answer 1

There is currently no way to perform a query that returns items that match one of a number of values in a certain field. The workaround is to perform a query for each hearted project, and merge the results on the client.

Also see:

• How to perform compound queries with logical OR in Cloud Firestore?
• Firebase Firestore - OR query
• Firestore - query all documents which field matches values in a list (like SQL IN)
• Firebase Query Or'ing whereEqualTo for a list of possible values
• Cannot query Firestore database on multiple values
• this tracking issue on Github

Answer 2

i've done it using a stream within a stream.

 Stream<List<DocumentSnapshot>> streamDoc;
  StreamController<List<DocumentSnapshot>> controller =
  StreamController<List<DocumentSnapshot>>();

 void docRef() {
Firestore _fireStore = Firestore.instance;

Stream<QuerySnapshot> snapshot = _fireStore
    .collection('articles')
    .orderBy('created')
    .getDocuments()
    .asStream();

List<DocumentSnapshot> listDoc = List<DocumentSnapshot>();
snapshot.listen((snapshot) {
  snapshot.documents.forEach((e) {
    if (SharedPrefList.listHearted
            .contains(e.data['projectName'].toString()) &&
        widget.type == 'hearted') {
      listDoc.add(e);
      controller.add(listDoc);
    }
    if (SharedPrefList.listSeen
            .contains(e.data['projectName'].toString()) &&
        widget.type == 'seen') {
      listDoc.add(e);
      controller.add(listDoc);
    }
  });
});

}