how to add or remove item to the the existing array in firestore ?

Question

Firestore has recently add the new new method FieldValue.arrayUnion(value) and FieldValue.arrayRemove(value) but i couldn\'t find the implementation in flutter cloud_firesto

Answer 1

Here is the simple example to show how to update the array values. My document have an up voters array to add the user id's who have up-votes the document.

configure firestore, the config details can be copied form your google-services.json file

   final FirebaseApp app = await FirebaseApp.configure(
    name: 'test',
    options: const FirebaseOptions(
      projectID: 'projid',
      googleAppID: 'appid',
      apiKey: 'api',
      databaseURL: 'your url',
    ),
  );
  final Firestore firestore = Firestore(app: app);

  await firestore.settings(timestampsInSnapshotsEnabled: true);

update code using transaction

fireStore.runTransaction((Transaction tx) async {
            DocumentSnapshot snapshot =
                await tx.get(widget._document.reference);
            var doc = snapshot.data;
            if (doc['upvoters'].contains('12345')) {
              await tx.update(snapshot.reference, {
                'upvoters': FieldValue.arrayRemove(['12345'])
              });
            } else {
              await tx.update(snapshot.reference, {
                'upvoters': FieldValue.arrayUnion(['12345'])
              });
            }
          });

Hope it helps