Firebase Android - how to tell if node has been synced

Question

I'm using Firebase for Android for the chat component of our app. I'm having trouble figuring out how to reliably implement status updates on each chat message. For example, showing "Sending.." when the chat is being synced with the server, and having a success feedback after sync.

I have a onChildAdded listener that supplies the messages to my adapter. However, this listener is fired immediately when each node is added locally, and I can't check the status of each node

My Current solution is to keep a set of node keys, and add keys whenever I push something to Firebase. Then on the setValue callback, I remove the node key from the set. However, this is very unreliable since the nodes can be synced when the calling activity has been destroyed, etc.

I am wondering if there is a simpler way to check if each node has been synced to the server?

Thanks!

Answer 1

From the Firebase documentation on writing data:

If you'd like to know when your data has been committed, you can add a completion listener. Both setValue() and updateChildren() take an optional completion listener that is called when the write has been committed to the database.

With this handy code sample:

ref.setValue("I'm writing data", new Firebase.CompletionListener() {
    @Override
    public void onComplete(FirebaseError firebaseError, Firebase firebase) {
        if (firebaseError != null) {
            System.out.println("Data could not be saved. " + firebaseError.getMessage());
        } else {
            System.out.println("Data saved successfully.");
        }
    }
});