Firebase upvote adding id which doesn't exist

Question

I'm having a problem when I try to star a movie which id doesn't exist in my likes firebase node. Here's my code:

private void onStarClicked(long releaseId, final String uid) {
    final DatabaseReference postRef = ((GamePageActivity)getActivity()).mDatabaseRef.child("likes").child(mRegion).child(String.valueOf(releaseId));
    postRef.runTransaction(new Transaction.Handler() {
        @Override
        public Transaction.Result doTransaction(MutableData mutableData) {
            _Post p = mutableData.getValue(_Post.class);
                            if (p == null) {
                Log.d(TAG, "Transaction success");
                return Transaction.success(mutableData);
            }

            if (p.stars.containsKey(uid)) {
                // Unstar the post and remove self from stars
                p.starCount = p.starCount - 1;
                p.stars.remove(uid);
            } else {
                // Star the post and add self to stars
                p.starCount = p.starCount + 1;
                p.stars.put(uid, true);
            }

            // Set value and report transaction success
            mutableData.setValue(p);
            return Transaction.success(mutableData);
        }

        @Override
        public void onComplete(DatabaseError databaseError, boolean b,
                               DataSnapshot dataSnapshot) {
            // Transaction completed
            Log.d(TAG, "postTransaction:onComplete:" + databaseError);
        }
    });
}

The problem is if my id "releaseId" doesn't exist in the database, the star won't get added in, I thought my code was supposed to first add the "releaseId" if it doesn't exist?

score 0 · Answer 1 · answered Jul 18 '18 at 17:28

It seems a bit complicated to try to add a movie inside your likes path during a ‘like’ transaction. Ideally, it would already be there. So it will be easier to separate adding the movie to the likes path, and after that use a Cloud Function onCreate or onUpdate.

I assume you have your movie data somewhere else in your database. Let’s call it the ‘movies’ path for now. One idea to try is to have a Cloud Function that watches your ‘movies’ path, and when a movie is added, the function will add that movie data to your ‘likes’ path. That way, once a user tries to like a movie, its information is already in the correct spot in the database. Fixing the problem of the non-existent 'releaseId'.

Firebase Realtime Database Triggers

If you don’t want to use a Cloud Function, you can consider writing to both the ‘movies’ path and ‘likes’ path directly from the client when the movie is added, to accomplish the same thing.

Firebase upvote adding id which doesn't exist

1 Answers1