Firebase increases Long values itself

Question

I am building an app which have qr codes and its scanner i want to keep to record of how many times each qr code is being scanned but Firebase increases values itself...i want to increment value by one when qr code is scanned.

 valueEventListener1 = reference2.addValueEventListener(new ValueEventListener() 
                   {
                        @Override
                        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                            reference1.removeEventListener(valueEventListener);
                            if (dataSnapshot.hasChild("count")) {
                                long c = dataSnapshot.child("count").getValue(Long.class);
                                final DatabaseReference reference3 = FirebaseDatabase.getInstance()
                                        .getReference(Utils.ALL_USERS).child(coupon_user_uid)
                                        .child(Utils.USED_COUPONS).child(id);

                                reference3.child("coupon_id").setValue(id);
                                reference3.child("coupon_owner_uid").setValue(coupon_owner_uid);
                                reference3.child("count").setValue(c++)
                                .addOnCompleteListener(new OnCompleteListener<Void>() {
                                    @Override
                                    public void onComplete(@NonNull Task<Void> task) {
                                        reference2.removeEventListener(valueEventListener1);
                                    }
                                });

it continuously increase the value until i shut the app down — Rabi Rafique, May 12 '20 at 14:53
If you need to increase the value of a property you should use transactions, as explained the duplicate. — Alex Mamo, May 13 '20 at 09:22

score 0 · Answer 1 · answered May 12 '20 at 18:53

Maybe its because the listener is invoking itself again each time a write is done. Try to use ListenerForSingleValueEvent, like this:

valueEventListener1 = reference2.addListenerForSingleValueEvent(new ValueEventListener() 
{
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
...............
...............
...............

Firebase increases Long values itself

1 Answers1