CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
mshel
mshel

Reputation: 29

How to get data from firebase and then push it back

I stuck with getting data from firebase and then push it back after some changes.

The code given below work with issues, because I need to get int and push sum of its and another value to the Realtime Database once, but it push it multiple times, after last time it was more than 39K rows, except 1.

private DatabaseReference ratingReference =  FirebaseDatabase.getInstance().getReference().child(Consts.RATING_DB);

 public void setRating(String uid, int addPoint) {
        ratingReference.child(uid).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                int rating = 0;
                if (dataSnapshot.child(Consts.RATING).getValue() != null) {
                    rating = Integer.valueOf(dataSnapshot.child(Consts.RATING).getValue().toString());
                }
                DatabaseReference ref =  ratingReference.child(getUid()).push();
                Map<String, Object> ratingMap = new HashMap<>();
                ratingMap.put("rating", rating + addPoint);
                ref.updateChildren(ratingMap);
            }
            @Override
            public void onCancelled(DatabaseError databaseError) {}
        });
    }

I`ll be really grateful, if you help me, thanks a lot.

Upvotes: 0

Views: 60

Answers (1)

Alex Mamo
Alex Mamo

Reputation: 138824

Assuming that the Consts.RATING holds a String value similar with rating and the type of this property is a number and not a String, to add the value of addPoint to the existing rating value, please use the following lines of code:

ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        long rating = 0;

        if(dataSnapshot.child(Consts.RATING).exists()) {
            rating = dataSnapshot.child(Consts.RATING).getValue(Long.class);
            long newValue = rating + addPoint;
            dataSnapshot.child(Consts.RATING).getRef().setValue(newValue);
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d(TAG, databaseError.getMessage());
    }
};
ratingReference.child(uid).addListenerForSingleValueEvent(valueEventListener);

As you can see, there is no need to use any push() call.

Upvotes: 1

Related Questions