如何在Firebase中将旧数据与新数据相加 [英] How to sum older data with new one in firebase

问题描述

我有一个名为poin和kegiatan的表，当我向kegiatan输入得分时，也将其输入为poin，问题是当我输入score到poin并将其与poin中的旧数据求和时，它会反复循环.我应该怎么办?顺便说一句，这就是我的数据库和用于输入乐谱的代码.

I have table named poin and kegiatan, when I input score to kegiatan, its input to poin too, the problem is when I input score to poin and sum it with older data in poin, its will looping over and over. what should I do? Btw, this is how my database and code for input score to poin look like.

kegiatan+用户ID-点=分数in+ stringDate-userId =得分

reference = FirebaseDatabase.getInstance().getReference();
reference.child("poin").child(stringdate).child(nama).addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
        Integer previousScore = dataSnapshot.getValue(Integer.class);
        if (previousScore != null){
            Integer nita = previousScore + 2;
            dataSnapshot.getRef().setValue(nita);
        }else {
            dataSnapshot.getRef().setValue(0);
        }

        Toast.makeText(getActivity(),"Jumlah : "+nita, Toast.LENGTH_LONG).show();
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {

    }
});

我将date作为孩子，我如何每天添加新孩子?谢谢你的进步

and I use date as child, how can I add new child everyday? thanks for advance

推荐答案

我建议您存储所有点(点)并进行总计.示例数据库，您可以更改类似的内容.

I would suggest you store all points (poin) and total them up. Example database you can change something like this.

 -poin
  -stringDate
   -userId
     -poinUid1
       -score : 100
     -poinUid2
       -score : 200

所以这样的代码.您会得到一磅钱的总和.如果您想一次读取数据，但我更改了 addListenerForSingleValueEvent ，但是如果需要始终读取的数据，则需要使用 addValueEventListener .

so code like this. you get the total sum of poin. I changed addListenerForSingleValueEvent if you want to read the data once but if you have data which is NEED to read always, you need to use addValueEventListener.

//Get all the sums and display. 
FirebaseDatabase.getInstance().getReference().child("poin").child(stringdate).child(userId).addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
        if (dataSnapshot.exists()) {
            long sum = 0;
            for (DataSnapshot snapShot : dataSnapshot.getChildren()) {
                if (snapShot.exists()) {
                    long size = snapShot.child("score").getValue(Long.class);
                    sum += size;
                    textViewTotal.setText(String.valueOf(sum));

                }

            }
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {

    }
});

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