计算firebase中一个孩子的节点数 [英] count the nodes of a child in the firebase

问题描述

我在firebase中有这样的结构:

I have a structure like this in firebase:

在节点"postagens-curtidas"中，我需要对这个子节点进行计数，并将该值保存在"qtdCurtidas"节点中，如图所示.

Inside the node 'postagens-curtidas', I need to count this childrens and save this value at the 'qtdCurtidas' node, as the photo shows.

有没有办法做到这一点?

Is there a way to make this?

推荐答案

final long count;
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
ref.child("postagens-curtidas").addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            count = dataSnapshot.getChildrenCount();
        }

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

        }
    });

这是获取子节点总数的方法.

This is how you get the total number of children nodes.

假设您具有保存qtdCurtidas的密钥.您可以将其保存如下

Assuming you have the key where qtdCurtidas is saved. You can save it as follows

ref.child("postagens-curtidas").child("Your Key Here").child("qtdCurtidas").setValue(count);

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