从Firebase数据库检索计数数据 [英] Retrieve count data from Firebase database

问题描述

我有以下数据库.我需要的是发布 UID 等于current_user_uid时获得每个帖子的评论总数.

I have the following database. What I need is to get the total count of comments per post when posting UID equal to current_user_uid.

关于如何执行此操作的任何建议?

Any suggestion on how to do this?

推荐答案

要解决此问题，请使用以下代码:

To solve this, please use the following code:

String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
Query query = rootRef.child("Posts").orderByChild("uid").equalTo(current_user_uid);
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            long count = ds.child("comments").getChildrenCount();
            Log.d("TAG", "Count: " + count);
        }
    }

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

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