如何从Android中的Firebase获取子节点的子节点？

Question

：

class UserAccountSettings {
    private String user_id;
    private String name ;
    private float rate;
    private String profile_photo;
    private ArrayList<Activity> activities ;
} 

感谢您的帮助！

Answer 1

要显示这些值，请使用以下代码：

String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference activitiesRef = rootRef.child("user_account_settings").child(uid).child("activities");
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String user_id = dataSnapshot.child("user_id").getValue(String.class);
        String name = dataSnapshot.child("name").getValue(String.class);
        float rate = dataSnapshot.child("rate").getValue(Float.class);
        String profile_photo = dataSnapshot.child("profile_photo").getValue(String.class);
        Log.d("TAG", user_id + " / " +
            profile_photo + " / " +
            rate + " / " +
            profile_photo);
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
activitiesRef.addListenerForSingleValueEvent(valueEventListener);

输出将是：

mVeg... / Debbebi / 0 / http://...

Answer 2

1. 声明一个Data baseReference对象（编辑字符串＆＃34; azone＆＃34;以匹配您的节点密钥）：

   DatabaseReference userSettingRef = 
                   FirebaseDatabase.getInstance().getReference()
                           .child("azone")
                           .child("user_account_settings")
                           .child(getUserId());
   

2. 添加ValueEventListener：

   userSettingRef.addValueEventListener(new ValueEventListener() {
                   @Override
                   public void onDataChange(DataSnapshot dataSnapshot) {
                       // Get Post object and use the values to update the UI
                       UserAccountSettings setting = dataSnapshot.getValue(UserAccountSettings .class);
                   if (setting!= null) {
                      // do something here
   
                   }
   
               }
   
               @Override
               public void onCancelled(DatabaseError databaseError) {
                   // Getting Post failed, log a recipientMessage
                   Log.w(TAG, "loadPost:onCancelled", databaseError.toException());
                   // ...
               }
           });