英文:
How to read data from the Firebase realtime database
问题
我想从 Firebase 实时数据库中的特定节点读取数据。
这是我的 JSON 树：
{"user": "1","user_details": {"emails": ["valker@gmail.com"],"usernames": ["valk stone"]}}
我如何从 user 节点读取数据？
英文:
I want to read data from a particular node from the firebase realtime database.
This is my JSON tree:
{"user" : "1","user_details" : {"emails" : [ "valker@gmail.com" ],"usernames" : [ "valk stone" ]}}
How do I read data from the user node?
答案1
得分: 1
你可以通过监听器来读取数据。如果你阅读文档，你会了解到 SingleValueEvent 用于一次性读取数据：
ValueEventListener userListener = new ValueEventListener() {@Overridepublic void onDataChange(DataSnapshot dataSnapshot) {Log.d(dataSnapshot);}@Overridepublic void onCancelled(DatabaseError databaseError) {// 获取数据失败，记录信息Log.w(TAG, "loadPost:onCancelled", databaseError.toException());// ...}};DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();DatabaseReference usersRef = rootRef.child("user_details");usersRef.addListenerForSingleValueEvent(userListener);
英文:
You can read data with the help of listener. If you read docs you come to know that SingleValueEventis used for read data once :
ValueEventListener userListener = new ValueEventListener() {@Overridepublic void onDataChange(DataSnapshot dataSnapshot) {Log.d(dataSnapshot);}@Overridepublic void onCancelled(DatabaseError databaseError) {// Getting Post failed, log a messageLog.w(TAG, "loadPost:onCancelled", databaseError.toException());// ...}};DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();DatabaseReference usersRef = rootRef.child("user_details");usersRef.addListenerForSingleValueEvent(userListener);
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论