登录后如何将新用户数据保存到Firebase实时数据库 [英] How to save new user data to Firebase Realtime Database after Login

问题描述

我已经编写了一个函数，可以将新的用户数据写入这样的数据库

I have written a function to write new user data if needed to database like this

private void writeNewUserIfNeeded(final String userId, final String username, final String name) {
    final DatabaseReference usersRef = rootRef.child("users");

    usersRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (!dataSnapshot.hasChild(userId))
                usersRef.child(userId).setValue(new User(username, name));
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

但是问题是即使调用了该函数，也从未调用 onDataChange ，所以我无法保存新的用户数据.保存新数据的最佳做法是什么?

But the problem is the onDataChange never called eventhough the function is called, so I cannot save my new user data. How is the best practice to save the new data?

更新:添加规则这是我写的规则

{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null",
    "users": {
      "$uid": {
        ".read" : "$uid === auth.uid",
        ".write": "$uid === auth.uid"
      }
    }
  }
}

推荐答案

我已经解决了该问题.只需要添加 UID

I already fix the problem. Only need add child of the UID

private void writeNewUserIfNeeded(final String userId, final String username, final String name) {
    final DatabaseReference usersRef = rootRef.child("users").child(userId);

    usersRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (!dataSnapshot.exists())
                usersRef.setValue(new User(username, name));
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

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