FirebaseDatabase 显示来自单个用户的单个值

Question

Working on a small project at the moment on Android Studio and can't work out how I can print a single value from the current user. I am trying to get the current user's username to print, without printing all of the users other information such as email address...

Here is my database

I know I've got duplicates of everything, I've fixed that since :P

So far I've managed to print all of the user's details fine (unfortunately every user's details also printed)... using this code:

fDatabase = FirebaseDatabase.getInstance().getReference().child("Users");

    fDatabase.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String test = (String) dataSnapshot.getValue().toString();
            Log.d ("Testing", test);

The output I achieved can be found above.

and this is my User class:

class User {
String Displayname;
String Email;
Long createdAt;

public User () {}

public User(String displayname, String email, Long createdAt) {
    this.Displayname = displayname;
    this.Email = email;
    this.createdAt = createdAt;
}

public String getDisplaynames() {
    return Displayname;
}

public String getEmails() {
    return Email;
}

public Long getCreatedAts() {
    return createdAt;
}

My question is how can I get my output to print just: Testing: Chrisharvz

The reason I want to do this is so I can display the user's username as they log into my application, replacing Log.d with Textview.settext etc...

Anyone have an idea? If you need anymore information, lemme know! :D Thanks!

Answer 1

What I suggest is convert the data back into user object after you retrieve the data from firebase because right now you are using the whole object. You should try this:

    fDatabase =FirebaseDatabase.getInstance().getReference().child("Users");

    fDatabase.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            // convert the data back to the model
            User user = (User) dataSnapshot.child(currentUser.getUid()).getValue(User.class);
            // just get the string value for the username
            String displayName = user.getDisplayName() // getter method from your model
            Log.d ("Testing", displayName);
            }

Hopefully this helps your problem.

Answer 2

Assuming that Users node is a direct child of your Firebase database root and 0x2s4Ft... is the uid of the logged in user, to get the value only from your Displayname field, please use the following code:

FirebaseUser firebaseUser = firebaseAuth.getCurrentUser();
String uid = firebaseUser.getUid();

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("Users").child(uid);
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String Displayname = dataSnapshot.child("Displayname").getValue(String.class);
        Log.d("Testing: ", Displayname);
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
uidRef.addListenerForSingleValueEvent(eventListener);

Your output will be:

Testing: Chrisharvz