Retrieving specific data from Firebase Database

Question

I'm creating a chat app on android using Firebase Database and Java. Whenever the user is first registered, it stores their username into the database under the nodes user/UserID/profile/username. The username is stored using a User class. This is where the username value is stored. However when I try something like

mDatabase.child("users").child(UserID).child("profile").child("username").toString();

This gives me the path to the username but not the username itself. Does anybody know how to get the value of the username itself?

EDIT: It gives me an error when I run

DataSnapshot.child("users").child(mUserID).child("profile").child("username").getValue().toString();

Here is what my Firebase database shows under the UserID.

Firebase database profile

BlackHatSamurai BlackHatSamurai · Accepted Answer · 2017-04-06T02:34:28

You aren't getting the value properly. You need to attach a listener to you child and get updates. You do that like this:

// Get a reference to your user
final FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference ref = database.getReference("server/path/to/profile");

// Attach a listener to read the data at your profile reference
ref.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        Profile profile = dataSnapshot.getValue(Profile.class);
        System.out.println(profile.getUsername());
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        System.out.println("The read failed: " + databaseError.getCode());
    }
});

You can find more information and examples on the Firebase website. Keep in mind that you don't make requests to get data from Firebase. You attach listeners to the children and then get the data from the listener. This example assumes that you have a Profile model, with a method to get the username. This would return your Profile object and would enable you to get whatever data you need off of that object.

Retrieving specific data from Firebase Database

2 Answers