Set key on user register object with firebase

Question

how can I change the unique Id key when pushing the registered details to Firebase?

 var ref = new Firebase(FIREBASE_URL + 'users');

 var userInfo = {
      date: Firebase.ServerValue.TIMESTAMP,
      userData: userData.uid,
      firstname: user.firstname,
      lastname: user.lastname,
      email: user.email
 }

 ref.push(userInfo);

Answer 1

I figured out you had to add child to the object declaration:

ref.child(userData.uid).set(userInfo);