How do you prevent duplicate user properties in Firebase?

Question

I\'m Using FirebaseSimpleLogin to create users and handle authentication.

When I try and create a new user with simple login via the $createUser()

Answer 1

Wouldn't it be easier to just use the security rules to check for it's existence? I have mine set up as follows:

"usernames": {
  "$usernameid": {
    ".read": "auth != null",
        ".write": "auth != null  && (!data.exists() || !newData.exists())"
    }
    }

This allows the write if the username doesn't exist. I believe I got this directly from the Firebase docs.