Firebase check if user exists by display name

Question

I am trying to know if a user exists in Firebase (Email/Password Authentication) y only knowing the display name.

I am doing this is Android (Java).

Thank you so much!

Answer 1

There is no built-in support in Firebase Authentication to look up users by their display name. Given the loose definition of the meaning of the display name, it would be of limited use. Display names can't be required to be unique, since it's just a value that says how the user wants to be addressed: "When you show something from/to me, show this name next to it".

Many developers end up allowing their users to pick a username/nickname, which they then do require to be unique. If that approach make sense for your use-case too, I recommend reading some of these questions about how to accomplish this with the use of the Firebase Realtime Database:

• Firebase android : make username unique
• Enforcing unique usernames with Firebase simplelogin
• Firebase query if child of child contains a value (a more general explanation of uniqueness in the Firebase Realtime Database)
• How do you prevent duplicate user properties in Firebase?