Find if a value exist on Firebase with Kotlin

Question

I'm starting on kotlin and Firebase

I'm using the AuthUI to login users, and would like to store some additional information (Profile Picture, Adresse, etc).

I have a collection of "Users" to store that information, as well as the User Id.

I'm trying to search if given a User Id, there's no information about it (That would happen after the user signs up using the AuthUI) and in that case, I'll call a new Activity to welcome the user to the app and ask for the additional information.

I can't find a way to search for it, using kotlin...

Thank you in advance

Please check the duplicate and instead of using the username, you can use the `uid`. — Alex Mamo, Apr 14 '20 at 10:28

score 0 · Answer 1 · answered Apr 14 '20 at 00:19

0

Just try to fetch data with the id. If the query comes up with nothing, the data doesn't exist.

answered Apr 14 '20 at 00:19

oittaa

599
3
16

score 0 · Answer 2 · answered Apr 14 '20 at 01:31

i've used several code i found online. Currently i'm doing this:

fun checkIfUserExists(userId : String) {
val rootRef = FirebaseDatabase.getInstance().reference
val userNameRef = rootRef.child("users").child(userId)
val eventListener: ValueEventListener = object : ValueEventListener {
    override fun onDataChange(dataSnapshot: DataSnapshot) {
        if (!dataSnapshot.exists()) {
            //create new user
        }
    }

    override fun onCancelled(databaseError: DatabaseError) {

    }
}
userNameRef.addListenerForSingleValueEvent(eventListener)}

The code runs but it nevers executes the onDataChange...

My db is currently emptyenter image description here

Find if a value exist on Firebase with Kotlin

2 Answers2