Making user online of Firestore and Firebase

MainActivity.kt

fun makeUserOnline(user: UserModel)
{
    // Firestore
    var query = FirebaseFirestore.getInstance().collection("users").document(user.userId ?: "")
    user.apply {
        online = true
        last_active = 0
    }
    query.set(user)
    
    // Firebase Status
    var fbquery = FirebaseDatabase.getInstance().getReference("status/" + user.userId).setValue("online")

}