I am trying to fetch data from a document on a firebase’s collection that deos contains users(see image 1)enter image description here.
As you can see, there is a collection named Users and two users, and onw I click on one you get to see the fields and their values. Now, what I need is to retrieve the data within the documents (the fields values) and use it for my app, this is comenthing that ius easily accomplished in Java by using a class variable memmber. However, with Kotlin I can’t do that… so I can’t get the data I want out of the scope of the method addOnColeteListener (I use it like this db.collection().document().get().addOnCompleteListener{ // do stuff to retrieve data }, see code bellow). I realized that I gave more code that needed, but i wanted to add more context just jump right to the setUserIfno()

class MainActivity : ComponentActivity() {
    @RequiresApi(Build.VERSION_CODES.Q)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MyApplicationTheme {
                // A surface container using the 'background' color from the theme
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    val notificationsDatabase: DatabaseReference = FirebaseDatabase.getInstance().getReference()
                    val numberOfNotifications: Int = setNotifications(notificationsDatabase)
                    var currentUser: UserInfo
                    val mapOfUser: MutableMap<String, String?> = emptyMap<String,String?>().toMutableMap()
                    var dataSets = listOf<String>()
                    setUserInfo { user ->
                        currentUser = UserInfo().copy(
                            firstname = user.firstname,
                            lastname = user.lastname,
                            email = user.email,
                            phoneNumber = user.phoneNumber,
                            gender = user.gender,
                            moreInfo = user.moreInfo,
                            uri = user.uri
                        )
                        logMessage("outsideCurrentUserIs", currentUser.toString())
                    }
//                    logMessage("outsideCurrentUserIs", currentUser.toString())
                    MainBody(
                        UserInfo(
                            firstname="Emmanuel",
                            lastname="Agyapong",
                            email="[email protected]",
                            phoneNumber="9293038986",
                            gender="Male",
                            moreInfo="An incoming software engineer",
                            uri="https://firebasestorage.googleapis.com/v0/b/bookme-dc582.appspot.com/o/meAtBCC.jpg?alt=media&token=3d9b481c-9880-445f-939f-3b7bb60f3cbd"
                        ),
                        numberOfNotifications
                    )
                }
            }
        }
    }
}
private fun setUserInfo (callBack: (UserInfo) -> Unit) {
    val firebaseFirestoreInstance = FirebaseAuth.getInstance()
    val database: FirebaseFirestore = FirebaseFirestore.getInstance()
    database.collection("Users")
        .document(firebaseFirestoreInstance.uid.toString())
        .get()
        .addOnCompleteListener { task ->
            if (task.isSuccessful) {
                val u: UserInfo = UserInfo().copy(
                    firstname = task.result.data!!["firstname"].toString(),
                    lastname = task.result.data!!["lastname"].toString(),
                    email = task.result.data!!["email"].toString(),
                    phoneNumber = task.result.data!!["phone"].toString(),
                    gender = task.result.data!!["gender"].toString(),
                    moreInfo = task.result.data!!["moreInfo"].toString(),
                    uri = task.result.data!!["profileImage"].toString()
                )
                callBack(u)
            } else {
                Log.d(TAG, "Cached get failed: ", task.exception)
            }
        }

}

In java I could just do this:

private void getUserImageProfileUri() {
        firebasefirestore.collection("Users")
                .document(currentUserId)
                .get()
                .addOnSuccessListener(documentSnapshot -> {
                    userProfileImageURI = (String) documentSnapshot.get("userProfileImageURI");
                    username = (String) documentSnapshot.get("username");
                });
    }

I am an Android enthusiast so please understand that I am learning… thanks in advance!

I tried to rertieve data from a document on firebase, but I noticed that I could store the info in a variable only within the scope of .addOnCompleteListener{}, but after that the variable is empty as if I just initialized it. However, when I print the results inside of the adOnCompleteListener{}, I am able to see the values. How did I try to soleve the problem? Implemented different data structures and implemented callback, but nothing worked.