JetpackCompose Fragment onCreate issue - android-fragments

Question

I need to call a function in my SignScreen's onCreate method but there is not any applicable place for this. I can't call currentUserCheck function from anywhere.
What i tried :
Calling it in init block in viewModel. But the problem was it throwing nullPointerException for NavController here.
Calling it in MainActivity and MyTheme but i faced many weird issues in these scopes.
ViewModel:
#HiltViewModel
class SignViewModel (#ApplicationContext context: Context) : ViewModel() {
val auth = FirebaseAuth.getInstance()
init {
currentUserCheck(NavController(context))
}
fun signIn(email: String?, password: String?, context: Context, navController: NavController) {
if (email != null && email.isNotBlank() && password != null && password.isNotBlank()) {
auth.signInWithEmailAndPassword(email, password).addOnSuccessListener {
navController.navigate(ScreenHolder.ProfileScreen.route) {
popUpTo(ScreenHolder.SigningScreen.route) {
inclusive = true
}
}
}.addOnFailureListener {
Toast.makeText(context, it.localizedMessage, Toast.LENGTH_LONG).show()
}
} else {
Toast.makeText(
context,
"Lütfen email ve şifre alanlarını boş bırakmayınız.",
Toast.LENGTH_LONG
).show()
}
}
fun signUp(email: String?, password: String?, context: Context, navController: NavController) {
if (email != null && email.isNotBlank() && password != null && password.isNotBlank()) {
auth.createUserWithEmailAndPassword(email, password)
.addOnSuccessListener {
navController.navigate(ScreenHolder.ProfileScreen.route) {
popUpTo(ScreenHolder.ProfileScreen.route) {
inclusive = true
}
}
}
} else {
Toast.makeText(
context,
"Lütfen email ve şifre alanlarını boş bırakmayınız.",
Toast.LENGTH_LONG
).show()
}
}
fun currentUserCheck(navController: NavController) {
if (auth.currentUser != null) {
navController.navigate(ScreenHolder.ProfileScreen.route) {
popUpTo(ScreenHolder.ProfileScreen.route) {
inclusive = true
}
}
}
}
}

Answer 1

Solution
As #Pztar said i declare the authentication controlling operation as a state in viewModel and then i observed it in my Composable SignScreen with LaunchEffect and it is solved.
#HiltViewModel
class SignViewModel (#ApplicationContext context: Context) : ViewModel() {
val auth = FirebaseAuth.getInstance()
var currentUser = mutableStateOf(false)
//New currenUserCheck method that declare if state is true or not
fun currentUserCheck() {
if (auth.currentUser != null) {
currentUser.value = true
}
}
}
#Composable
fun SignScreen(viewModel: SignViewModel= hiltViewModel(),navController: NavController,context: Context) {
//Observing the state from my composable and routing user if state is true.
LaunchedEffect(key1 = Unit ){
viewModel.currentUserCheck()
if (viewModel.currentUser.value){
navController.navigate(ScreenHolder.ProfileScreen.route) {
popUpTo(ScreenHolder.SigningScreen.route) {
inclusive = true
}
}
}
}
}