Flow with Room in Kotlin - kotlin

Question

i am new to kotlin android i am trying to use room with flow my code as follows
my entity as follows
#Entity(tableName = "user_data")
data class User (
#PrimaryKey(autoGenerate = true)
val id:Int,
val firstName:String,
val lastName:String,
val age:Int)
my database class as follows
#Database(entities = [User::class],version = 1,exportSchema = false)
abstract class UserDatabase :RoomDatabase(){
abstract fun userDao():UserDao
companion object{
#Volatile
private var INSTANCE:UserDatabase?=null
fun getDataBaseInstance(context:Context):UserDatabase
{
var tempInstance= INSTANCE
if(tempInstance!=null)
{
return tempInstance
}
synchronized(this)
{
val instance=Room.databaseBuilder(context.applicationContext,UserDatabase::class.java,"user_database")
.build()
INSTANCE=instance
return instance
}
}
}
}
my dao as follows
#Dao
interface UserDao {
#Insert(onConflict = OnConflictStrategy.IGNORE)
suspend fun addUser(user:User) :Long
#Query("SELECT * from user_data")
fun fetchUserData(): Flow<List<User>>
}
my repository as follows
class UserRepository(private val userDao:UserDao) {
suspend fun addUser(user:User){
val rowid:Long=userDao.addUser(user)
}
fun readAllUserData():Flow<List<User>>
{
val temp=userDao.fetchUserData()
return temp
}
}
my view model as follows
class UserViewModel(application: Context) :ViewModel() {
private lateinit var _readAllData:MutableLiveData<List<User>>
private var repository: UserRepository
private var _firstName:String="Akshay"
val firstName:String get()=_firstName
private var _lastName:String=""
val lastName:String get()=_lastName
private var _age:String = ""
val age:String get()=_age
val readAllData:LiveData<List<User>> get()=_readAllData
init {
val userDao= UserDatabase.getDataBaseInstance(application).userDao()
repository=UserRepository(userDao)
}
fun setFirstName(name:String)
{
_firstName=name
}
fun setLastName(name:String)
{
_lastName=name
}
fun setAge(name:String)
{
_age=name
}
fun addUserToDB()
{
viewModelScope.launch(Dispatchers.IO) {
println("Inside addUserDB")
repository.addUser(User(0,_firstName,_lastName,_age.toInt()))
}
}
fun readDataFromUserTable():LiveData<List<User>>
{
return repository.readAllUserData().asLiveData()
}
}
class UserViewModelFactory(private val context: Context):ViewModelProvider.Factory{
override fun <T : ViewModel?> create(modelClass: Class<T>): T {
if(modelClass.isAssignableFrom(UserViewModel::class.java))
{
return UserViewModel(context)as T
}
throw IllegalArgumentException("Unknown class")
}
my fragment as follows
class ListFragment : Fragment() {
private var binding:FragmentListBinding?=null
private val sharedViewModel:UserViewModel by activityViewModels {UserViewModelFactory(requireContext())}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val fragmentBinding=FragmentListBinding.inflate(inflater,container,false);
binding=fragmentBinding
return fragmentBinding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding?.apply {
viewModel=sharedViewModel
lifecycleOwner=viewLifecycleOwner
listFragment=this#ListFragment
ToastCount()
}
}
private fun ToastCount() {
var temp=sharedViewModel.readDataFromUserTable()
Toast.makeText(requireContext(), temp.size.toString(),Toast.LENGTH_SHORT).show()
}
fun addNewUser()
{ findNavController().navigate(R.id.action_listFragment_to_addFragment)
}
}
I can add data I see data in my database inspector but I can not read data it always return me null in my ViewModel ... I have added all necessary dependencies somebody please guild me what is it I am doing wrong? Thanks in advance