Develop Reference

Data From API Has Not Appeared Using Paging 3

I'm learning paging 3, but the data from the API doesn't appear. My code is like below:
interface PokeAPI {
#GET("pokemon")
fun getPokemonList() : Call<PokemonList>
#GET("pokemon")
fun getAllPokemon(
#Query("limit") limit: Int,
#Query("offset") offset: Int) : PokemonList
#GET("pokemon/{name}")
fun getPokemonInfo(
#Path("name") name: String
) : Call<Pokemon>
}
class PokePagingSource(private val apiService: PokeAPI): PagingSource<Int, Result>() {
private companion object {
const val INITIAL_PAGE_INDEX = 1
}
override suspend fun load(params: LoadParams<Int>): LoadResult<Int, Result> {
return try {
val position = params.key ?: INITIAL_PAGE_INDEX
val responseData = apiService.getAllPokemon(position, params.loadSize)
if (responseData.results.isEmpty()) {
Log.e("Response Succeed!", responseData.results.toString())
} else {
Log.e("Response Failed!", responseData.results.toString())
}
LoadResult.Page(
data = responseData.results,
prevKey = if (position == INITIAL_PAGE_INDEX) null else position - 1,
nextKey = if (responseData.results.isNullOrEmpty()) null else position + 1
)
} catch (exception: Exception) {
return LoadResult.Error(exception)
}
}
override fun getRefreshKey(state: PagingState<Int, Result>): Int? {
return state.anchorPosition?.let { anchorPosition ->
val anchorPage = state.closestPageToPosition(anchorPosition)
anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
}
}
}
class PokemonRepository(private val apiService: PokeAPI) {
fun getAllPokemon(): LiveData<PagingData<Result>>{
return Pager(
config = PagingConfig(
pageSize = 10
),
pagingSourceFactory = {
PokePagingSource(apiService)
}
).liveData
}
}
object Injection {
private val api by lazy { RetrofitClient().endpoint }
fun provideRepository(): PokemonRepository {
return PokemonRepository(api)
}
}
class PokemonViewModel(pokemonRepository: PokemonRepository) : ViewModel() {
val allPokemonList: LiveData<PagingData<Result>> =
pokemonRepository.getAllPokemon().cachedIn(viewModelScope)
}
class ViewModelFactory : ViewModelProvider.Factory {
override fun <T : ViewModel> create(modelClass: Class<T>): T {
if (modelClass.isAssignableFrom(PokemonViewModel::class.java)) {
#Suppress("UNCHECKED_CAST")
return PokemonViewModel(Injection.provideRepository()) as T
}
throw IllegalArgumentException("Unknown ViewModel class")
}
}
`class PokemonPagingAdapter(private val context: Context) :
PagingDataAdapter<Result, PokemonPagingAdapter.ViewHolder>(DIFF_CALLBACK) {
private var onItemClick: OnAdapterListener? = null
fun setOnItemClick(onItemClick: OnAdapterListener) {
this.onItemClick = onItemClick
}
class ViewHolder(val binding: AdapterPokemonBinding) : RecyclerView.ViewHolder(binding.root) {
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(
AdapterPokemonBinding.inflate(
LayoutInflater.from(parent.context),
parent,
false
)
)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val pokemonData = getItem(position)
if (pokemonData != null) {
holder.binding.apply {
val number = if (pokemonData.url.endsWith("/")) {
pokemonData.url.dropLast(1).takeLastWhile { it.isDigit() }
} else {
pokemonData.url.takeLastWhile { it.isDigit() }
}
val url = "https://raw.githubusercontent.com/PokeAPI/sprites/master/sprites/pokemon/${number}.png"
Glide.with(context)
.load(url)
.transition(DrawableTransitionOptions.withCrossFade())
.centerCrop()
.circleCrop()
.into(ivPokemon)
tvNamePokemon.text = pokemonData.name
btnDetail.setOnClickListener {
onItemClick?.onClick(pokemonData, pokemonData.name, url)
}
}
}
}
companion object {
val DIFF_CALLBACK = object : DiffUtil.ItemCallback<Result>() {
override fun areItemsTheSame(
oldItem: Result,
newItem: Result
): Boolean {
return oldItem == newItem
}
override fun areContentsTheSame(
oldItem: Result,
newItem: Result
): Boolean {
return oldItem.name == newItem.name
}
}
}
interface OnAdapterListener {
fun onClick(data: Result, name: String, url: String)
}
}`
class FragmentPokemon: Fragment(R.layout.fragment_pokemon) {
private var _binding : FragmentPokemonBinding? = null
private val binding get() = _binding!!
private lateinit var dataPagingAdapter: PokemonPagingAdapter
private val viewModel: PokemonViewModel by viewModels {
ViewModelFactory()
}
private lateinit var comm: Communicator
override fun onStart() {
super.onStart()
getData()
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
_binding = FragmentPokemonBinding.bind(view)
val toolBar = requireActivity().findViewById<View>(R.id.tool_bar)
toolBar.visibility = View.VISIBLE
val navBar = requireActivity().findViewById<BottomNavigationView>(R.id.bottom_navigation)
navBar.visibility = View.VISIBLE
comm = requireActivity() as Communicator
setupListPokemon()
}
private fun setupListPokemon(){
dataPagingAdapter = PokemonPagingAdapter(requireContext())
dataPagingAdapter.setOnItemClick(object: PokemonPagingAdapter.OnAdapterListener{
override fun onClick(data: Result, name: String, url: String) {
comm.passDataCom(name, url)
}
})
binding.apply {
rvPokemon.layoutManager = LinearLayoutManager(context)
rvPokemon.setHasFixedSize(true)
rvPokemon.adapter = dataPagingAdapter
}
}
private fun getData(){
viewModel.allPokemonList.observe(viewLifecycleOwner){
dataPagingAdapter.submitData(lifecycle, it)
binding.btnCoba.setOnClickListener { btn ->
if (it == null){
Log.e("ResponseFailed", it.toString())
} else Log.e("ResponseSucceed", it.toString())
}
}
}
}
What's the reason? I have followed the step by step implementation of paging 3 but the data still doesn't appear either.

I don't know the API you are using, but it seems that you are using it incorrectly. The getAllPokemon method has limit and offset parameters and you are calling it like apiService.getAllPokemon(position, params.loadSize), so you are using position as a limit and params.loadSize as an offset.
You should pass params.loadSize as a limit, rename INITIAL_PAGE_INDEX to INITIAL_OFFSET and set it to 0, since your API uses offsets instead of pages (at least it seems so from what you provided). The load function should then look something like this:
// get current offset
val offset = params.key ?: INITIAL_OFFSET
val responseData = apiService.getAllPokemon(limit = params.loadSize, offset = offset)
val prevKey = offset - params.loadSize
val nextKey = offset + params.loadSize

why returned flow in room is collecting for each of my SELECT after any changes in database(INSERT,UPDATE,DELETE) MVVM

I am using flow to get data after any changes in my room database ,my app is note and it use SELECT by searching and filter by priority [High,Normal,Low]. and it has delete and update and insert too. I get flows from model and in viewModel by search and filter I Collect my data from flows and post it to my single liveData and in the last I get them in my Observer in the view
my problem is after in SELECT when I use UPDATE or INSERTT or DELETE , all of my old SELECT(search and filter) repeat in the moment. it means if I search 1000 once, and use filter to my notes 99 once; I will collect 1099 flows in the moment again and my observer in the my view will be bombing!!!
My Dao:
#Dao
interface NoteDao {
#Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun saveNote(entity : NoteEntity)
#Delete
suspend fun deleteNote(note : NoteEntity)
#Update
suspend fun updateNote(note : NoteEntity)
#Query("SELECT * FROM $NOTE_TABLE")
fun getAllNotes() : Flow<MutableList<NoteEntity>>
#Query("SELECT * FROM $NOTE_TABLE WHERE id == :id")
fun getNote(id : Int) : Flow<NoteEntity>
#Query("SELECT * FROM $NOTE_TABLE WHERE priority == :priority")
fun fileNote(priority : String) : Flow<MutableList<NoteEntity>>
#Query("SELECT * FROM $NOTE_TABLE WHERE title LIKE '%' || :title || '%'")
fun searchNote(title : String) : Flow<MutableList<NoteEntity>>
}
My Repository:
class MainRepository #Inject constructor(private val dao : NoteDao) {
fun getAllNotes() = dao.getAllNotes()
fun getNotesByPriority(priority : String) = dao.fileNote(priority)
fun getNotesBySearch(title : String) = dao.searchNote(title)
suspend fun deleteNote(note: NoteEntity) = dao.deleteNote(note)
}
My ViewModel:
#HiltViewModel
class MainViewModel #Inject constructor(private val repository: MainRepository) : ViewModel() {
val notesData = object : MutableLiveData<DataStatus<MutableList<NoteEntity>>>(){
override fun postValue(value: DataStatus<MutableList<NoteEntity>>?) {
super.postValue(value)
Log.e("TAGJH", "postValue: ${value?.data?.size}")
}
}
fun getAllNotes() = viewModelScope.launch {
repository.getAllNotes().collect {
Log.e("TAGJH", "getAll: ${it.size}")
notesData.postValue(DataStatus.success(it, it.isEmpty()))
}
}
fun getNoteByPriority(priority: String) = viewModelScope.launch {
repository.getNotesByPriority(priority).collect {
Log.e("TAGJH", "priority ${it.size }->$priority")
notesData.postValue(DataStatus.success(it, it.isEmpty()))
}
}
fun getNoteBySearch(characters: String) = viewModelScope.launch {
repository.getNotesBySearch(characters).collect {
Log.e("TAGJH", "collect: ${it.size}")
notesData.postValue(DataStatus.success(it, it.isEmpty()))
}
}
fun deleteNote(note: NoteEntity) = viewModelScope.launch {
repository.deleteNote(note)
}
}
My View:
#AndroidEntryPoint
class MainActivity : AppCompatActivity() {
private var selectedItem: Int = 0
private var _binding: ActivityMainBinding? = null
private val binding get() = _binding
#Inject
lateinit var noteAdapter: NoteAdapter
#Inject
lateinit var noteEntity: NoteEntity
private val viewModel: MainViewModel by viewModels()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
_binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding?.root)
binding?.apply {
setSupportActionBar(notesToolbar)
addNoteBtn.setOnClickListener {
NoteFragment().show(supportFragmentManager, NoteFragment().tag)
}
viewModel.notesData.observe(this#MainActivity) {
showEmpty(it.isEmpty)
noteAdapter.setData(it.data!!)
noteList.apply {
layoutManager =
StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL)
adapter = noteAdapter
}
}
viewModel.getAllNotes()
notesToolbar.setOnMenuItemClickListener {
when (it.itemId) {
R.id.actionFilter -> {
filterByProperty()
return#setOnMenuItemClickListener true
}
else -> return#setOnMenuItemClickListener false
}
}
deleteAndUpdateListener()
}
}
private fun deleteAndUpdateListener() =
noteAdapter.onItemClickListener { note, title ->
when (title) {
DELETE -> {
noteEntity.id = note.id
noteEntity.title = note.title
noteEntity.des = note.des
noteEntity.priority = note.priority
noteEntity.category = note.category
viewModel.deleteNote(noteEntity)
}
EDIT -> {
val noteFragment = NoteFragment()
val bundle = Bundle()
bundle.putInt(BUNDLE_ID, note.id)
noteFragment.arguments = bundle
noteFragment.show(supportFragmentManager, NoteFragment().tag)
}
}
}
private fun showEmpty(isShown: Boolean) {
binding?.apply {
if (isShown) {
emptyShowing.visibility = View.VISIBLE
noteList.visibility = View.GONE
} else {
emptyShowing.visibility = View.GONE
noteList.visibility = View.VISIBLE
}
}
}
override fun onDestroy() {
super.onDestroy()
_binding = null
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
menuInflater.inflate(R.menu.menu_toolbar, menu)
val search = menu.findItem(R.id.actionSearch)
val searchView = search.actionView as SearchView
searchView.queryHint = getString(R.string.search)
searchView.setOnQueryTextListener(object : SearchView.OnQueryTextListener {
override fun onQueryTextSubmit(query: String?): Boolean {
return false
}
override fun onQueryTextChange(newText: String): Boolean {
viewModel.getNoteBySearch(newText)
Log.e("TAGJH", "searching")
return true
}
})
return super.onCreateOptionsMenu(menu)
}
private fun filterByProperty() {
val builder = AlertDialog.Builder(this)
val priories = arrayOf(ALL, HIGH, NORMAL, LOW)
builder.setSingleChoiceItems(priories, selectedItem) { dialog, item ->
when (item) {
0 -> {
viewModel.getAllNotes()
}
in 1..3 -> {
viewModel.getNoteByPriority(priories[item])
}
}
selectedItem = item
dialog.dismiss()
}
val dialog: AlertDialog = builder.create()
dialog.show()
}
}
I want to see my note after any update or delete or insert is updating in my last SELECT from room database

RecyclerView doesn't appear in a Fragment

Why doesn't RecyclerView appear in my fragment? I've added recyclerview adapter in the fragment, but it still didn't appear. Here are the codes:
FollowersFragment.kt
class FollowersFragment : Fragment() {
private lateinit var binding: FragmentFollowersBinding
companion object {
private const val TAG = "FollowersFragment"
const val ARG_NAME = "userName"
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_followers, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding = FragmentFollowersBinding.inflate(layoutInflater)
val username = arguments?.getString(ARG_NAME)
val layoutManager = LinearLayoutManager(requireActivity())
binding.rvFollowers.layoutManager = layoutManager
val itemDecoration = DividerItemDecoration(requireActivity(), layoutManager.orientation)
binding.rvFollowers.addItemDecoration(itemDecoration)
val client = ApiConfig.getApiService().getFollowers(username.toString(),"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")
client.enqueue(object : Callback<List<FollowsResponseItem>> {
override fun onResponse(
call: Call<List<FollowsResponseItem>>,
response: Response<List<FollowsResponseItem>>
) {
if(response.isSuccessful){
val responseBody = response.body()
if(responseBody!=null){
Log.d(TAG,responseBody.toString())
setUserData(responseBody)
}else{
Log.e(TAG,"onFailure: ${response.message()}")
}
}
}
override fun onFailure(call: Call<List<FollowsResponseItem>>, t: Throwable) {
Log.e(TAG, "onFailure: ${t.message}")
}
})
}
fun setUserData(item: List<FollowsResponseItem>){
val listUser = ArrayList<UserResponse>()
val executor = Executors.newSingleThreadExecutor()
executor.execute {
try {
for (i in 0..item.size-1) {
if(item.size>5 && i>5){
break
}
val client = ApiConfig.getApiService()
.getUser(item.get(i).login, "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")
client.enqueue(object : Callback<UserResponse> {
override fun onResponse(
call: Call<UserResponse>,
response: Response<UserResponse>
) {
if (response.isSuccessful) {
val responseBody = response.body()
if (responseBody != null) {
listUser.add(responseBody)
if(i==4 || item.get(i).login.equals(item.get(item.size-1).login)){
Log.d(TAG,"user : $listUser")
val adapter = ListUserAdapter(listUser)
binding.rvFollowers.adapter = adapter
Log.d(TAG,adapter.toString())
adapter.setOnItemClickCallback(object: ListUserAdapter.OnItemClickCallback{
override fun onItemClicked(data: UserParcelable) {
showSelectedUser(data)
}
})
}
} else {
Log.e(TAG, "onFailure: ${response.message()}")
}
}
}
override fun onFailure(call: Call<UserResponse>, t: Throwable) {
Log.e(TAG, "onFailure: ${t.message}")
}
})
}
} catch(e: InterruptedException) {
e.printStackTrace()
}
}
}
private fun showSelectedUser(data: UserParcelable) {
}
}
DetailActivity.kt
class DetailActivity : AppCompatActivity() {
private lateinit var binding: ActivityDetailBinding
private var getUserName: String ="sidiqpermana"
companion object{
const val EXTRA_DATA = "extra_data"
#StringRes
private val TAB_TITLES = intArrayOf(
R.string.tab_text_1,
R.string.tab_text_2
)
}
#SuppressLint("SetTextI18n")
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
supportActionBar?.hide()
binding = ActivityDetailBinding.inflate(layoutInflater)
setContentView(binding.root)
val data = intent.getParcelableExtra<UserParcelable>(EXTRA_DATA) as UserParcelable
val sectionsPagerAdapter = SectionsPagerAdapter(this)
val viewPager: ViewPager2 = binding.viewPager
viewPager.adapter = sectionsPagerAdapter
val tabs: TabLayout = binding.tabs
sectionsPagerAdapter.userName = data.login
TabLayoutMediator(tabs,viewPager){ tab, position ->
tab.text = resources.getString(TAB_TITLES[position])
}.attach()
getUserName = data.login
showInfo(data)
}
fun getUserName() : String{
return getUserName
}
#SuppressLint("SetTextI18n")
private fun showInfo(data: UserParcelable){
Glide.with(this#DetailActivity)
.load(data.avatar_url)
.into(binding.detailPp)
if(data.name.equals("null")) binding.detailName.setText("No Name") else binding.detailName.setText(data.name)
binding.detailUsername.setText(data.login)
if(data.bio.equals("null")) binding.detailBio.setText("No Name") else binding.detailBio.setText(data.bio)
binding.detailFollowers.setText("${data.followers} Followers")
binding.detailFollowings.setText("${data.following} Following")
if(data.location.equals("null")) binding.detailLocation.setText("No Location") else binding.detailLocation.setText(data.location)
}
}
ListUserAdapter.kt (RecyclerView Adapter)
class ListUserAdapter (private val listUser: ArrayList<UserResponse>) : RecyclerView.Adapter<ListUserAdapter.ListViewHolder>() {
private lateinit var onItemClickCallback: OnItemClickCallback
fun setOnItemClickCallback(onItemClickCallback: OnItemClickCallback){
this.onItemClickCallback = onItemClickCallback
}
class ListViewHolder(var binding: ItemUsersRowBinding) : RecyclerView.ViewHolder(binding.root) {
}
override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): ListViewHolder {
val binding = ItemUsersRowBinding.inflate(LayoutInflater.from(viewGroup.context),viewGroup,false)
return ListViewHolder(binding)
}
#SuppressLint("SetTextI18n")
override fun onBindViewHolder(holder: ListViewHolder, position: Int) {
var (followers,avatar_url,following, name,bio, location, login) = listUser[position]
name = name ?: "No Name"
bio = bio ?: "No Bio"
location = location?: "No Location"
holder.apply {
Glide.with(itemView.getContext())
.load(avatar_url)
.into(binding.photoProfile)
binding.profileName.setText(name.toString())
binding.username.setText(login)
binding.followers.setText("$following Followers")
binding.followings.setText("$following Followings")
binding.location.setText(location.toString())
val detailUser = UserParcelable(followers,avatar_url,following,
name.toString(), bio.toString(), location.toString(), login)
itemView.setOnClickListener{ onItemClickCallback.onItemClicked(detailUser)}
}
}
override fun getItemCount(): Int {
return listUser.size
}
interface OnItemClickCallback {
fun onItemClicked(data: UserParcelable)
}
}
Help me solve this problem please.

There is no need to initialize adapter every time you want to update the list. Either make your ListUserAdapter extend ListAdapter and than use adapter.submitList(listUser) or if you want to extend RecyclerView.Adapter as you do, you can do the following :
class ListUserAdapter () : RecyclerView.Adapter<ListUserAdapter.ListViewHolder>() {
private val listUser: List<UserResponse>
fun submitList(newList: List<UserResponse>) {
listUser = newList
notifyDataSetChanged()
}
override fun onBindViewHolder(holder: ListViewHolder, position: Int) {
val listItem = listUser[position]
...
}
override fun getItemCount(): Int {
return listUser.size
}
}
I suggest you go with ListAdapter. Check if Log.d(TAG,"user : $listUser") is printed, if it is and listUser is not empty than call adapter.submitList(listUser) and RV should be populated.

You have missed to notify adapter about the changes, So after
binding.rvFollowers.adapter = adapter call adapter.notifyDataSetChanged()

How can I handle the state value on change without using Composable in Kotlin?

I have a VM and a fragment. I want to handle the change of state.value in the fragment. How can I do that. Here is the fragment:
AndroidEntryPoint
class ImportFragment : Fragment() {
private val importVM by viewModels<ImportFragmentVM>()
lateinit var importButton: Button
lateinit var createButton: Button
lateinit var tab: TabLayout
lateinit var createItems: Group
lateinit var importItems: Group
lateinit var longUrl: EditText
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val view = inflater.inflate(R.layout.import_fragment, container, false)
importButton = view.findViewById(R.id.importButton)
createButton = view.findViewById(R.id.createButton)
tab = view.findViewById(R.id.tab)
createItems = view.findViewById(R.id.createGroup)
importItems = view.findViewById(R.id.importGroup)
longUrl = view.findViewById(R.id.longurl)
createItems.isVisible = false
Timber.d("tab position:" + tab.selectedTabPosition)
tab.addOnTabSelectedListener(object : TabLayout.OnTabSelectedListener {
override fun onTabSelected(tab: TabLayout.Tab) {
when (tab.position) {
0 -> {
createItems.isVisible = false
importItems.isVisible = true
Timber.d("position 0")
}
1 -> {
createItems.isVisible = true
importItems.isVisible = false
Timber.d("position 1")
}
}
}
override fun onTabUnselected(tab: TabLayout.Tab?) {
}
override fun onTabReselected(tab: TabLayout.Tab?) {
}
})
longUrl.addTextChangedListener(object : TextWatcher {
override fun afterTextChanged(s: Editable) {}
override fun beforeTextChanged(
s: CharSequence, start: Int,
count: Int, after: Int
) {
}
override fun onTextChanged(
s: CharSequence, start: Int,
before: Int, count: Int
) {
importVM.updateInput(longUrl.text.toString())
}
})
createButton.setOnClickListener {
val x = importVM.submit()
if (x is ImportFragmentVM.ImportUIState.Success)
Timber.d("assadads")
}
return view
}
}
And here is the VM for this fragment:
#HiltViewModel
class ImportFragmentVM #Inject constructor(
private val service: UrlService
) : ViewModel() {
sealed interface ImportUIState {
data class PendingUserInput(val longUrl: String) : ImportUIState
object Loading : ImportUIState
object Success : ImportUIState
data class PartialSuccess(val urlKey: UrlKey, val urlApiKey: UrlApiKey) : ImportUIState
object Error : ImportUIState
object Invalid : ImportUIState
}
val _state = MutableStateFlow<ImportUIState>(PendingUserInput(""))
val state: StateFlow<ImportUIState> = _state
fun updateInput(longUrl: String) {
check(_state.value is PendingUserInput) { "You can't be in update" }
Timber.d("longurl:" + longUrl)
_state.value = PendingUserInput(longUrl)
}
fun submit():ImportUIState {
val longUrl = state.value.run {
check(this is PendingUserInput) { "You can't be in update when submitting" }
longUrl
}
Timber.d("sunt in submit")
_state.value = Loading
Timber.d("value is" + state.value)
viewModelScope.launch(Dispatchers.IO) {
val result = service.shortenUrl(longUrl)
if (result is ShortenRequestOutcome.Failed)
_state.value = Error
if (result is ShortenRequestOutcome.Invalid)
_state.value = Invalid
if (result is ShortenRequestOutcome.Success)
_state.value = Success
}
return state.value
}
}
For example I want to show a dialog/toast based on the state.value, and I don't know how to find out in the fragment when the value has changed. Any ideas?

To collect your flow in a Fragment, you can use:
viewLifecycleOwner.lifecycleScope.launch {
viewLifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) {
importVM.state.collect { data ->
//do something
}
}
}

Paging 3 Library calls the load method recursively with LoadType.APPEND

I am trying to display data from IconFinder API. It seems to be ItemKeyedDataSource for me and I used Paging3 to display the data as it's mentioned in the official docs.
Here is code, please check if there're any issues with the implementation I have done and where is the mistake.
IconSetsRemoteMediator
#OptIn(ExperimentalPagingApi::class)
class IconSetsRemoteMediator(
private val query: String?,
private val database: IconsFinderDatabase,
private val networkService: IconFinderAPIService
) : RemoteMediator<Int, IconSetsEntry>() {
private val TAG: String? = IconSetsRemoteMediator::class.simpleName
private val iconSetsDao = database.iconSetsDao
private val remoteKeysDao = database.remoteKeysDao
override suspend fun initialize(): InitializeAction {
// Load fresh data when ever the app is open new
return InitializeAction.LAUNCH_INITIAL_REFRESH
}
override suspend fun load(
loadType: LoadType,
state: PagingState<Int, IconSetsEntry>
): MediatorResult {
val iconSetID = when (loadType) {
LoadType.REFRESH -> {
null
}
LoadType.PREPEND -> {
return MediatorResult.Success(
endOfPaginationReached = true
)
}
LoadType.APPEND -> {
Log.d(TAG, "LoadType.APPEND")
val lastItem = state.lastItemOrNull()
if (lastItem == null) {
return MediatorResult.Success(
endOfPaginationReached = true
)
}
// Get the last item from the icon-sets list and return its ID
lastItem.iconset_id
}
}
try {
// Suspending network load via Retrofit.
val response = networkService.getAllPublicIconSets(after = iconSetID)
val iconSets = response.iconsets
val endOfPaginationReached = iconSets == null || iconSets.isEmpty()
database.withTransaction {
if (loadType == LoadType.REFRESH) {
// Delete the data in the database
iconSetsDao.deleteAllIconSets()
//remoteKeysDao.deleteRemoteKeys()
}
Log.d(TAG, "iconSets = ${iconSets?.size}")
Log.d(TAG, "endOfPaginationReached = $endOfPaginationReached")
Log.d(TAG, "state.anchorPosition = ${state.anchorPosition}")
Log.d(TAG, "state.pages = ${state.pages.size}")
val time = System.currentTimeMillis()
/*val remoteKeys = iconSets!!.map {
RemoteKeysEntry(it.iconset_id, time)
}*/
// Insert new IconSets data into database, which invalidates the current PagingData,
// allowing Paging to present the updates in the DB.
val data = iconSets!!.mapAsIconSetsEntry()
iconSetsDao.insertAllIconSets(data)
// Insert the remote key values which set the time at which the data is
// getting updated in the DB
//remoteKeysDao.insertRemoteKeys(remoteKeys)
}
return MediatorResult.Success(endOfPaginationReached = endOfPaginationReached)
} catch (exception: IOException) {
return MediatorResult.Error(exception)
} catch (exception: HttpException) {
return MediatorResult.Error(exception)
}
}
}
IconFinderRepository
class IconFinderRepository(
private val service: IconFinderAPIService,
private val database: IconsFinderDatabase
) {
private val TAG: String? = IconFinderRepository::class.simpleName
fun getPublicIconSets(): Flow<PagingData<IconSetsEntry>> {
Log.d(TAG, "New Icon Sets query")
val pagingSourceFactory = { database.iconSetsDao.getIconSets() }
#OptIn(ExperimentalPagingApi::class)
return Pager(
config = PagingConfig(pageSize = NUMBER_OF_ITEMS_TO_FETCH, enablePlaceholders = false),
remoteMediator = IconSetsRemoteMediator(
query = null,
database,
service
),
pagingSourceFactory = pagingSourceFactory
).flow
}
companion object {
const val NUMBER_OF_ITEMS_TO_FETCH = 20
}
}
IconSetViewHolder
class IconSetViewHolder private constructor(val binding: RecyclerItemIconSetBinding) :
RecyclerView.ViewHolder(binding.root) {
fun bind(iconSetsEntry: IconSetsEntry?) {
if (iconSetsEntry == null) {
//Show the Loading UI
} else {
binding.model = iconSetsEntry
binding.executePendingBindings()
}
}
companion object {
fun from(parent: ViewGroup): IconSetViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val binding = RecyclerItemIconSetBinding.inflate(layoutInflater, parent, false)
return IconSetViewHolder(binding)
}
}
}
IconSetAdapter
class IconSetAdapter : PagingDataAdapter<UiModel.IconSetDataItem, ViewHolder>(UI_MODEL_COMPARATOR) {
companion object {
private val UI_MODEL_COMPARATOR =
object : DiffUtil.ItemCallback<UiModel.IconSetDataItem>() {
override fun areContentsTheSame(
oldItem: UiModel.IconSetDataItem,
newItem: UiModel.IconSetDataItem
): Boolean {
return oldItem.iconSetsEntry.iconset_id == newItem.iconSetsEntry.iconset_id
}
override fun areItemsTheSame(
oldItem: UiModel.IconSetDataItem,
newItem: UiModel.IconSetDataItem
): Boolean =
oldItem == newItem
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return if (viewType == R.layout.recycler_item_icon_set) {
IconSetViewHolder.from(parent)
} else {
IconSetViewHolder.from(parent)
}
}
override fun getItemViewType(position: Int): Int {
return when (getItem(position)) {
is UiModel.IconSetDataItem -> R.layout.recycler_item_icon_set
null -> throw UnsupportedOperationException("Unknown view")
else -> throw UnsupportedOperationException("Unknown view")
}
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val uiModel = getItem(position)
uiModel.let {
when (uiModel) {
is UiModel.IconSetDataItem -> (holder as IconSetViewHolder).bind(uiModel.iconSetsEntry)
}
}
}
}
HomeFragmentViewModel
class HomeFragmentViewModel(application: Application) : AndroidViewModel(application) {
private val TAG: String? = HomeFragmentViewModel::class.simpleName
private val repository: IconFinderRepository = IconFinderRepository(
IconFinderAPIService.create(),
IconsFinderDatabase.getInstance(application)
)
private var iconSetsQueryResult: Flow<PagingData<UiModel.IconSetDataItem>>? = null
fun iconSetsQuery(): Flow<PagingData<UiModel.IconSetDataItem>> {
val newResult: Flow<PagingData<UiModel.IconSetDataItem>> = repository.getPublicIconSets()
.map { pagingData -> pagingData.map { UiModel.IconSetDataItem(it) } }
.cachedIn(viewModelScope)
iconSetsQueryResult = newResult
return newResult
}
/**
* Factory for constructing HomeFragmentViewModel
*/
class Factory(private val application: Application) : ViewModelProvider.Factory {
override fun <T : ViewModel?> create(modelClass: Class<T>): T {
if (modelClass.isAssignableFrom(HomeFragmentViewModel::class.java)) {
return HomeFragmentViewModel(application) as T
}
throw IllegalArgumentException("Unable to construct ViewModel")
}
}
}
sealed class UiModel {
data class IconSetDataItem(val iconSetsEntry: IconSetsEntry) : UiModel()
}
IconSetFragment: This is one of the fragments implemented as part of ViewPager. Its parent is a Fragment in an Activity.
class IconSetFragment : Fragment() {
private val TAG: String = IconSetFragment::class.java.simpleName
/**
* Declaring the UI Components
*/
private lateinit var binding: FragmentIconSetBinding
private val viewModel: HomeFragmentViewModel by viewModels()
private val adapter = IconSetAdapter()
private var job: Job? = null
companion object {
fun newInstance(): IconSetFragment {
return IconSetFragment()
}
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Get a reference to the binding object
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_icon_set, container, false)
Log.d(TAG, "onCreateView")
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
initAdapter()
job?.cancel()
job = viewLifecycleOwner.lifecycleScope.launch {
viewModel.iconSetsQuery().collectLatest {
adapter.submitData(it)
Log.d(TAG, "collectLatest $it")
}
}
}
private fun initAdapter() {
binding.rvIconSetList.adapter = adapter
/*.withLoadStateHeaderAndFooter(
header = LoadStateAdapter(), // { adapter.retry() },
footer = LoadStateAdapter { adapter.retry() }
)*/
}
}
IconSetsDao
#Dao
interface IconSetsDao {
#Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun insertAllIconSets(iconSets: List<IconSetsEntry>)
#Query("SELECT * FROM icon_sets_table")
fun getIconSets(): PagingSource<Int, IconSetsEntry>
#Query("DELETE FROM icon_sets_table")
suspend fun deleteAllIconSets()
}
This is the Logcat screenshot, the load() method is being invoked without any scrolling action.

I have the similar issue, seems the recursive loading issue is fixed by setting the recyclerView.setHasFixedSize(true)