Android ViewModel in PreferenceFragmentCompat - android

This is my first jetpack app with android and kotlin, so I'm fairly unexperienced.
Following the Google's guideline on how to manage data, I created a viewmodel which downloads from my api some data.
Now I need to show that data inside a ListPreference inside a PreferenceFragmentCompat class:
override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
setPreferencesFromResource(R.xml.texts, rootKey)
this.language = findPreference("language")
homeViewModel.languagesAndPropers.observe(viewLifecycleOwner, this.observer)
}
the method observe(...) is not firing, so its callback (this.observer in my case) never run.
Edit:
this is the observer detail
private val observer = Observer<Result<Item>> {
when (it.status) {
Status.LOADING -> > Toast.makeText(context, "loading", Toast.LENGTH_LONG).show()
Status.ERROR -> Toast.makeText(context, it.error!!.message, Toast.LENGTH_LONG).show()
Status.SUCCESS -> {
// do something with the data
}
}
}
Edit 2: here's the definition for languageandpropers
class HomeViewModel(private val repo: LanguagesAndPropersRepository) : ViewModel() {
private val _lp = MediatorLiveData<Resource<LanguagesAndPropers>>()
private var lpSource: LiveData<Resource<LanguagesAndPropers>> = MutableLiveData()
val languagesAndPropers: LiveData<Resource<LanguagesAndPropers>> get() = _lp
init {
getLP(false)
}
fun refresh() {
getLP(true)
}
private fun getLP(forceRefresh: Boolean) = viewModelScope.launch(Dispatchers.Main) {
_lp.removeSource(lpSource) // We make sure there is only one source of live data (allowing us properly refresh)
withContext(Dispatchers.IO) { lpSource = repo.getLanguagesAndPropers(forceRefresh) }
_lp.addSource(lpSource) {
_lp.value = it
}
}
}
I dunno what's missing in my code.

i know its late but maybe useful for others
use your
viewModel inside onViewCreated
override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
setPreferencesFromResource(R.xml.texts, rootKey)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val language : Preference? = findPreference("language")
homeViewModel.languagesAndPropers.observe(viewLifecycleOwner, {
// do something with languagesAndPropers value
})
}

Related

Combining Two Flows and add them to temporary list of StateFlow(Hot Flows)

I m getting data from two End points using flows and assigning those two list to temporary list in ViewModel. For this purpose, I'm using combine function and returning result as stateFlows with stateIn operator but that's not working. Can anyone point me out where I go wrong please.
ViewModel.kt
private val _movieItem: MutableStateFlow<State<List<HomeRecyclerViewItems>>> =
MutableStateFlow(State.Loading())
val movieItems: StateFlow<State<List<HomeRecyclerViewItems>>> = _movieItem
fun getHomeItemList() {
viewModelScope.launch {
val testList: Flow<State<List<HomeRecyclerViewItems.Movie>>> =
settingsRepo.getMovieList().map {
State.fromResource(it)
}
val directorList: Flow<State<List<HomeRecyclerViewItems.Directors>>> =
settingsRepo.getDirectorList().map {
State.fromResource(it)
}
_movieItem.value = combine(testList, directorList) { testList, directorList ->
testList + directorList // This is not working as "+" Unresolve Error
}.stateIn(
viewModelScope,
SharingStarted.WhileSubscribed(5000),
State.loading<Nothing>()
) as State<List<HomeRecyclerViewItems>> // Unchecked cast: StateFlow<Any> to State<List<HomeRecyclerViewItems>>
}
Repository.kt
fun getMovieList(): Flow<ResponseAPI<List<HomeRecyclerViewItems.Movie>>> {
return object :
NetworkBoundRepository<List<HomeRecyclerViewItems.Movie>, List<HomeRecyclerViewItems.Movie>>() {
override suspend fun saveRemoteData(response: List<HomeRecyclerViewItems.Movie>) {
}
override fun fetchFromLocal() {
}
override suspend fun fetchFromRemote(): Response<List<HomeRecyclerViewItems.Movie>> =
apiInterface.getMoviesList()
}.asFlow()
}
fun getDirectorList(): Flow<ResponseAPI<List<HomeRecyclerViewItems.Directors>>> {
return object :
NetworkBoundRepository<List<HomeRecyclerViewItems.Directors>, List<HomeRecyclerViewItems.Directors>>() {
override suspend fun saveRemoteData(response: List<HomeRecyclerViewItems.Directors>) {
}
override fun fetchFromLocal() {
}
override suspend fun fetchFromRemote(): Response<List<HomeRecyclerViewItems.Directors>> =
apiInterface.getDirectorsList()
}.asFlow()
}
Network BoundRepository.kt
#ExperimentalCoroutinesApi
abstract class NetworkBoundRepository<RESULT, REQUEST> {
fun asFlow() = flow<ResponseAPI<REQUEST>> {
val apiResponse = fetchFromRemote()
val remotePosts = apiResponse.body()
if (apiResponse.isSuccessful && remotePosts != null) {
emit(ResponseAPI.Success(remotePosts))
} else {
emit(ResponseAPI.Failed(apiResponse.errorBody()!!.string()))
}
}.catch { e ->
e.printStackTrace()
emit(ResponseAPI.Failed("Server Problem! Please try again Later. "))
}
#WorkerThread
protected abstract suspend fun saveRemoteData(response: REQUEST)
#MainThread
protected abstract fun fetchFromLocal()
#MainThread
protected abstract suspend fun fetchFromRemote(): Response<REQUEST>
}
Endpoints with Sealed Class
#GET("directors")
fun getDirectorsList(): Response<List<HomeRecyclerViewItems.Directors>>
#GET("movies")
fun getMoviesList(): Response<List<HomeRecyclerViewItems.Movie>>
sealed class HomeRecyclerViewItems {
class Title(
val id: Int,
val title: String
) : HomeRecyclerViewItems()
class Movie(
val id: Int,
val title: String,
val thumbnail: String,
val releaseDate: String
) : HomeRecyclerViewItems()
class Directors(
val id: Int,
val name: String,
val avator: String,
val movie_count: Int
) : HomeRecyclerViewItems()
}
Fragment.kt
#AndroidEntryPoint
#ExperimentalCoroutinesApi
class SettingsFragment : BaseBottomTabFragment() {
private var _binding: FragmentSettingsBinding? = null
private val binding get() = _binding!!
private val viewModel by viewModels<SettingViewModel>()
#Inject
lateinit var recyclerViewAdapter: RecyclerViewAdapter
#Inject
lateinit var bundle: Bundle
var finalList = mutableListOf<HomeRecyclerViewItems>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
// Inflate the layout for this fragment
_binding = FragmentSettingsBinding.inflate(layoutInflater,container,false)
val view = binding.root
binding.rvMovie.apply {
setHasFixedSize(true)
layoutManager = LinearLayoutManager(activity)
}
bundle.putString("Hello","hihg")
Toast.makeText(activity, "${bundle.getString("Hello")}", Toast.LENGTH_SHORT).show()
finalList.add(HomeRecyclerViewItems.Title(1,"hello"))
return view
}
private fun observeList() {
viewLifecycleOwner.lifecycleScope.launch {
viewLifecycleOwner.lifecycle.repeatOnLifecycle(Lifecycle.State.STARTED){
launch {
viewModel.movieItems.collect { state ->
when(state){
is State.Loading ->{
}
is State.Success->{
if (state.data.isNotEmpty()){
recyclerViewAdapter = RecyclerViewAdapter()
binding.rvMovie.adapter = recyclerViewAdapter
recyclerViewAdapter.submitList(finalList)
}
}
is State.Error -> {
Toast.makeText(activity, "Error", Toast.LENGTH_SHORT).show()
}
else -> Unit
}
}
}
}
}
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
(activity as MainActivity).binding.ivSearch.isGone = true
viewModel.getHomeItemList()
observeList()
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
}
Note: I m following this tutorial simpliedCoding for api data for multirecyclerview but want to implement it with Kotlin State Flow. Any help in this regard is highly appreciated. Thanks.
Your problem is in here
val testList: Flow<State<List<HomeRecyclerViewItems.Movie>>> =
settingsRepo.getMovieList().map {
State.fromResource(it)
}
val directorList: Flow<State<List<HomeRecyclerViewItems.Directors>>> =
settingsRepo.getDirectorList().map {
State.fromResource(it)
}
_movieItem.value = combine(testList, directorList) { testList, directorList ->
testList + directorList
}
They are not returning a List<HomeRecyclerViewItems>, but a State<List<HomeRecyclerViewItems>. Maybe a better name for the variables are testsState and directorsState. After that it will be more clear why you need to unpack the values before combining the lists
_movieItem.value = combine(testsState, directorsState) { testsState, directorsState ->
val homeRecyclerViewItems = mutableListOf<HomeRecyclerViewItems>()
if (testsState is Success) homeRecyclerViewItems.add(testsState.data)
if (directorsState is Success) homeRecyclerViewItems.add(directorsState.data)
homeRecyclerViewItems
}

Firestore with StateFlow real time change is observed in repo and view model, but adapter is not being updated

As a developer one needs to adapt to change, I read somewhere it says:
If you don’t choose the right architecture for your Android project, you will have a hard time maintaining it as your codebase grows and your team expands.
I wanted to implement Clean Architecture with MVVM
My app data flow will look like this:
Model class
data class Note(
val title: String? = null,
val timestamp: String? = null
)
Dtos
data class NoteRequest(
val title: String? = null,
val timestamp: String? = null
)
and
data class NoteResponse(
val id: String? = null,
val title: String? = null,
val timestamp: String? = null
)
Repository layer is
interface INoteRepository {
fun getNoteListSuccessListener(success: (List<NoteResponse>) -> Unit)
fun deleteNoteSuccessListener(success: (List<NoteResponse>) -> Unit)
fun getNoteList()
fun deleteNoteById(noteId: String)
}
NoteRepositoryImpl is:
class NoteRepositoryImpl: INoteRepository {
private val mFirebaseFirestore = Firebase.firestore
private val mNotesCollectionReference = mFirebaseFirestore.collection(COLLECTION_NOTES)
private val noteList = mutableListOf<NoteResponse>()
private var getNoteListSuccessListener: ((List<NoteResponse>) -> Unit)? = null
private var deleteNoteSuccessListener: ((List<NoteResponse>) -> Unit)? = null
override fun getNoteListSuccessListener(success: (List<NoteResponse>) -> Unit) {
getNoteListSuccessListener = success
}
override fun deleteNoteSuccessListener(success: (List<NoteResponse>) -> Unit) {
deleteNoteSuccessListener = success
}
override fun getNoteList() {
mNotesCollectionReference
.addSnapshotListener { value, _ ->
noteList.clear()
if (value != null) {
for (item in value) {
noteList
.add(item.toNoteResponse())
}
getNoteListSuccessListener?.invoke(noteList)
}
Log.e("NOTE_REPO", "$noteList")
}
}
override fun deleteNoteById(noteId: String) {
mNotesCollectionReference.document(noteId)
.delete()
.addOnSuccessListener {
deleteNoteSuccessListener?.invoke(noteList)
}
}
}
ViewModel layer is:
interface INoteViewModel {
val noteListStateFlow: StateFlow<List<NoteResponse>>
val noteDeletedStateFlow: StateFlow<List<NoteResponse>>
fun getNoteList()
fun deleteNoteById(noteId: String)
}
NoteViewModelImpl is:
class NoteViewModelImpl: ViewModel(), INoteViewModel {
private val mNoteRepository: INoteRepository = NoteRepositoryImpl()
private val _noteListStateFlow = MutableStateFlow<List<NoteResponse>>(mutableListOf())
override val noteListStateFlow: StateFlow<List<NoteResponse>>
get() = _noteListStateFlow.asStateFlow()
private val _noteDeletedStateFlow = MutableStateFlow<List<NoteResponse>>(mutableListOf())
override val noteDeletedStateFlow: StateFlow<List<NoteResponse>>
get() = _noteDeletedStateFlow.asStateFlow()
init {
// getNoteListSuccessListener
mNoteRepository
.getNoteListSuccessListener {
viewModelScope
.launch {
_noteListStateFlow.emit(it)
Log.e("NOTE_G_VM", "$it")
}
}
// deleteNoteSuccessListener
mNoteRepository
.deleteNoteSuccessListener {
viewModelScope
.launch {
_noteDeletedStateFlow.emit(it)
Log.e("NOTE_D_VM", "$it")
}
}
}
override fun getNoteList() {
// Get all notes
mNoteRepository.getNoteList()
}
override fun deleteNoteById(noteId: String) {
mNoteRepository.deleteNoteById(noteId = noteId)
}
}
and last but not least Fragment is:
class HomeFragment : Fragment() {
private lateinit var binding: FragmentHomeBinding
private val viewModel: INoteViewModel by viewModels<NoteViewModelImpl>()
private lateinit var adapter: NoteAdapter
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
binding = FragmentHomeBinding.inflate(inflater, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val recyclerView = binding.recyclerViewNotes
recyclerView.addOnScrollListener(
ExFABScrollListener(binding.fab)
)
adapter = NoteAdapter{itemView, noteId ->
if (noteId != null) {
showMenu(itemView, noteId)
}
}
recyclerView.adapter = adapter
// initView()
fetchFirestoreData()
binding.fab.setOnClickListener {
val action = HomeFragmentDirections.actionFirstFragmentToSecondFragment()
findNavController().navigate(action)
}
}
private fun fetchFirestoreData() {
// Get note list
viewModel
.getNoteList()
// Create list object
val noteList:MutableList<NoteResponse> = mutableListOf()
// Impose StateFlow
viewModel
.noteListStateFlow
.onEach { data ->
data.forEach {noteResponse ->
noteList.add(noteResponse)
adapter.submitList(noteList)
Log.e("NOTE_H_FRAG", "$noteResponse")
}
}.launchIn(viewLifecycleOwner.lifecycleScope)
}
//In the showMenu function from the previous example:
#SuppressLint("RestrictedApi")
private fun showMenu(v: View, noteId: String) {
val menuBuilder = MenuBuilder(requireContext())
SupportMenuInflater(requireContext()).inflate(R.menu.menu_note_options, menuBuilder)
menuBuilder.setCallback(object : MenuBuilder.Callback {
override fun onMenuItemSelected(menu: MenuBuilder, item: MenuItem): Boolean {
return when(item.itemId){
R.id.option_edit -> {
val action = HomeFragmentDirections.actionFirstFragmentToSecondFragment(noteId = noteId)
findNavController().navigate(action)
true
}
R.id.option_delete -> {
viewModel
.deleteNoteById(noteId = noteId)
// Create list object
val noteList:MutableList<NoteResponse> = mutableListOf()
viewModel
.noteDeletedStateFlow
.onEach {data ->
data.forEach {noteResponse ->
noteList.add(noteResponse)
adapter.submitList(noteList)
Log.e("NOTE_H_FRAG", "$noteResponse")
}
}.launchIn(viewLifecycleOwner.lifecycleScope)
true
} else -> false
}
}
override fun onMenuModeChange(menu: MenuBuilder) {}
})
val menuHelper = MenuPopupHelper(requireContext(), menuBuilder, v)
menuHelper.setForceShowIcon(true) // show icons!!!!!!!!
menuHelper.show()
}
}
With all the above logic I'm facing TWO issues
issue - 1
As mentioned here, I have added SnapshotListener on collection as:
override fun getNoteList() {
mNotesCollectionReference
.addSnapshotListener { value, _ ->
noteList.clear()
if (value != null) {
for (item in value) {
noteList
.add(item.toNoteResponse())
}
getNoteListSuccessListener?.invoke(noteList)
}
Log.e("NOTE_REPO", "$noteList")
}
}
with it if I change values of a document from Firebase Console, I get updated values in Repository and ViewModel, but list of notes is not being updated which is passed to adapter, so all the items are same.
issue - 2
If I delete any item from list/recyclerview using:
R.id.option_delete -> {
viewModel
.deleteNoteById(noteId = noteId)
// Create list object
val noteList:MutableList<NoteResponse> = mutableListOf()
viewModel
.noteDeletedStateFlow
.onEach {data ->
data.forEach {noteResponse ->
noteList.add(noteResponse)
adapter.submitList(noteList)
Log.e("NOTE_H_FRAG", "$noteResponse")
}
}.launchIn(viewLifecycleOwner.lifecycleScope)
still I get updated list(i.e new list of notes excluding deleted note) in Repository and ViewModel, but list of notes is not being updated which is passed to adapter, so all the items are same, no and exclusion of deleted item.
Question Where exactly I'm making mistake to initialize/update adapter? because ViewModel and Repository are working fine.
Make following changes:
In init{} block of NoteViewModelImpl :
// getNoteListSuccessListener
mNoteRepository
.getNoteListSuccessListener{noteResponseList ->
viewModelScope.launch{
_noteListStateFlow.emit(it.toList())
}
}
you must add .toList() if you want to emit list in StateFlow to get notified about updates, and in HomeFragment
private fun fetchFirestoreData() {
// Get note list
viewModel
.getNoteList()
// Impose StateFlow
lifecycleScope.launch {
viewModel.noteListStateFlow.collect { list ->
adapter.submitList(list.toMutableList())
}
}
}
That's it, I hope it works fine.
Try to remove additional lists of items in the fetchFirestoreData() and showMenu() (for item R.id.option_delete) methods of the HomeFragment fragment and see if it works:
// remove `val noteList:MutableList<NoteResponse>` in `fetchFirestoreData()` method
private fun fetchFirestoreData() {
...
// remove this line
val noteList:MutableList<NoteResponse> = mutableListOf()
// Impose StateFlow
viewModel
.noteListStateFlow
.onEach { data ->
adapter.submitList(data)
}.launchIn(viewLifecycleOwner.lifecycleScope)
}
And the same for the delete menu item (R.id.option_delete).

Android Recycleview DiffUtil doesn't work properly

I am using recycle view with diffutil in my application. but while I rotating or comeback from another screen the adapter gets updated. why is this happening?.
Here My ViewModel
class FeedsViewModel() : ViewModel() {
private val feedsRepository = FeedsRepository()
val feedsLiveData: MutableLiveData<Resource<UserFeeds>> = MutableLiveData()
init {
val apiParams = HashMap<String, String>()
apiParams["user_id"] = "1"
getFeeds(apiParams,"123"
}
fun getFeeds(apiParams: HashMap<String, String>, token: String) = viewModelScope.launch {
feedsLiveData.postValue(Resource.Loading())
val response = feedsRepository.getFeeds(apiParams, token)
if (response.isSuccessful) {
response.body()?.let { resultResponse ->
feedsLiveData.postValue(Resource.Success(resultResponse))
}
} else {
feedsLiveData.postValue(Resource.Error(response.message()))
}
}
}
I am using fragment to display it
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.recyclerViewFeeds.adapter = feedsAdapter
viewModel.feedsLiveData.observe(viewLifecycleOwner, Observer { response ->
when (response) {
is Resource.Success -> {
binding.progressBar.visibility = View.GONE
response.data?.let { userFeeds ->
feedsAdapter.differ.submitList(userFeeds.userPosts.toList())
binding.nooFeeds.visibility = View.GONE
}
is Resource.Error -> {....}
is Resource.Loading -> {....}
}
})
}
and my adapter
class FeedsAdapter(private val context: Context, private val itemClickListener: FeedsItemCallBack) :
RecyclerView.Adapter<FeedsAdapter.MyViewHolder>() {
class MyViewHolder(val bindin: ItemViewFeedsBinding) : RecyclerView.ViewHolder(bindin.root) {
}
private val differCallback = object : DiffUtil.ItemCallback<UserPost>() {
override fun areItemsTheSame(oldItem: UserPost, newItem: UserPost): Boolean {
return oldItem.postId == newItem.postId
}
override fun areContentsTheSame(oldItem: UserPost, newItem: UserPost): Boolean {
return oldItem == newItem
}
}
val differ = AsyncListDiffer(this, differCallback)
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
var feedsItem = differ.currentList[position]
holder.bindin.feedData = feedsItem;
holder.bindin.executePendingBindings()
}
override fun getItemCount(): Int {
return differ.currentList.size
}
}
Is this implementation is correct?.
Is this issue of ViewModel or adapter?
please help. Thanks in advance
you could distinguish the cases of your activity being created for
the first time and being restored from savedInstanceState. This is
done by overriding onSaveInstanceState and checking the parameter of
onCreate.
You could lock the activity in one orientation by adding
android:screenOrientation="portrait" (or "landscape") to
in your manifest.
You could tell the system that you meant to handle screen changes
for yourself by specifying
android:configChanges="orientation|screenSize" in the
tag. This way the activity will not be recreated, but will receive a
callback instead (which you can ignore as it's not useful for you).
Personally, I'd go with (3). Of course if locking the app to one of the orientations is fine with you, you can also go with (2).

Android Room with LiveData + ViewModel Refresh Question

I have a small app I am using to try learn more about some of the newer Android components. I'm finding it difficult to find information and understand how best to do what I want.
Currently: Open app -> load data + stores in DB -> display data in list
I want to be able to query data again upon button press.
I have 2 buttons, 1 to fetch data again, 1 to delete the list data from the DB.
Problem is that it seems you cannot refresh if you are observing on an instance of LiveData, which I am. I understand that however the way I found to actually do a Network call and store in the Database returns an instance of LiveData and I am not sure how best to proceed.
Let me show you the code.
Fragment
private val viewModel: quoteViewModel by viewModels()
private lateinit var binding: FragmentHomeBinding
private lateinit var adapter: QuoteAdapter
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding = FragmentHomeBinding.inflate(inflater, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
initRecyclerView()
setupRetrieveQuotesObserver()
setupDeleteDataListener()
setupFetchNewDataListener()
setupSwipeToRefresh()
}
private fun initRecyclerView() {
adapter = QuoteAdapter()
binding.recyclerView.layoutManager = LinearLayoutManager(requireContext())
binding.recyclerView.adapter = adapter
}
private fun setupDeleteDataListener() {
binding.removeQuotesButton.setOnClickListener {
viewModel.removeAllQuotes()
}
}
private fun setupFetchNewDataListener() {
binding.getQuotesButton.setOnClickListener {
viewModel.removeQuotes()
viewModel.getQuotes()
}
}
private fun setupRetrieveQuotesObserver() {
viewModel.quoteLiveDataList.observe(viewLifecycleOwner, Observer { result ->
when (result.status) {
NewResult.Status.SUCCESS -> {
result.data.let { adapter.setItems(ArrayList(result.data)) }
binding.progressBar.visibility = View.GONE
binding.swipeContainer.isRefreshing = false
}
NewResult.Status.ERROR -> {
binding.progressBar.visibility = View.GONE
Snackbar.make(binding.root, "Some error has occurred", Snackbar.LENGTH_SHORT)
.show()
}
NewResult.Status.LOADING -> {
binding.progressBar.visibility = View.VISIBLE
}
}
})
}
private fun setupSwipeToRefresh() {
binding.swipeContainer.setOnRefreshListener {
viewModel.getQuotes()
}
}
ViewModel
val quoteLiveDataList: LiveData<NewResult<List<Quote>>> = repository.quotes
fun getQuotes() = viewModelScope.launch {
repository.quotes
}
fun removeAllQuotes() = viewModelScope.launch {
repository.deleteAllQuotes()
}
Repository
val quotes = performGetOperation(
databaseQuery = { dao.getAllQuotes() },
networkCall = { remoteSource.getAllQuotes() },
saveCallResult = {
val quotesList = ArrayList<Quote>()
for (messageString in it.messages.non_personalized) {
quotesList.add(
Quote(
messageString,
FaceImageProvider().getRandomFacePicture(),
false
)
)
}
dao.insertQuotes(quotesList)
}
)
#WorkerThread
suspend fun deleteAllQuotes() = withContext(Dispatchers.IO) { dao.deleteAllQuotes() }
performGetOperation
This is a class I saw online for handling what I want to do. I think the issue stems from here as it is returning LiveData, I'm not sure how best to fix it
fun <T, A> performGetOperation(
databaseQuery: () -> LiveData<T>,
networkCall: suspend () -> NewResult<A>,
saveCallResult: suspend (A) -> Unit
): LiveData<NewResult<T>> =
liveData(Dispatchers.IO) {
emit(NewResult.loading())
val source = databaseQuery.invoke().map { NewResult.success(it) }
emitSource(source)
val responseStatus = networkCall.invoke()
if (responseStatus.status == NewResult.Status.SUCCESS) {
saveCallResult(responseStatus.data!!)
} else if (responseStatus.status == NewResult.Status.ERROR) {
emit(NewResult.error(responseStatus.message!!))
emitSource(source)
}
}
RemoteDataSource
suspend fun getQuotes() = getResult { service.getQuotes() }
getResult
protected suspend fun <T> getResult(call: suspend () -> Response<T>): NewResult<T> {
try {
val response = call.invoke()
if (response.isSuccessful) {
val body = response.body()
if (body != null) {
return NewResult.success(body)
}
}
return error("${response.code()} ${response.message()}")
} catch (e: Exception) {
return error(e.message ?: e.toString())
}
}
private fun <T> error(message: String): NewResult<T> {
Log.d("BaseDataSource", message)
return NewResult.error("Network called failed due to: $message")
}
NewResult
data class NewResult<out T>(val status: Status, val data: T?, val message: String?) {
enum class Status {
SUCCESS,
ERROR,
LOADING,
}
companion object {
fun <T> success(data: T): NewResult<T> {
return NewResult(Status.SUCCESS, data, null)
}
fun <T> error(message: String, data: T? = null): NewResult<T> {
return NewResult(Status.ERROR, data, message)
}
fun <T> loading(data: T? = null): NewResult<T> {
return NewResult(Status.LOADING, data, null)
}
}
Apologies for the very long message, but I guess I need to show all the little bits and bobs I'm using.
I think the problem is in the Fragment where I do viewModel.quoteLiveDataList.observe, as it is returning a new LiveData if it is called again. So I'm not sure how I can do another server call and update the DB and return it here.
Appreciate any help!
Thanks
Use Transformations.switchMap on a MutableLiveData to trigger your repository call like it is done here in the GithubBrowserSample project. This will allow you to implement the refresh functionality -
private val _getQuotes = MutableLiveData<Boolean>()
val quotes: LiveData<NewResult<List<Quote>>> = _getQuotes.switchMap { getQuotes ->
repository.quotes
}
fun getQuotes() {
_getQuotes.value = true
}
fun refresh() {
_getQuotes.value?.let {
_getQuotes.value = it
}
}

CoroutineScope by MainScope() launch not executing

I am trying to use the MainScope() scope. I thought this allowed me to just call launch whenever I need a new coroutine with the option of specifying which Dispatcher I want it to run on if I don't want it on Dispatchers.Main. However some of my calls to launch don't execute at all.
This code first retrieves a setting db value from Room.
When the preference switch is clicked, it performs a network request to write a new setting on the server.
If the response is successful, I want to update the local db value in Room. The second launch within the observed response is never executed. Without a call to launch, I am (correctly) told by Room not to write on the main thread.
class PrefsFragment : PreferenceFragmentCompat(), Injectable, CoroutineScope by MainScope() {
#Inject
lateinit var settings: BranchSettingsRepository
#Inject
lateinit var preferencesHelper: PreferencesHelper
var groupID = 0
var branchID = 0
override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
setPreferencesFromResource(R.xml.preferences, rootKey)
}
override fun onViewCreated(view: View, #Nullable savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
groupID = preferencesHelper.merchantGroupID.toInt()
branchID = preferencesHelper.merchantBranchID.toInt()
createAutoAcceptSetting(view)
}
private fun createAutoAcceptSetting(root: View) {
launch(Dispatchers.IO) {
val setting = settings.getSettingByName(preferencesHelper.merchantBranchID, AUTO_ACCEPT)
if (setting != null) {
val preference = findPreference<SwitchPreferenceCompat>(AUTO_ACCEPT)
preference?.onPreferenceChangeListener = Preference.OnPreferenceChangeListener { pref, newValue ->
var valueAsIntString = "0"
if (newValue as Boolean) {
valueAsIntString = "1"
}
updateSetting(groupID, branchID, setting.id, valueAsIntString)
.observe(viewLifecycleOwner, Observer { response ->
response?.let {
if (it.status == Status.SUCCESS) {
Timber.i("New setting updated (old value was: $setting)")
Timber.i("launching db write with value: $valueAsIntString")
launch(Dispatchers.IO) {
//This code is never executed
setting.value = valueAsIntString
Timber.i("writing new setting: $setting")
settings.insertSetting(setting)
}
}
}
})
true
}
}
}
}
override fun onDestroy() {
super.onDestroy()
cancel()
}
}

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