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Two dependent request and recyclerView adapter

I have two requests that depend on each other and I want to pass both results to the recyclerView adapter.
Unfortunately, following code does not return data_1 in collect. But when I commented out second collect with data_2 then I see result for data_1.
class MyViewModel(UUID: GUID): ViewModel() {
private val _data_1: MutableStateFlow<List<Example>> = MutableStateFlow(emptyList())
val data_1: StateFlow<List<Example>> get() = _data_1.asStateFlow()
private val _data_2: MutableStateFlow<List<Example_2>> = MutableStateFlow(emptyList())
val data_2: StateFlow<List<Example_2>> get() = _data_2.asStateFlow()
init {
viewModelScope.launch(Dispatchers.IO) {
_repository.getData(UUID).collect { data_1 ->
_data_1.value = data_1
getSecondData(data_1)
}
}
private suspend fun getSecondData(item: List<Example>) {
val list = mutableListOf<Event>()
coroutineScope {
for (item in items) {
async(Dispatchers.IO) {
_repository.getSecondData(item).collect { it ->
list.add(it)
}
}.await()
}
_data_2.value = list
}
}
}
Fragment() {
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
viewLifecycleOwner.lifecycleScope.launch(Dispatchers.IO) {
viewLifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) {
myViewModel.data_1.collect { data_1 ->
myViewModel.data_2.collect { data_2 ->
withContext(Dispatchers.Main) {
binding.myRecyclerView.adapter = MyListAdapter(data_1, data_2)
}
}
}
}
}
}
I have check with Log.d that data_1 with data_2 returns records. I have tried storing data_1 in private variable in fragment before calling second collect. I have tried joinAll option but together with launch/collect it will never work.
Why is it not working and what should I do to fix it?

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).

StateFlow: Cancellation of Older Emitted State After Collecting

I m relatively new in kotlin flows and I m creating the Login Module using Flows in android. I have been stuck from past few days in flows as I m collecting it in ViewModels but I m facing problem when requesting with wrong Credentials its caching all the state. After entering the right credentials the user navigate to main Activity but the instance of the MainActivity is being created with every emitted State: Example(User Enter 3 wrong Credential and 1 Right Credential: 4 Instance of MainActivity Created). So, Is there any way that I can cancel the previous emit and only show the latest request. I m using the collectLatest as well but its not working too. Below is the code.
LoginActivity
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(mViewBinding.root)
loginListener()
}
override fun onStart() {
super.onStart()
initViews()
handleNetworkChanges()
}
private fun observeLogin() {
lifecycleScope.launchWhenCreated {
mViewModel.loginCredentials.collect { state ->
when(state){
is State.Loading -> {
showLoading()
}
is State.Success -> {
Timber.d("I m in Success" + state.data)
val intent = Intent(this#LoginActivity,MainActivity::class.java)
startActivity(intent)
closeLoading()
finish()
}
is State.Error -> {
val errorResponse = gson.fromJson(state.message,LoginResponse::class.java)
showToast(errorResponse.messages)
closeLoading()
}
}
}
}
}
private fun loginListener() {
mViewBinding.neumorphButtonSignIn.setOnClickListener {
observeLogin()
phoneNumber = mViewBinding.edtPhoneNumber.text.toString()
pin = mViewBinding.oldPIN.text.toString()
if (phoneNumber.isValidPhone()) {
sendLoginCredentials(phoneNumber ,pin)
}
else {
mViewBinding.edtPhoneNumber.snack("Please Enter valid phone number") {
action("ok") {
dismiss()
}
}
}
}
}
private fun sendLoginCredentials(phoneNumber: String , pin: String) = mViewModel.postLoginCredentials("03XXXX" , "1234")
LoginViewModel
#ExperimentalCoroutinesApi
#HiltViewModel
class LoginViewModel #Inject constructor(
private val loginRepository: LoginRepository,
) : ViewModel() {
private val _loginCredentials: MutableStateFlow<State<LoginResponse>> = MutableStateFlow(State.Empty())
val loginCredentials: StateFlow<State<LoginResponse>> get() = _loginCredentials
fun postLoginCredentials(phoneNumber: String, pin: String) {
Timber.d("postLoginCredentials: $phoneNumber + $pin")
_loginCredentials.value = State.loading()
viewModelScope.launch {
loginRepository.login(LoginRequest(phoneNumber,pin))
.map { response -> State.fromResource(response) }
.collect{state -> _loginCredentials.value = state }
}
}
}
LoginRepository
class LoginRepository #Inject constructor(
private val apiInterface: APIInterface
) {
fun login(loginRequest: LoginRequest): Flow<ResponseAPI<LoginResponse>> {
return object : NetworkBoundRepository<LoginRequest, LoginResponse>() {
override suspend fun fetchFromRemote(): Response<LoginResponse> = apiInterface.createLoginRequest(
loginRequest
)
}.asFlow()
}
NetworkBoundRepository
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 {
// Something went wrong! Emit Error state.
emit(ResponseAPI.Failed(apiResponse.errorBody()!!.string()))
}
}.catch { e ->
e.printStackTrace()
emit(ResponseAPI.Failed("Network error! Can't get latest posts."))
}
#MainThread
protected abstract suspend fun fetchFromRemote(): Response<REQUEST>
}
Is there any way that I can create One Instance of MainAcitivity while ignoring the older emitted Responses? Any Operator which can work. Any help in this regard is highly appreciated. Thanks.

Actually, I was calling the observeLogin() from the login click Listener which was creating this mess in my project when I move this to onCreate(). Everything works the way as intended. So, posting this for newbie that won't stuck into this.

Android: Firebase Object is null when using kotlin flow

My problem is, that when I try to get a document out of my database, that this document aka the object is always null. I only have this problem when I use Kotlin Coroutines to get the document out of my database. Using the standard approach with listeners do work.
EmailRepository
interface EmailRepository {
suspend fun getCalibratePrice(): Flow<EmailEntity?>
suspend fun getRepairPrice(): Flow<EmailEntity?>
}
EmailRepository Implementation
class EmailRepositoryImpl #Inject constructor(private val db: FirebaseFirestore) : EmailRepository {
fun hasInternet(): Boolean {
return true
}
// This works! When using flow to write a document, the document is written!
override fun sendEmail(email: Email)= flow {
emit(EmailStatus.loading())
if (hasInternet()) {
db.collection("emails").add(email).await()
emit(EmailStatus.success(Unit))
} else {
emit(EmailStatus.failed<Unit>("No Email connection"))
}
}.catch {
emit(EmailStatus.failed(it.message.toString()))
}.flowOn(Dispatchers.Main)
// This does not work! "EmailEntity" is always null. I checked the document path!
override suspend fun getCalibratePrice(): Flow<EmailEntity?> = flow {
val result = db.collection("emailprice").document("Kalibrieren").get().await()
emit(result.toObject<EmailEntity>())
}.catch {
}.flowOn(Dispatchers.Main)
// This does not work! "EmailEntity" is always null. I checked the document path!
override suspend fun getRepairPrice(): Flow<EmailEntity?> = flow {
val result = db.collection("emailprice").document("Reparieren").get().await()
emit(result.toObject<EmailEntity>())
}.catch {
}.flowOn(Dispatchers.Main)
}
Viewmodel where I get the data
init {
viewModelScope.launch {
withContext(Dispatchers.IO) {
if (subject.value != null){
when(subject.value) {
"Test" -> {
emailRepository.getCalibratePrice().collect {
emailEntity.value = it
}
}
"Toast" -> {
emailRepository.getRepairPrice().collect {
emailEntity.value = it
}
}
}
}
}
}
}
private val emailEntity = MutableLiveData<EmailEntity?>()
private val _subject = MutableLiveData<String>()
val subject: LiveData<String> get() = _subject
Fragment
#AndroidEntryPoint
class CalibrateRepairMessageFragment() : EmailFragment<FragmentCalibrateRepairMessageBinding>(
R.layout.fragment_calibrate_repair_message,
) {
// Get current toolbar Title and send it to the next fragment.
private val toolbarText: CharSequence by lazy { toolbar_title.text }
override val viewModel: EmailViewModel by navGraphViewModels(R.id.nav_send_email) { defaultViewModelProviderFactory }
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
// Here I set the data from the MutableLiveData "subject". I don't know how to do it better
viewModel.setSubject(toolbarText.toString())
}
}
One would say, that the Firebase rules are the problems here, but that should not be the case here, because the database is open and using the listener approach does work.
I get the subject.value from my CalibrateRepairMessageFragment. When I don't check if(subject.value != null) I get a NullPointerException from my init block.
I will use the emailEntitiy only in my viewModel and not outside it.
I appreciate every help, thank you.
EDIT
This is the new way I get the data. The object is still null! I've also added Timber.d messages in my suspend functions which also never get executed therefore flow never throws an error.. With this new approach I don't get a NullPointerException anymore
private val emailEntity = liveData {
when(subject.value) {
"Test" -> emailRepository.getCalibratePrice().collect {
emit(it)
}
"Toast" -> emailRepository.getRepairPrice().collect {
emit(it)
}
// Else block is never executed, therefore "subject.value" is either Test or toast and the logic works. Still error when using flow!
else -> EmailEntity("ERROR", 0F)
}
}
I check if the emailEntity is null or not with Timber.d("EmailEntity is ${emailEntity.value}") in one of my functions.
I then set the price with val price = MutableLiveData(emailEntity.value?.basePrice ?: 1000F) but because emailentity is null the price is always 1000
EDIT 2
I have now further researched the problem and made a big step forward. When observing the emailEntity from a fragment like CalibrateRepairMessageFragment the value is no longer null.
Furthermore, when observing emailEntity the value is also not null in viewModel, but only when it is observed in one fragment! So how can I observe emailEntity from my viewModel or get the value from my repository and use it in my viewmodel?

Okay, I have solved my problem, this is the final solution:
Status class
sealed class Status<out T> {
data class Success<out T>(val data: T) : Status<T>()
class Loading<T> : Status<T>()
data class Failure<out T>(val message: String?) : Status<T>()
companion object {
fun <T> success(data: T) = Success<T>(data)
fun <T> loading() = Loading<T>()
fun <T> failed(message: String?) = Failure<T>(message)
}
}
EmailRepository
interface EmailRepository {
fun sendEmail(email: Email): Flow<Status<Unit>>
suspend fun getCalibratePrice(): Flow<Status<CalibrateRepairPricing?>>
suspend fun getRepairPrice(): Flow<Status<CalibrateRepairPricing?>>
}
EmailRepositoryImpl
class EmailRepositoryImpl (private val db: FirebaseFirestore) : EmailRepository {
fun hasInternet(): Boolean {
return true
}
override fun sendEmail(email: Email)= flow {
Timber.d("Executed Send Email Repository")
emit(Status.loading())
if (hasInternet()) {
db.collection("emails").add(email).await()
emit(Status.success(Unit))
} else {
emit(Status.failed<Unit>("No Internet connection"))
}
}.catch {
emit(Status.failed(it.message.toString()))
}.flowOn(Dispatchers.Main)
// Sends status and object to viewModel
override suspend fun getCalibratePrice(): Flow<Status<CalibrateRepairPricing?>> = flow {
emit(Status.loading())
val entity = db.collection("emailprice").document("Kalibrieren").get().await().toObject<CalibrateRepairPricing>()
emit(Status.success(entity))
}.catch {
Timber.d("Error on getCalibrate Price")
emit(Status.failed(it.message.toString()))
}
// Sends status and object to viewModel
override suspend fun getRepairPrice(): Flow<Status<CalibrateRepairPricing?>> = flow {
emit(Status.loading())
val entity = db.collection("emailprice").document("Kalibrieren").get().await().toObject<CalibrateRepairPricing>()
emit(Status.success(entity))
}.catch {
Timber.d("Error on getRepairPrice")
emit(Status.failed(it.message.toString()))
}
}
ViewModel
private lateinit var calibrateRepairPrice: CalibrateRepairPricing
private val _calirateRepairPriceErrorState = MutableLiveData<Status<Unit>>()
val calibrateRepairPriceErrorState: LiveData<Status<Unit>> get() = _calirateRepairPriceErrorState
init {
viewModelScope.launch {
when(_subject.value.toString()) {
"Toast" -> emailRepository.getCalibratePrice().collect {
when(it) {
is Status.Success -> {
calibrateRepairPrice = it.data!!
_calirateRepairPriceErrorState.postValue(Status.success(Unit))
}
is Status.Loading -> _calirateRepairPriceErrorState.postValue(Status.loading())
is Status.Failure -> _calirateRepairPriceErrorState.postValue(Status.failed(it.message))
}
}
else -> emailRepository.getRepairPrice().collect {
when(it) {
is Status.Success -> {
calibrateRepairPrice = it.data!!
_calirateRepairPriceErrorState.postValue(Status.success(Unit))
}
is Status.Loading -> _calirateRepairPriceErrorState.postValue(Status.loading())
is Status.Failure -> _calirateRepairPriceErrorState.postValue(Status.failed(it.message))
}
}
}
price.postValue(calibrateRepairPrice.head!!.basePrice)
}
}
You can now observe the status in one of your fragments (but you dont need to!)
Fragment
viewModel.calibrateRepairPriceErrorState.observe(viewLifecycleOwner) { status ->
when(status) {
is Status.Success -> requireContext().toast("Price successfully loaded")
is Status.Loading -> requireContext().toast("Price is loading")
is Status.Failure -> requireContext().toast("Error, Price could not be loaded")
}
}
This is my toast extensions function:
fun Context.toast(text: String, duration: Int = Toast.LENGTH_SHORT) {
Toast.makeText(this, text, duration).show()
}

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
}
}