I want to show ProgressDialog while fetching data from ViewModel and it works fine when I fetch data for the first time, but when I want to refresh the data from API the ProgressDialog starts and does not stops
I create MutableLiveData<Boolean>() and try to manage the visibility but it's not working
This is how i refresh my data from my Activity
private fun loadNorthTram() {
val model =
ViewModelProviders.of(this#MainActivity).get(MyViewModelNorth::class.java)
model.isNorthUpdating.observe(
this#MainActivity,
Observer { b ->
if (b!!)
AppUtil.showProgressSpinner(this#MainActivity)
else
AppUtil.dismissProgressDialog()
})
model.getNorthTrams().observe(this#MainActivity, Observer
{
if (it != null) {
setData(it)
}
})
}
Below is my ViewModel class
class MyViewModelNorth : ViewModel() {
private lateinit var mtoken: String
private val apiService: ApiInterface = ApiClient.client.create(ApiInterface::class.java)
private lateinit var trams: MutableLiveData<TramModel>
val isNorthUpdating = MutableLiveData<Boolean>().default(false)
fun getNorthTrams(): MutableLiveData<TramModel> {
isNorthUpdating.value = true
if (!::trams.isInitialized) {
trams = MutableLiveData()
callTokenAPI()
}
return trams
}
private fun callTokenAPI() {
val tokenObservable: Observable<TokenModel> = apiService.fetchToken()
tokenObservable
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doOnNext { self ->
mtoken = self.responseObject[0].DeviceToken
callTramAPI()
}
.subscribe(getTokenObserver())
}
private fun callTramAPI() {
val apiService: ApiInterface = ApiClient.client.create(ApiInterface::class.java)
val observable: Observable<TramModel> = apiService.fetchTrams(AppUtil.NORTH_TRAMS, mtoken)
observable
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(getTramObserver())
}
private fun getTokenObserver(): Observer<TokenModel> {
return object : Observer<TokenModel> {
override fun onComplete() {}
override fun onSubscribe(d: Disposable) {}
override fun onNext(tokenModel: TokenModel) {}
override fun onError(e: Throwable) {
if (e is HttpException) {
val errorBody = e.response().errorBody()
HttpErrorUtil(e.code()).handelError()
}
}
}
}
private fun getTramObserver(): Observer<TramModel> {
return object : Observer<TramModel> {
override fun onComplete() {
isNorthUpdating.value = false
}
override fun onSubscribe(d: Disposable) {}
override fun onNext(t: TramModel) {
if (!t.hasError && t.hasResponse)
trams.value = t
else if (t.errorMessage.isBlank())
applicationContext().showToast(t.errorMessage)
else
applicationContext().showToast(applicationContext().getString(R.string.something_wrong))
}
override fun onError(e: Throwable) {
if (e is HttpException) {
val errorBody = e.response().errorBody()
HttpErrorUtil(e.code()).handelError()
}
}
}
}
public fun getIsNothUpdating(): LiveData<Boolean> {
return isNorthUpdating
}
fun <T : Any?> MutableLiveData<T>.default(initialValue: T) = apply { setValue(initialValue) }
}
I have not tested your code but I think your problem is in function getNorthTrams() in viewmodel.
First time when you fetch data, trams is not initialized, your api call is happening and at only onCompleted, you are setting isNorthUpdating.value = false. This code works.
But when you refresh data, trams is already initialized. So, there is no case for isNorthUpdating.value = false, which is causing progress dialog to not dismiss.
So I think you should handle else case in your viewmodel.
fun getNorthTrams(): MutableLiveData<TramModel> {
isNorthUpdating.value = true
if (!::trams.isInitialized) {
trams = MutableLiveData()
callTokenAPI()
}else{
//do your thing for refresh
isNorthUpdating.value = false
}
return trams
}
Also, in api call, if error occur, you should set isNorthUpdating to false and show some error message. Otherwise, progress dialog will always be showing even if some error occur in api call.
Related
I want to call 2 retrofit services in parallel and then do an action only when both of them finished, but I don't seem to figuer it out how.
I have a viewModel where I have defined my services:
var config= List<Configuration>
fun getClientProducts() {
getClientClientConfigUseCase
.build(this)
.executeWithError({ config ->
config = config
}, {
})
}
var therapies = List<DtoTherapy>
fun getTherapies() {
getTherapiesUseCase
.build(this)
.executeWithError({ config ->
therapies = it
}, {
})
}
And then I want to call both services in parallel in my fragment:
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
setupUi(view)
loadUserData()
viewModel.getClientProducts()
viewModel.getTherapies()
}
And when both variables config and therapies have the value do an action. But as I said maybe one service take 1 sec to respond and another 4 secs, and I want only to perfom an action when both have finished. Any help with be appreciated.
Here is the class I use to build the use case call:
abstract class SingleUseCase<T> : UseCase() {
private lateinit var single: Single<T>
private lateinit var useCaseInterface: UseCaseInterface
private var withLoader: Boolean = false
private var withErrorMessage: Boolean = false
internal abstract fun buildUseCaseSingle(): Single<T>
fun build(useCaseInterface: UseCaseInterface): SingleUseCase<T> {
this.withLoader = false
this.withErrorMessage = false
this.useCaseInterface = useCaseInterface
this.single = buildUseCaseSingle()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doAfterSuccess { useCaseInterface.onSuccess(it) }
return this
}
fun withLoader(): SingleUseCase<T> {
this.withLoader = true
return this
}
fun withErrorMessage(): SingleUseCase<T> {
this.withErrorMessage = true
return this
}
fun single(): Single<T> {
return this.single
}
fun execute(onSuccess: ((t: T) -> Unit)) {
useCaseInterface.onPrepareRequest(withLoader)
buildObservable(onSuccess)
}
private fun buildObservable(onSuccess: ((t: T) -> Unit)) {
disposeLast()
lastDisposable = single
.doFinally { useCaseInterface.onFinishRequest(this.withLoader) }
.subscribe(
{ onSuccess(it) },
{
useCaseInterface.onError(mapError(it), withErrorMessage)
})
lastDisposable?.let {
compositeDisposable.add(it)
}
}
fun executeWithError(onSuccess: ((success: T) -> Unit), onError: ((error: ApiError ) -> Unit)) {
useCaseInterface.onPrepareRequest(withLoader)
buildObservable(onSuccess, onError)
}
private fun buildObservable(onSuccess: ((success: T) -> Unit), onError: ((error: ApiError ) -> Unit)) {
disposeLast()
lastDisposable = single
.doFinally { useCaseInterface.onFinishRequest(this.withLoader) }
.subscribe(
{ onSuccess(it) },
{
onError(mapError(it))
useCaseInterface.onError(mapError(it), withErrorMessage)
})
lastDisposable?.let {
compositeDisposable.add(it)
}
}
private fun mapError(t: Throwable): ApiError {
return if(t is HttpException) {
val apiError = t.response()?.errorBody()?.string()
try {
ApiError (t.code(), t.response()?.errorBody()?.string(), Gson().fromJson(apiError, GenericError::class.java))
} catch(e: Exception) {
ApiError (-2, "Unkown error")
}
} else ApiError (-1, "Unkown error")
}
}
And this is a specific usecase class:
class GetClientConfigUseCase #Inject constructor(private val repository: UserRepository) :
SingleUseCase<ClientConfigResponse>() {
override fun buildUseCaseSingle(): Single<ClientConfigResponse> {
return repository.getUserConfig()
}
}
I guess you need zip operation. With zip operation you can have a result of two observable in one place when both of them received data.
Observable<List<ClientProducts>> observable1 = ...
Observable<List<DtoTherapy>> observable2 = ...
Observable.zip(observable1, observable2, new BiFunction<List<ClientProducts>, List<DtoTherapy>, Result>() {
#Override
public Result apply(List<ClientProducts> products, List<DtoTherapy> therapies) throws Exception
{
// here you have both of your data
// do operations on products and therapies
// then return the result
return result;
}
});
I was trying to get response from viewModel But, I am having hard time to use the response data on another activity to display it on a text view.
I have already setup the backend for the repo's and interfaces, data classes etc...
Thank you!!!
// View Model
class HomeActivityViewModel : ViewModel() {
lateinit var createPostLiveData: MutableLiveData<PostResponseData?>
init {
createPostLiveData = MutableLiveData()
}
fun getPostLiveObserver(): MutableLiveData<PostResponseData?> {
return createPostLiveData
}
fun createPostData(postdata: PostData) {
val retroService = RetrofitApiFactory.retroInstance().create(ChefApi::class.java)
val call = retroService.postData(postdata)
call.enqueue(object : Callback<PostResponseData> {
override fun onResponse(
call: Call<PostResponseData>,
response: Response<PostResponseData>
) {
if (response.isSuccessful) {
createPostLiveData.postValue(response.body())
var text = response.body()!!.choices[0].text
Log.d("response", text) // only shows the one in the viewModel
} else {
createPostLiveData.postValue(null)
Log.d("failed", response.errorBody().toString())
}
}
override fun onFailure(call: Call<PostResponseData>, t: Throwable) {
Log.d("failed", t.message.toString())
createPostLiveData.postValue(null)
}
})
}
}
Activity.kt
class HomeActivity : AppCompatActivity() {
lateinit var mAuth: FirebaseAuth
lateinit var viewModel: HomeActivityViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_home_actvity)
mAuth = FirebaseAuth.getInstance()
initViewModel()
generate.setOnClickListener {
createPost()
}
logout.setOnClickListener {
logoutUser()
}
}
private fun createPost() {
// creating a post
val prompt = "Some string..."
val postdata = PostData(120, prompt, 0.3, 1.0, 0.0)
viewModel.createPostData(postdata)
}
private fun initViewModel() {
// initialize view model
viewModel = ViewModelProvider(this).get(HomeActivityViewModel::class.java)
viewModel.getPostLiveObserver().observe(this, Observer<PostResponseData?> {
if (it == null) {
Toast.makeText(this#HomeActivity, "Failed to post data", Toast.LENGTH_SHORT).show()
} else {
Toast.makeText(this#HomeActivity, "Successfully posted data", Toast.LENGTH_SHORT)
.show()
}
})
}
private fun logoutUser() {
mAuth.signOut()
updateUI()
}
private fun updateUI() {
val intent = Intent(this#HomeActivity, MainActivity::class.java)
startActivity(intent)
finish()
}
Try to change your HomeActivityViewModel class and add a LiveData object to it:
class HomeActivityViewModel : ViewModel() {
var _createPostLiveData: MutableLiveData<PostResponseData?>()
// Live data instance
val createPostLiveData
get() = _createPostLiveData
fun createPostData(postdata: PostData) {
val retroService = RetrofitApiFactory.retroInstance().create(ChefApi::class.java)
val call = retroService.postData(postdata)
call.enqueue(object : Callback<PostResponseData> {
override fun onResponse(
call: Call<PostResponseData>,
response: Response<PostResponseData>
) {
if (response.isSuccessful) {
// Update live data value
_createPostLiveData.value = response.body()
var text = response.body()!!.choices[0].text
Log.d("response", text) // only shows the one in the viewModel
} else {
// Update live data value
_createPostLiveData.value = null
Log.d("failed", response.errorBody().toString())
}
}
override fun onFailure(call: Call<PostResponseData>, t: Throwable) {
Log.d("failed", t.message.toString())
// Update live data value
_createPostLiveData.value = null
}
})
}
}
You should then be able to observe the LiveData instance in your Activity:
class HomeActivity : AppCompatActivity() {
lateinit var mAuth: FirebaseAuth
// Initialize view model in declaration
private val viewModel: HomeActivityViewModel by viewModels()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_home_actvity)
mAuth = FirebaseAuth.getInstance()
// Observe for `createPostLiveData` changes
viewModel.createPostLiveData.observe(this) {
if (it == null) {
Toast.makeText(this#HomeActivity, "Failed to post data", Toast.LENGTH_SHORT).show()
} else {
Toast.makeText(this#HomeActivity, "Successfully posted data", Toast.LENGTH_SHORT)
.show()
}
}
generate.setOnClickListener {
createPost()
}
logout.setOnClickListener {
logoutUser()
}
}
private fun createPost() {
// creating a post
val prompt = "Some string..."
val postdata = PostData(120, prompt, 0.3, 1.0, 0.0)
viewModel.createPostData(postdata)
}
...
I've just finished my first Android App. It works as it should but, as you can imagine, there's a lot of spaghetti code and lack of performance. From what I've learned on Android and Kotlin language making this project (and a lot of articles/tutorials/SO answers) I'm trying to start it again from scratch to realize a better version. For now I'd like to keep it as simple as possible, just to better understand how to handle API calls with Retrofit and MVVM pattern, so no Volley/RXjava/Dagger etc.
I'm starting from the login obviously; I would like to make a post request to simply compare the credentials, wait for the response and, if positive, show a "loading screen" while fetching and processing data to show in the home page. I'm not storing any information so I have realized a singleton class that holds data as long as the app is running (btw, is there another way to do it?).
RetrofitService
private val retrofitService = Retrofit.Builder()
.addConverterFactory(
GsonConverterFactory
.create(
GsonBuilder()
.excludeFieldsWithoutExposeAnnotation()
.setLenient().setDateFormat("yyyy-MM-dd")
.create()
)
)
.addConverterFactory(RetrofitConverter.create())
.baseUrl(BASE_URL)
.build()
`object ApiObject {
val retrofitService: ApiInterface by lazy {
retrofitBuilder.create(ApiInterface::class.java) }
}
ApiInterface
interface ApiInterface {
#GET("workstation/{date}")
suspend fun getWorkstations(
#Path("date") date: Date
): List<Workstation>
#GET("reservation/{date}")
suspend fun getReservations(
#Path("date") date: Date
): List<Reservation>
#GET("user")
suspend fun getUsers(): List<User>
#GET("user/login")
suspend fun validateLoginCredentials(
#Query("username") username: String,
#Query("password") password: String
): Response<User>
ApiResponse
sealed class ApiResponse<T> {
companion object {
fun <T> create(response: Response<T>): ApiResponse<T> {
return if(response.isSuccessful) {
val body = response.body()
// Empty body
if (body == null || response.code() == 204) {
ApiSuccessEmptyResponse()
} else {
ApiSuccessResponse(body)
}
} else {
val msg = response.errorBody()?.string()
val errorMessage = if(msg.isNullOrEmpty()) {
response.message()
} else {
msg.let {
return#let JSONObject(it).getString("message")
}
}
ApiErrorResponse(errorMessage ?: "Unknown error")
}
}
}
}
class ApiSuccessResponse<T>(val data: T): ApiResponse<T>()
class ApiSuccessEmptyResponse<T>: ApiResponse<T>()
class ApiErrorResponse<T>(val errorMessage: String): ApiResponse<T>()
Repository
class Repository {
companion object {
private var instance: Repository? = null
fun getInstance(): Repository {
if (instance == null)
instance = Repository()
return instance!!
}
}
private var singletonClass = SingletonClass.getInstance()
suspend fun validateLoginCredentials(username: String, password: String) {
withContext(Dispatchers.IO) {
val result: Response<User>?
try {
result = ApiObject.retrofitService.validateLoginCredentials(username, password)
when (val response = ApiResponse.create(result)) {
is ApiSuccessResponse -> {
singletonClass.loggedUser = response.data
}
is ApiSuccessEmptyResponse -> throw Exception("Something went wrong")
is ApiErrorResponse -> throw Exception(response.errorMessage)
}
} catch (error: Exception) {
throw error
}
}
}
suspend fun getWorkstationsListFromService(date: Date) {
withContext(Dispatchers.IO) {
val workstationsListResult: List<Workstation>
try {
workstationsListResult = ApiObject.retrofitService.getWorkstations(date)
singletonClass.rWorkstationsList.postValue(workstationsListResult)
} catch (error: Exception) {
throw error
}
}
}
suspend fun getReservationsListFromService(date: Date) {
withContext(Dispatchers.IO) {
val reservationsListResult: List<Reservation>
try {
reservationsListResult = ApiObject.retrofitService.getReservations(date)
singletonClass.rReservationsList.postValue(reservationsListResult)
} catch (error: Exception) {
throw error
}
}
}
suspend fun getUsersListFromService() {
withContext(Dispatchers.IO) {
val usersListResult: List<User>
try {
usersListResult = ApiObject.retrofitService.getUsers()
singletonClass.rUsersList.postValue(usersListResult.let { usersList ->
usersList.filterNot { user -> user.username == "admin" }
.sortedWith(Comparator { x, y -> x.surname.compareTo(y.surname) })
})
} catch (error: Exception) {
throw error
}
}
}
SingletonClass
const val FAILED = 0
const val COMPLETED = 1
const val RUNNING = 2
class SingletonClass private constructor() {
companion object {
private var instance: SingletonClass? = null
fun getInstance(): SingletonClass {
if (instance == null)
instance = SingletonClass()
return instance!!
}
}
//User
var loggedUser: User? = null
//Workstations List
val rWorkstationsList = MutableLiveData<List<Workstation>>()
//Reservations List
val rReservationsList = MutableLiveData<List<Reservation>>()
//Users List
val rUsersList = MutableLiveData<List<User>>()
}
ViewModel
class ViewModel : ViewModel() {
private val singletonClass = SingletonClass.getInstance()
private val repository = Repository.getInstance()
//MutableLiveData
//Login
private val _loadingStatus = MutableLiveData<Boolean>()
val loadingStatus: LiveData<Boolean>
get() = _loadingStatus
private val _successfulAuthenticationStatus = MutableLiveData<Boolean>()
val successfulAuthenticationStatus: LiveData<Boolean>
get() = _successfulAuthenticationStatus
//Data fetch
private val _listsLoadingStatus = MutableLiveData<Int>()
val listsLoadingStatus: LiveData<Int>
get() = _listsLoadingStatus
private val _errorMessage = MutableLiveData<String>()
val errorMessage: LiveData<String>
get() = _errorMessage
fun onLoginClicked(username: String, password: String) {
launchLoginAuthentication {
repository.validateLoginCredentials(username, password)
}
}
private fun launchLoginAuthentication(block: suspend () -> Unit): Job {
return viewModelScope.launch {
try {
_loadingStatus.value = true
block()
} catch (error: Exception) {
_errorMessage.postValue(error.message)
} finally {
_loadingStatus.value = false
if (singletonClass.loggedUser != null)
_successfulAuthenticationStatus.value = true
}
}
}
fun onLoginPerformed() {
val date = Calendar.getInstance().time
launchListsFetch {
//how to start these all at the same time? Then wait until their competion
//and call the two methods below?
repository.getReservationsListFromService(date)
repository.getWorkstationsListFromService(date)
repository.getUsersListFromService()
}
}
private fun launchListsFetch(block: suspend () -> Unit): Job {
return viewModelScope.async {
try {
_listsLoadingStatus.value = RUNNING
block()
} catch (error: Exception) {
_listsLoadingStatus.value = FAILED
_errorMessage.postValue(error.message)
} finally {
//I'd like to perform these operations at the same time
prepareWorkstationsList()
prepareReservationsList()
//and, when both completed, set this value
_listsLoadingStatus.value = COMPLETED
}
}
}
fun onToastShown() {
_errorMessage.value = null
}
}
LoginActivity
class LoginActivity : AppCompatActivity() {
private val viewModel: LoginViewModel
get() = ViewModelProviders.of(this).get(LoginViewModel::class.java)
private val loadingFragment = LoadingDialogFragment()
var username = ""
var password = ""
private lateinit var loginButton: Button
lateinit var context: Context
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_login)
loginButton = findViewById(R.id.login_button)
loginButton.setOnClickListener {
username = login_username.text.toString().trim()
password = login_password.text.toString().trim()
viewModel.onLoginClicked(username, password.toMD5())
}
viewModel.loadingStatus.observe(this, Observer { value ->
value?.let { show ->
progress_bar_login.visibility = if (show) View.VISIBLE else View.GONE
}
})
viewModel.successfulAuthenticationStatus.observe(this, Observer { successfullyLogged ->
successfullyLogged?.let {
loadingFragment.setStyle(DialogFragment.STYLE_NORMAL, R.style.CustomLoadingDialogFragment)
if (successfullyLogged) {
loadingFragment.show(supportFragmentManager, "loadingFragment")
viewModel.onLoginPerformed()
} else {
login_password.text.clear()
login_password.isFocused
password = ""
}
}
})
viewModel.listsLoadingStatus.observe(this, Observer { loadingResult ->
loadingResult?.let {
when (loadingResult) {
COMPLETED -> {
val intent = Intent(this, MainActivity::class.java)
startActivity(intent)
setResult(Activity.RESULT_OK)
finish()
}
FAILED -> {
loadingFragment.changeText("Error")
loadingFragment.showProgressBar(false)
loadingFragment.showRetryButton(true)
}
}
}
})
viewModel.errorMessage.observe(this, Observer { value ->
value?.let { message ->
Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
viewModel.onToastShown()
}
})
}
Basically what I'm trying to do is to send username and password, show a progress bar while waiting for the result (if successful the logged user object is returned, otherwise a toast with the error message is shown), hide the progress bar and show the loading fragment. While showing the loading fragment start 3 async network calls and wait for their completion; when the third call is completed start the methods to elaborate the data and, when both done, start the next activity.
It seems to all works just fine, but debugging I've noticed the flow (basically network calls start/wait/onCompletion) is not at all like what I've described above. There's something to fix in the ViewModel, I guess, but I can't figure out what
I'm trying to learn how to use RxJava in Android, but have run into a dead end. I have the following DataSource:
object DataSource {
enum class FetchStyle {
FETCH_SUCCESS,
FETCH_EMPTY,
FETCH_ERROR
}
var relay: BehaviorRelay<FetchStyle> = BehaviorRelay.createDefault(FetchStyle.FETCH_ERROR)
fun fetchData(): Observable<DataModel> {
return relay
.map { f -> loadData(f) }
}
private fun loadData(f: FetchStyle): DataModel {
Thread.sleep(5000)
return when (f) {
FetchStyle.FETCH_SUCCESS -> DataModel("Data Loaded")
FetchStyle.FETCH_EMPTY -> DataModel(null)
FetchStyle.FETCH_ERROR -> throw IllegalStateException("Error Fetching")
}
}
}
I want to trigger an update downstream, whenever I change the value of relay, but this doesn't happen. It works when the Activity is initialized, but not when I'm updating the value. Here's my ViewModel, from where I update the value:
class MainViewModel : ViewModel() {
val fetcher: Observable<UiStateModel> = DataSource.fetchData().replay(1).autoConnect()
.map { result -> UiStateModel.from(result) }
.onErrorReturn { exception -> UiStateModel.Error(exception) }
.startWith(UiStateModel.Loading())
.subscribeOn(Schedulers.io())
.observeOn(Schedulers.io())
fun loadSuccess() {
DataSource.relay.accept(DataSource.FetchStyle.FETCH_SUCCESS)
}
fun loadEmpty() {
DataSource.relay.accept(DataSource.FetchStyle.FETCH_EMPTY)
}
fun loadError() {
DataSource.relay.accept(DataSource.FetchStyle.FETCH_ERROR)
}
}
This is the code from the Activity that does the subsciption:
model.fetcher
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({
uiState -> mainPresenter.loadView(uiState)
})
Ended up using kotlin coroutines instead, as I was unable to re-subscribe to ConnectableObservable and start a new fetch.
Here's the code for anyone interested.
The presenter:
class MainPresenter(val view: MainView) {
private lateinit var subscription: SubscriptionReceiveChannel<UiStateModel>
fun loadSuccess(model: MainViewModel) {
model.loadStyle(DataSource.FetchStyle.FETCH_SUCCESS)
}
fun loadError(model: MainViewModel) {
model.loadStyle(DataSource.FetchStyle.FETCH_ERROR)
}
fun loadEmpty(model: MainViewModel) {
model.loadStyle(DataSource.FetchStyle.FETCH_EMPTY)
}
suspend fun subscribe(model: MainViewModel) {
subscription = model.connect()
subscription.subscribe { loadView(it) }
}
private fun loadView(uiState: UiStateModel) {
when(uiState) {
is Loading -> view.isLoading()
is Error -> view.isError(uiState.exception.localizedMessage)
is Success -> when {
uiState.result != null -> view.isSuccess(uiState.result)
else -> view.isEmpty()
}
}
}
fun unSubscribe() {
subscription.close()
}
}
inline suspend fun <E> SubscriptionReceiveChannel<E>.subscribe(action: (E) -> Unit) = consumeEach { action(it) }
The view:
...
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
launch(UI) {
mainPresenter.subscribe(model)
}
btn_load_success.setOnClickListener {
mainPresenter.loadSuccess(model)
}
btn_load_error.setOnClickListener {
mainPresenter.loadError(model)
}
btn_load_empty.setOnClickListener {
mainPresenter.loadEmpty(model)
}
}
override fun onDestroy() {
super.onDestroy()
Log.d("View", "onDestroy()")
mainPresenter.unSubscribe()
}
...
The model:
class MainViewModel : ViewModel() {
val TAG = this.javaClass.simpleName
private val stateChangeChannel = ConflatedBroadcastChannel<UiStateModel>()
init {
/** When the model is initialized we immediately start fetching data */
fetchData()
}
override fun onCleared() {
super.onCleared()
Log.d(TAG, "onCleared() called")
stateChangeChannel.close()
}
fun connect(): SubscriptionReceiveChannel<UiStateModel> {
return stateChangeChannel.openSubscription()
}
fun fetchData() = async {
stateChangeChannel.send(UiStateModel.Loading())
try {
val state = DataSource.loadData().await()
stateChangeChannel.send(UiStateModel.from(state))
} catch (e: Exception) {
Log.e("MainModel", "Exception happened when sending new state to channel: ${e.cause}")
}
}
internal fun loadStyle(style: DataSource.FetchStyle) {
DataSource.style = style
fetchData()
}
}
And here's a link to the project on github.
I'm using Room + LiveData in my Android project. Following to Google Blueprints, I've implemented data layer of my application.
This is how my Dao looks like:
#Query("SELECT * FROM events WHERE id=:arg0")
fun loadSingle(id: String): LiveData<Event>
I'm calling it from my EventRepository:
fun loadSingle(eventId: String): LiveData<RequestReader<Event>> {
return object: NetworkManager<Event, Event>(appExecutors!!) {
override fun loadLocal(): LiveData<Event> {
val item = eventLocal!!.loadSingle("Title 1")
Crashlytics.log(Log.VERBOSE, TAG, "loadFromServer::loadLocal=$item")
return item
}
override fun isUpdateForced(data: Event?): Boolean {
Crashlytics.log(Log.VERBOSE, TAG, "loadFromServer::isUpdateForced")
return data == null || requestTimeout.isAllowed(UNDEFINED_KEY.toString())
}
override fun makeRequest(): LiveData<ApiResponse<Event>> {
Crashlytics.log(Log.VERBOSE, TAG, "loadFromServer::makeRequest")
return Database.createService(EventRemote::class.java).load(eventId)
}
override fun onSuccess(item: Event) {
eventLocal?.save(item)
}
override fun onFail() {
Crashlytics.log(Log.VERBOSE, TAG, "loadFromServer::onFail")
requestTimeout.reset(UNDEFINED_KEY.toString())
}
}.liveData
}
Where NetworkManager class is (has been "taken" from here):
abstract class NetworkManager<ResultType, RequestType> #MainThread constructor(val appExecutors: AppExecutors) {
companion object {
private val TAG = "TAG_NETWORK_MANAGER"
}
val liveData: MediatorLiveData<RequestReader<ResultType>> = MediatorLiveData()
init {
liveData.value = RequestReader.loading(null)
val localSource: LiveData<ResultType> = loadLocal()
Log.d(TAG, "before add::localSource=${localSource.value}")
liveData.addSource(localSource, { data ->
Log.d(TAG, "data=$data")
liveData.removeSource(localSource)
if (isUpdateForced(data)) {
loadRemote(localSource)
} else {
liveData.addSource(localSource, { reusedData -> liveData.value = RequestReader.success(reusedData)})
}
})
}
private fun loadRemote(localSource: LiveData<ResultType>) {
val remoteSource = makeRequest()
liveData.addSource(localSource, {
liveData.value = RequestReader.success(it)
})
liveData.addSource(remoteSource) { response ->
liveData.removeSource(localSource)
liveData.removeSource(remoteSource)
if (response!!.isSuccessful) {
appExecutors.diskIO.execute {
onSuccess(processResponse(response))
appExecutors.mainThread.execute {
liveData.addSource(localSource, {
liveData.value = RequestReader.success(it)
})
}
}
} else {
onFail()
liveData.addSource(localSource, {
liveData.value = RequestReader.error("Error: ${response.errorMessage}", it)
})
}
}
}
#MainThread
protected abstract fun loadLocal(): LiveData<ResultType>
#MainThread
protected abstract fun isUpdateForced(data: ResultType?): Boolean
#MainThread
protected abstract fun makeRequest(): LiveData<ApiResponse<RequestType>>
#WorkerThread
protected abstract fun onSuccess(item: RequestType)
#MainThread
protected abstract fun onFail()
#WorkerThread
protected fun processResponse(response: ApiResponse<RequestType>): RequestType {
return response.body!!
}
}
And after i expect to get my LiveData in ViewModel:
open class EventSingleViewModel: ViewModel(), RepositoryComponent.Injectable {
companion object {
private val TAG = "TAG_EVENT_SINGLE_VIEW_MODEL"
}
#Inject lateinit var eventRepository: EventRepository
var eventSingle: LiveData<RequestReader<Event>>? = null
override fun inject(repositoryComponent: RepositoryComponent) {
repositoryComponent.inject(this)
eventSingle = MutableLiveData<RequestReader<Event>>()
}
fun load(eventId: String) {
Crashlytics.log(Log.VERBOSE, TAG, "starts to loadList::eventId=$eventId")
eventSingle = eventRepository.loadSingle(eventId)
}
}
The problem.
I'm getting a list of events the same way (it works!) I've described above, but with a single event (this event is already in database) it doesn't work. I've found out that localSource.value is null (in NetworkManager). Maybe my query is bad or.. something else.
Check again your DAO implementation, the argument must be the same in both, the function parameter and the annotation arg.
Change this:
#Query("SELECT * FROM events WHERE id=:arg0")
fun loadSingle(id: String): LiveData<Event>
To:
#Query("SELECT * FROM events WHERE id=:id ")
fun loadSingle(id: String): LiveData<Event>