i'm making an app and i want to separate my UI logic into multiple UI classes with BaseUi class being lifecycle aware. I'm using Kodein as my DI and i have an issue with fragment.viewLifecycleOwnerLiveData.observe not being called when instance of my ui class is being retrieved by Kodein.
Here is my Fragment class:
class ListFragment : Fragment(), DIAware {
override val di: DI by closestDI()
override val diTrigger: DITrigger = DITrigger()
private var binding: FragmentMoviesBinding? = null
private val fragmentBinding get() = binding
private val kodeinMoviesUi: MoviesUi by instance() //fragment does not observe viewLifecycleOwnerLiveData
private val moviesUi: MoviesUi = MoviesUi(this) //fragment now observe viewLifecycleOwnerLiveData
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding = FragmentMoviesBinding.inflate(inflater, container, false)
return binding?.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
diTrigger.trigger()
}
override fun onDestroyView() {
super.onDestroyView()
binding = null
}
}
BaseUi class:
abstract class BaseUi<F : Fragment>(private val fragment: F) : LifecycleObserver {
init {
fragment.viewLifecycleOwnerLiveData.observe(fragment, { subscribeToLifecycle() })
}
private fun subscribeToLifecycle() {
fragment.viewLifecycleOwner.lifecycle.addObserver(object : LifecycleObserver {
#OnLifecycleEvent(Lifecycle.Event.ON_CREATE)
fun onCreate() {
onViewCreated()
}
})
}
abstract fun onViewCreated()
}
And UiModule:
val uiModule = DI.Module("uiModule") {
bind<ListFragment>() with provider { ListFragment() }
bind<MoviesUi>() with provider { MoviesUi(instance()) }
}
Cross post from https://github.com/Kodein-Framework/Kodein-DI/issues/353
Here is your problem bind<ListFragment>() with provider { ListFragment() }.
You bound the ListFragment with a provider, meaning every time you ask to the container it will create an instance of ListFragment. So, when you inject MoviesUi with private val kodeinMoviesUi: MoviesUi by instance(), it gets another instance of ListFragment.
I suggest that you define the binding for MoviesUi as a factory, waiting to receive a ListFragment instance:
bind<MoviesUi>() with factory {fragment: ListFragment -> MoviesUi(fragment) }
then you can inject it in the ListFragment like:
private val kodeinMoviesUi: MoviesUi by instance(args = this)
Related
Well I am a beginner with android and kotlin so I have been trying to send a variable semesterSelected from the fragment ViewCourses to my viewmodel UserViewModel is the codes are down below.
`class ViewCourses(path: String) : ReplaceFragment() {
private var semesterSelected= path
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
container?.removeAllViews()
return inflater.inflate(R.layout.fragment_view_courses, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
userRecyclerView = view.findViewById(R.id.recyclerView)
userRecyclerView.layoutManager = LinearLayoutManager(context)
userRecyclerView.setHasFixedSize(true)
adapter = MyAdapter()
userRecyclerView.adapter = adapter
makeToast(semesterSelected)
// The variable I am trying to send to UserViewModel is -->> semesterSelected
var viewModel: UserViewModel = ViewModelProvider(this)[UserViewModel::class.java]
viewModel.allUsers.observe(viewLifecycleOwner) {
adapter.updateUserList(it)
}
}
}
class UserViewModel : ViewModel() {
private val repository: UserRepository = UserRepository("CSE/year3semester1").getInstance()
private val _allUsers = MutableLiveData<List<CourseData>>()
val allUsers: LiveData<List<CourseData>> = _allUsers
init {
repository.loadUsers(_allUsers)
}
}
The reason I am doing this is I am wanting a to send a variable to my repository UserRepository all the way from ViewCourses and thought sending this via UserViewModel might be a way .
class UserRepository(semesterSelected: String) {
// The variable I am expecting to get from UserViewModel
private var semesterSelected = semesterSelected
private val databaseReference: DatabaseReference =
FirebaseDatabase.getInstance().getReference("course-list/$semesterSelected")
#Volatile
private var INSTANCE: UserRepository? = null
fun getInstance(): UserRepository {
return INSTANCE ?: synchronized(this) {
val instance = UserRepository(semesterSelected)
INSTANCE = instance
instance
}
}
fun loadUsers(userList: MutableLiveData<List<CourseData>>) {
databaseReference.addValueEventListener(object : ValueEventListener {
override fun onDataChange(snapshot: DataSnapshot) {
try {
val courseList: List<CourseData> = snapshot.children.map { dataSnapshot ->
dataSnapshot.getValue(CourseData::class.java)!!
}
userList.postValue(courseList)
} catch (e: Exception) {
}
}
override fun onCancelled(error: DatabaseError) {
}
})
}
}
I tried something like below
class ViewCourses(path: String) : ReplaceFragment() {
private var semesterSelected= path
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
container?.removeAllViews()
return inflater.inflate(R.layout.fragment_view_courses, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
userRecyclerView = view.findViewById(R.id.recyclerView)
userRecyclerView.layoutManager = LinearLayoutManager(context)
userRecyclerView.setHasFixedSize(true)
adapter = MyAdapter()
userRecyclerView.adapter = adapter
makeToast(semesterSelected)
**// Sending the variable as parameter**
var viewModel: UserViewModel = ViewModelProvider(this)[UserViewModel(semesterSelected)::class.java]
viewModel.allUsers.observe(viewLifecycleOwner) {
adapter.updateUserList(it)
}
}
}
class UserViewModel(semesterSelected: String) : ViewModel() {
private val repository: UserRepository = UserRepository("CSE/year3semester1").getInstance()
private val _allUsers = MutableLiveData<List<CourseData>>()
val allUsers: LiveData<List<CourseData>> = _allUsers
init {
repository.loadUsers(_allUsers)
}
}
but doing this my app crashes . how can this be done ?
Thanks in Advance.
var viewModel: UserViewModel = ViewModelProvider(this)[UserViewModel(semesterSelected)::class.java]
UserViewModel(semesterSelected)::class.java NOR UserViewModel::class.java is a constructor for the view model.
If you would want to have ViewModel with that NEEDS initial parameters, you will have to create your own factory for that - which is a tad more complicated and for your case, it might be overkill for what you are trying to do but in the longterm it will pay off(Getting started with VM factories).
With that said, your needs can be easily solved by one function to initialize the view model.
class UserViewModel() : ViewModel() {
private lateinit var repository: UserRepository
private val _allUsers = MutableLiveData<List<CourseData>>()
val allUsers: LiveData<List<CourseData>> = _allUsers
fun initialize(semesterSelected: String) {
repository = UserRepository("CSE/year3semester1").getInstance()
repository.loadUsers(_allUsers)
}
}
A ViewModel must be created using a ViewModelProvider.Factory. But there is a default Factory that is automatically used if you don't specify one. The default factory can create ViewModels who have constructor signatures that are one of the following:
empty, for example MyViewModel: ViewModel.
saved state handle, for example MyViewModel(private val savedStateHandle: SavedStateHandle): ViewModel
application, for example MyViewModel(application: Application): AndroidViewModel(application)
both, for example MyViewModel(application: Application, private val savedStateHandle: SavedStateHandle): AndroidViewModel(application)
If your constructor doesn't match one of these four above, you must create a ViewModelProvider.Factory that can instantiate your ViewModel class and use that when specifying your ViewModelProvider. In Kotlin, you can use by viewModels() for easier syntax. All the instructions for how to create your ViewModelFactory are here.
LiveData is not observing on child viewpager fragments where the child fragments have one shared viewmodel to access data.
Here FragmentA and FragmentB are part of a viewpager and both of them are sharing one viemodel SharedViewModel.
public class SharedViewModel extends AndroidViewModel { //in Java
private final MutableLiveData<Data> mLiveData = new MutableLiveData<>();
public LiveData<Data> getLiveData() {
return mLiveData;
}
//for updating data through LiveData, using post as and when I get the response from DataSource as shown below.
mLiveData.postValue(response); //getting the response on debugging
}
class FragmentA : Fragment() { //in Kotlin
override fun onCreate(#Nullable savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
mViewModel = ViewModelProvider(this).get(SharedViewModel::class.java)
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
....
mViewModel.liveData.observe(viewLifecycleOwner, {
//no call coming in this block so unable to update view
})
}
}
class FragmentB : Fragment() { //in Kotlin
override fun onCreate(#Nullable savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
mViewModel = ViewModelProvider(this).get(SharedViewModel::class.java)
}
}
Need some help as to why the live data is not able to observe the changes.
Thanks in advance.
Your ViewModel is not shared. you have named it as sharedViewmodel but the way you are getting an instance of it by passing a Unique Owner it will also be a unique instance.
the correct way of sharing view model is
class SharedViewModel : ViewModel() {
private val myLiveData = MutableLiveData<Data>()
fun getMyLiveDta():LiveData {
return myLiveData
}
}
Now in the first fragment
class MasterFragment : Fragment() {
private lateinit var itemSelector: Selector
// Get instance of viewmodel in fragment like this
private val model: SharedViewModel by activityViewModels()
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
}
}
And in the second fragment like this
class DetailFragment : Fragment() {
private val model: SharedViewModel by activityViewModels()
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
model.selected.observe(viewLifecycleOwner, Observer<Item> { item ->
// Update the UI
})
}
}
I have a parent fragment which fetches a list from API using ViewModel and Retrofit, the ViewModel is injected with Hilt.
After the list gets fetched the parent fragment will pass to its child fragment that is inside of parent fragment.
but the problem is that ViewModel is instantiated one more time in the child fragment.
Parent Fragment
#AndroidEntryPoint
class ParentFragment : Fragment() {
override val mViewModel: URLViewModel by viewModels()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
mViewBinding = getViewBinding(inflater, container)
mViewModel.liveData.observe(this, { data ->
{
childFragmentManager.beginTransaction().apply {
replace(
mViewBinding.fragmentContainer.id,
ChildFragment(data)
)
}
commit()
} })
mViewModel.getURL("TEST", "2021-06-18", "2021-07-18", 1 , 0 , -1, false)
return mViewBinding.root
}
}
ChildFragment
#AndroidEntryPoint
class ChildFragment(val data: List<Item>) : Fragment() {
override val mViewModel: URLViewModel by viewModels()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
mViewBinding = getViewBinding(inflater, container)
// mViewModel is instantiated again and some all strings properties of it is null.
return mViewBinding.root
}
}
URLViewModel
#HiltViewModel
class URLViewModel #Inject constructor(private val urlApi: URLApi): ViewModel() {
private val _urlLiveData = MutableLiveData<State<Any?>>()
val urlLiveData: LiveData<State<Any?>> = _urlLiveData
var urlName: String? = null
var beginDate: String? = null
var endDate: String? = null
var adultCount = 0
var childrenCount = 0
var airportId = 0
var isRoundTrip = false
init {
Log.e("URLViewModel", "iniialed again" )
}
#ExperimentalStdlibApi
fun getUrl(urlName: String, beginDate: String, endDate: String, adultCount: Int, childCount: Int, airportId: Int, isRoundTrip: Boolean){
Log.e("XXXXXX", "getUrl: called with url of " + urlName )
this.urlName = urlName
this.beginDate = beginDate
this.endDate = endDate
this.adultCount = adultCount
this.childrenCount = childCount
this.airportId = airportId
this.isRoundTrip = isRoundTrip
val mutableLiveData = MutableLiveData<State<Any?>>()
mutableLiveData.value = State.loading()
viewModelScope.launch {
val res = urlApi.getURL(urlName,beginDate,endDate,adultCount,childCount,airportId,isRoundTrip)
Log.e("URLVIewModel", "getUrl: response received" )
_urlLiveData.value = res
}
}
}
when I wanna access some properties like beginDate, they are null, because the ViewModel is instantiated again,
viewModels() delegation create view model against the same instance i.e Fragment's instance in your case. What you need to do is to create a shared View model .
There is helper delegate available for it with ktx libraries.
add the ktx dependency which you already have i guess from here.
implementation "androidx.fragment:fragment-ktx:1.3.4"
And create view model with
private val viewModel by activityViewModels<UrlViewModel>()
You do not have to use activity shared view model. Simply request view model from parent fragment in ChildFragment.
private val viewModel by viewModels<UrlViewModel>(ownerProducer = { requireParentFragment() })
You are trying to use share viewmodel. Try to following code for reference.
#AndroidEntryPoint
class ParentFragment : Fragment() {
private lateinit var viewModel: URLViewModel
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = ViewModelProvider(requireActivity()).get(URLViewModel::class.java)
}
}
#AndroidEntryPoint
class ChildFragment : Fragment() {
private lateinit var viewModel: URLViewModel
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = ViewModelProvider(requireActivity()).get(URLViewModel::class.java)
}
}
I'm using Dagger 2 in clean architecture project, I have 2 fragments. These 2 fragments should be scoped together to share the same instances, but unfortunately, I got empty object in the second fragment.
Application Component
#ApplicationScope
#Component(modules = [ContextModule::class, RetrofitModule::class])
interface ApplicationComponent {
fun exposeRetrofit(): Retrofit
fun exposeContext(): Context
}
Data layer - Repository
class MoviesParsableImpl #Inject constructor(var moviesLocalResult: MoviesLocalResult): MoviesParsable {
private val TAG = javaClass.simpleName
private val fileUtils = FileUtils()
override fun parseMovies() {
Log.d(TAG,"current thread is ".plus(Thread.currentThread().name))
val gson = Gson()
val fileName = "movies.json"
val jsonAsString = MyApplication.appContext.assets.open(fileName).bufferedReader().use{
it.readText()
}
val listType: Type = object : TypeToken<MoviesLocalResult>() {}.type
moviesLocalResult = gson.fromJson(jsonAsString,listType)
Log.d(TAG,"result size ".plus(moviesLocalResult.movies?.size))
}
override fun getParsedMovies(): Results<MoviesLocalResult> {
return Results.Success(moviesLocalResult)
}
}
Repo Module
#Module
interface RepoModule {
#DataComponentScope
#Binds
fun bindsMoviesParsable(moviesParsableImpl: MoviesParsableImpl): MoviesParsable
}
MoviesLocalResultsModule(the result need its instance across different fragments)
#Module
class MoviesLocalResultModule {
#DataComponentScope
#Provides
fun provideMovieLocalResults(): MoviesLocalResult{
return MoviesLocalResult()
}
}
Use case
class AllMoviesUseCase #Inject constructor(private val moviesParsable: MoviesParsable){
fun parseMovies(){
moviesParsable.parseMovies()
}
fun getMovies(): Results<MoviesLocalResult> {
return moviesParsable.getParsedMovies()
}
}
Presentation Component
#PresentationScope
#Component(modules = [ViewModelFactoryModule::class],dependencies = [DataComponent::class])
interface PresentationComponent {
fun exposeViewModel(): ViewModelFactory
}
First ViewModel, where I got the result to be shared with the other fragment when needed
class AllMoviesViewModel #Inject constructor(private val useCase: AllMoviesUseCase):ViewModel() {
private val moviesMutableLiveData = MutableLiveData<Results<MoviesLocalResult>>()
init {
moviesMutableLiveData.postValue(Results.Loading())
}
fun parseJson(){
viewModelScope.launch(Dispatchers.Default){
useCase.parseMovies()
moviesMutableLiveData.postValue(useCase.getMovies())
}
}
fun readMovies(): LiveData<Results<MoviesLocalResult>> {
return moviesMutableLiveData
}
}
Second ViewModel where no need to request data again as it's expected to be scoped
class MovieDetailsViewModel #Inject constructor(private val useCase: AllMoviesUseCase): ViewModel() {
var readMovies = liveData(Dispatchers.IO){
emit(Results.Loading())
val result = useCase.getMovies()
emit(result)
}
}
First Fragment, where data should be requested:
class AllMoviesFragment : Fragment() {
private val TAG = javaClass.simpleName
private lateinit var viewModel: AllMoviesViewModel
private lateinit var adapter: AllMoviesAdapter
private lateinit var layoutManager: LinearLayoutManager
private var ascendingOrder = true
#Inject
lateinit var viewModelFactory: ViewModelFactory
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setHasOptionsMenu(true)
DaggerAllMoviesComponent.builder()
.presentationComponent(
DaggerPresentationComponent.builder()
.dataComponent(
DaggerDataComponent.builder()
.applicationComponent(MyApplication.applicationComponent).build()
)
.build()
).build()inject(this)
viewModel = ViewModelProvider(this, viewModelFactory).get(AllMoviesViewModel::class.java)
startMoviesParsing()
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_all_movies, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
setupRecyclerView()
viewModel.readMovies().observe(viewLifecycleOwner, Observer {
if (it != null) {
when (it) {
is Loading -> {
showResults(false)
}
is Success -> {
showResults(true)
Log.d(TAG, "Data observed ".plus(it.data))
addMoviesList(it.data)
}
is Error -> {
moviesList.snack(getString(R.string.error_fetch_movies))
}
}
}
})
}
Second Fragment, where I expect to get the same instance request in First Fragment as they are scoped.
class MovieDetailsFragment: Fragment() {
val TAG = javaClass.simpleName
#Inject
lateinit var viewModelFactory: ViewModelFactory
lateinit var viewModel: MovieDetailsViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val depend = DaggerAllMoviesComponent.builder()
.presentationComponent(
DaggerPresentationComponent.builder()
.dataComponent(
DaggerDataComponent.builder()
.applicationComponent(MyApplication.applicationComponent).build())
.build()
).build()
depend.inject(this)
viewModel = ViewModelProvider(this, viewModelFactory).get(MovieDetailsViewModel::class.java)
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
viewModel.readMovies.observe(this, Observer {
if (it!=null){
Log.d(TAG,"Movies returned successfully")
}
})
return super.onCreateView(inflater, container, savedInstanceState)
}
}
Scopes tell a component to cache the results of a binding. It has nothing to do with caching instances of any components. As such, you are always creating a new DataComponent, PresentationComponent, and AllMoviesComponent in your fragments' onCreate methods.
In order to reuse the same AllMoviesComponent instance, you need to store it somewhere. Where you store it can depend on your app architecture, but some options include MyApplication itself, the hosting Activity, or in your navigation graph somehow.
Even after fixing this, you can't guarantee that parseMovies has already been called. The Android system could kill your app at any time, including when MoviesDetailFragment is the current fragment. If that happens and the user navigates back to your app later, any active fragments will be recreated, and you'll still get null.
I'm dev-ing activity using dagger. In my fragment, I can use this code as below. but when I use this code in activity, I cannot use this code.
private val viewModel by viewModels<NoticeViewModel> { viewModelFactory }
As result I can't initialize viewmodel. how can I initialize activity using dagger?
fragment
class NoticeFragment : DaggerFragment() {
#Inject
lateinit var viewModelFactory: ViewModelProvider.Factory
private val viewModel by viewModels<NoticeViewModel> { viewModelFactory }
private lateinit var viewDataBinding: FragmentNoticeBinding
private var notice = ""
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val view = inflater.inflate(R.layout.fragment_notice, container, false)
viewDataBinding = FragmentNoticeBinding.inflate(inflater, container, false).apply {
viewmodel = viewModel
}
return view
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
viewDataBinding.lifecycleOwner = this.viewLifecycleOwner
init()
viewModel.getNotice()
}
private fun init(){
viewModel.notice.observe(this, Observer{
noticeMain.text = it
})
}
}
activity
class ScheduleDialog : DaggerActivity() {
#Inject
lateinit var viewModelFactory: ViewModelProvider.Factory
private val viewModel by viewModels<ScheduleDialogViewModel> { viewModelFactory }
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_schedule_dialog)
//viewDataBinding = DataBindingUtil.setContentView( this,R.layout.activity_schedule_dialog)
viewModel.getScheduleById(5)
}
}
MyComponent component = DaggerMyComponent.builder().build();
component.inject(this);
For dependency injection you should have the following code, also in the component code should be
void inject(YourActivity activity);