I have a single activity and multiple fragments styled application using the navigation component.
I am using Koin for my DI. I was wanting to create a Navigator class in my application as per the postulates of clean architecture.
This hypothetical class would look like :
class Navigator(private val navHostFragment: NavHostFragment)
{
fun toStudentsProfile():Unit
{
val action = HomeFragmentDirections.toStudentsProfile()
navHostFragment.findNavController().navigate(action)
}
fun toTeachersProfile():Unit
{
val action = HomeFragmentDirections.toTeachersProfile()
navHostFragment.findNavController().navigate(action)
}
}
My problem now is how should I create this under the Koin container ?
val platformModule = module {
single { Navigator("WHAT CAN BE DONE HERE") }
single { Session(get()) }
single { CoroutineScope(Dispatchers.IO + Job()) }
}
Furthermore, the Koin component would get ready before the navhostfragment is ready hence it won't be able to satisfy the dependency, to begin with.
Is there a way to provide Koin with an instance of a class and then subsequently start using it?
Koin allows to use parameters on injection
val platformModule = module {
factory { (navHostFragment: NavHostFragment) -> Navigator(navHostFragment) }
single { Session(get()) }
single { CoroutineScope(Dispatchers.IO + Job()) }
}
I have declared the dependency as factory, i guess it could be scoped to the activity as well. Declaring it as single will lead to misbehavior, as if the activity (therefore the navhostFragment) is re-created, the Navigator object will be referencing the destroyed navhostFragment.
As the fragments will be navhostFragment children, you can obtain the Navigator object in the fragments this way:
val navigator: Navigator by inject { parametersOf(requireParentFragment()) }
Related
I'm maintaining a large app (mostly) using a "one feature one activity"-architecture.
Now i'd like to scope a usecase, so it lives as long as the activity, something like this:
// koin module
scope<MyFeatureActivity> {
viewModel { MyFeatureActivityViewModel() }
viewModel { MyFeatureFragmentAViewModel(usecase = get()) }
viewModel { MyFeatureFragmentBViewModel(usecase = get()) }
scoped { MyFeatureUseCase() }
}
// fragments
class FeatureAFragment: AppCompatDialogFragment(){
private val viewModel by viewModel<MyFeatureFragmentAViewModel>()
....
}
// activity
class MyFeatureActivity : ScopeActivity() { ... }
However, this doesn't work. When launching MyFeatureFragmentA from MyFeatureActivity it's throwing an Exception:
org.koin.core.error.NoBeanDefFoundException:
|- No definition found for class:'MyFeatureAViewModel'. Check your definitions!
What am i doing wrong?
Please note: I would not like to just skip scopes and make the usecase a single (or a factory), since it actually stores some data relevant to only this activity: The data should be kept while we're in this feature, but dismissed when leaving it.
I have a repository where a chain of network requests is calling. The repository is accessed from the interactor. And interactor is accessed from viewModel. The view model is attached to activity A. If I go to activity B, which has its own viewModel, then the request chain in the repository of activity A does not complete its execution.
Is it possible to make a repository whose life cycle will be equal to the life cycle of the application. I need all requests to complete even if I go to a new activity.
Please, help me.
This is covered in the Coroutines guide on developer.android.com
class ArticlesRepository(
private val articlesDataSource: ArticlesDataSource,
private val externalScope: CoroutineScope,
private val defaultDispatcher: CoroutineDispatcher = Dispatchers.Default
) {
// As we want to complete bookmarking the article even if the user moves
// away from the screen, the work is done creating a new coroutine
// from an external scope
suspend fun bookmarkArticle(article: Article) {
externalScope.launch(defaultDispatcher) {
articlesDataSource.bookmarkArticle(article)
}
.join() // Wait for the coroutine to complete
}
}
Here externalScope is defined like this (for a scope with application lifetime):
class MyApplication : Application() {
// No need to cancel this scope as it'll be torn down with the process
val applicationScope = CoroutineScope(SupervisorJob() + otherConfig)
}
You should create a singleton Repository class, then access its instance anywhere you want.
object Repository {
val instance: Repository
get() {
return this
}
}
You can create create its object in ViewModel for A and create object in ViewModel for B.
Both will have same instance for Repository class, so in this way you can achieve what you need.
Is there any way to implement Dagger's SubCompoent concept on Koin?
The thing that i want to do is using instance from parent scope's one.
app_modules.kt
val favoriteModule = module {
scope(named<FavoriteFragment>()) {
scoped { GetFavoriteMovies(get()) }
scoped { FavoriteVMFactory(get(), get()) } // This need 'MovieEntityMovieMapper'
}
}
val popularModule = module {
scope(named<PopularFragment>()) {
scoped { GetPopularMovies(get()) }
scoped { PopularVMFactory(get(), get()) } // This need 'MovieEntityMovieMapper'
}
}
val searchModule = module {
scope(named<SearchFragment>()) {
scoped { SearchMovies(get()) }
scoped { SearchVMFactory(get(), get()) } // This need 'MovieEntityMovieMapper'
}
}
val mainModule = module {
scope(named<MainActivity>()) {
scoped { MovieEntityMovieMapper() }
// this ImageLoader also injected by Fragments
scoped<ImageLoader> { (activity: Activity) -> GlideImageLoader(activity) }
}
}
Using Dagger, this can be done by SubComponent or Component Dependency.
But in Koin(especially 2.0), i cant not find way.
Some answer said use
GlobalContext.get().koin.getScope("Parent").get<>().
https://github.com/InsertKoinIO/koin/issues/513
Koin sharing instances between modules
but i dont think it's not a clean approach and a dependency injection.
You can try https://github.com/beyama/winter which is inspired by Koin but has child graphs that can be used like Dagger's subcomponents. Winter has been used in production for some major apps with several million installs for a few years now. I hope it is ok to post an example here: https://play.google.com/store/apps/details?id=de.prosiebensat1digital.seventv
Disclaimer: I know the author and have been using his library myself since its release. So far it has been stable in my experience.
we are using in our project KOIN like DI library.
in some cases, when ViewModel instance not refreshing when Koin context is killing and recreating again. We need to implement feature like 'reassembling dependency graph in runtime', and this issue very critical for us.
I have ViewModel module like this:
object ViewModelModule {
val module by lazy {
module {
viewModel { AppLauncherViewModel(get(), get(), get(), get()) }
viewModel { AuthLoginPasswordViewModel(get(), get()) }
viewModel { SettingsViewModel(get(), get()) }
// some others
}
}
}
And my graph is assembling in android application by this way:
private fun assembleGraph() {
val graph = listOf(
AppModule.module,
StorageModule.module,
DatabaseConfigModule.module,
RepositoryModule.module,
InteractorModule.module,
ViewModelModule.module
)
application.startKoin(application, platformGraph)
}
fun reassembleGraph() {
stopKoin()
assembleGraph()
}
And when reassembleGraph() is calling - all good, another instances in graph are refreshing, but ViewModels, that injected in activity - are not, and they are keeping old references. I guess, that viewmodel is attached to activity lifecycle, and could help activity recreation, but i think it's not the best solution.
Has anyone the same problems? And help me please with advice, how to solve it, please.
You can do it with the use of scope in KOIN.
1) Define your ViewModels in scope
scope(named("ViewModelScope")){
viewModel {
AppLauncherViewModel(get(), get(), get(), get())
AuthLoginPasswordViewModel(get(), get())
SettingsViewModel(get(), get())
}
}
2) Create that particular scope with the use of below line in your application class.
val viewModelScope = getKoin().getOrCreateScope("ViewModelScope")
Above code is used to get ViewModel. And when you want to recreate scope you just need to close scope and recreate again. To close scope use below code.
val viewModelScopeSession = getKoin().getOrCreateScope("ViewModelScope")
viewModelScopeSession.close()
Once the scope is closed then after whenever you request to create or get scope at that time it will return new instance as per your requirement.
For further reference, you can see below link (8th Point).
Koin documentation
I am using Koin di library in my project. Version of lib is 1.0.0-RC-1.
My module:
val appModule = module {
scope("UserScope") { UserToaster(androidContext()) as Toaster }
scope("AnonScope") { AnonToaster(androidContext()) as Toaster }
}
I started koin in my Application class and created scope:
override fun onCreate() {
super.onCreate()
startKoin(this, listOf(appModule))
getKoin().getOrCreateScope("AnonScope")
}
And next I tried to inject implementation of Toaster from current scope to variable in Activity. Here the code:
private val toaster: Toaster by inject(scope = "AnonScope")
After this I got an error:
Caused by: org.koin.error.DependencyResolutionException: Multiple definitions found for type 'interface com.example.nkirilov.playground.Toaster (Kotlin reflection is not available)' - Koin can't choose between :
Scope [name='UserScope',class='com.example.nkirilov.playground.Toaster']
Scope [name='AnonScope',class='com.example.nkirilov.playground.Toaster']
Check your modules definition, use inner modules visibility or definition names.
I do not understand why this does not work (If use single with different names - it will work). Is that koin bug? How to avoid this error?
I implemented it like this
Module:
val navigationModule = module {
scope(DI.APP_SCOPE) { ClassA().create }
scope(DI.APP_SCOPE) { get(scopeId = DI.APP_SCOPE).classB }
scope(DI.APP_SCOPE) { get(scopeId = DI.APP_SCOPE).classC }
}
val authModule = module {
scope(DI.AUTH_SCOPE) { ClassA.create(ChildClassB(get(scopeId = DI.APP_SCOPE))) }
scope(DI.AUTH_SCOPE) { get(scopeId = DI.AUTH_SCOPE).classB }
scope(DI.AUTH_SCOPE) { get(scopeId = DI.AUTH_SCOPE).classC }
}
Main Activity:
private val classC: ClassC by inject(scope = getKoin().getOrCreateScope(APP_SCOPE))
AuthActivity:
private val classC: ClassC by inject(scope = getKoin().getOrCreateScope(DI.AUTH_SCOPE))
your definitions have the same name in Koin. Current version (~1.0.*) avoid you to specify which scope to use, by automating resolving a type and it's session id.
Can you avoid describe your definitions with same type, like:
val appModule = module {
scope("UserScope") { UserToaster(androidContext()) }
scope("AnonScope") { AnonToaster(androidContext()) }
}
Else we would need a feature to specify which scope to use when resolving a type. You would resolve it with:
val userScope = getScope("UserScope")
get<Toaster>(scope = userScope)