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Android Architecture Design
With Koin
Arnaud Giuliani
@arnogiu
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Koin Project Lead
Google Dev Expert - Kotlin
@arnogiu
Arnaud GIULIANI
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Architecture Recipes
With Koin
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Koin Core Concepts π
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Just use Koin,
what else?
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class ClassA()
class ClassB(val a : ClassA)
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class ClassA()
class ClassB(val a : ClassA)
module {
}
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class ClassA()
class ClassB(val a : ClassA)
module {
single { ClassB() }
}
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class ClassA()
class ClassB(val a : ClassA)
module {
single { ClassA() }
single { ClassB(???) }
}
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class ClassA()
class ClassB(val a : ClassA)
module {
single { ClassA() }
single { ClassB(get()) }
}
- Constructor injection con
fi
gured via Koin DSL
- Instances are called by Koin Container
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class MyApp {
val classB : ClassB
}
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class MyApp : KoinComponent {
val classB : ClassB
}
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class MyApp : KoinComponent {
val classB by inject()
}
- Use the Koin API to retrieve a dependency
- Host class is not created by Koin
MyApp().classB
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Classical MVP-MVVM π―
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https:/
/github.com/InsertKoinIO/architecture-samples/tree/dev-koin
https:/
/github.com/android/architecture-samples
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Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksViewModel
TasksActivity
Tasks Database
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Since Koin 3.x!
// Android
implementation "io.insert-koin:koin-android:$koin_version"
implementation "io.insert-koin:koin-androidx-viewmodel:$koin_version"
implementation "io.insert-koin:koin-androidx-scope:$koin_version"
implementation "io.insert-koin:koin-androidx-fragment:$koin_version"
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Tasks DataSource
class TasksRemoteDataSource : TasksDataSource
// Koin DSL
single { TasksRemoteDataSource() }
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Tasks DataSource
Tasks Local DataSource
class TasksRemoteDataSource : TasksDataSource
class TasksLocalDataSource(
private val tasksDao: TasksDao,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksDataSource
// Koin DSL
single { TasksRemoteDataSource() }
single { TasksLocalDataSource(get(),get()) }
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Tasks DataSource
Tasks Local DataSource
class TasksRemoteDataSource : TasksDataSource
class TasksLocalDataSource(
private val tasksDao: TasksDao,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksDataSource
// Koin DSL
single(named("RemoteDS")) { TasksRemoteDataSource() }
single(named("LocalDS")) { TasksLocalDataSource(get(),get()) }
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class DefaultTasksRepository(
private val tasksRemoteDataSource: TasksDataSource,
private val tasksLocalDataSource: TasksDataSource,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksRepository
// Koin DSL
single {
DefaultTasksRepository(
get(),
get(),
get()
)
}
Tasks Repository
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class DefaultTasksRepository(
private val tasksRemoteDataSource: TasksDataSource,
private val tasksLocalDataSource: TasksDataSource,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksRepository
// Koin DSL
single {
DefaultTasksRepository(
get(named("RemoteDS")),
get(named("LocalDS")),
get()
)
}
Tasks Repository
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// Koin DSL
single {
Room.databaseBuilder(
androidContext().applicationContext,
ToDoDatabase::class.java,
"Tasks.db"
).build()
}
single { get().taskDao() }
Tasks Database
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// Koin DSL
single {
Room.databaseBuilder(
androidContext().applicationContext,
ToDoDatabase::class.java,
"Tasks.db"
).build()
}
single { get().taskDao() }
Tasks Database
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class TasksViewModel(
private val tasksRepository: TasksRepository,
private val savedStateHandle: SavedStateHandle
) : ViewModel()
// Koin DSL
viewModel { TasksViewModel(get(),get()) }
TasksViewModel
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// by ViewModel() in Activity & Fragment
class TasksActivity : AppCompatActivity() {
// also inject SavedStateHandle
val viewModel : TasksViewModel by viewModel()
}
TasksActivity
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Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksActivity
Tasks Database
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Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksPresenter
TasksActivity
Tasks Database
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class TasksPresenter(
private val tasksRepository: TasksRepository,
private val view: TasksView
)
// Koin DSL - Parameter injection for Presenter
factory { TasksPresenter(get(), ??? ) }
TasksViewPresenter
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class TasksPresenter(
private val tasksRepository: TasksRepository,
private val view: TasksView
)
// Koin DSL - Parameter injection for Presenter
factory { (view: TasksView) -> TasksPresenter(get(),view) }
TasksViewPresenter
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class TasksActivity : TasksView, AppCompatActivity() {
// inject itself as a view
val presenter : TasksPresenter by inject { parametersOf(this) }
}
TasksView
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val appModule = module {
// Presentation Layers
viewModel { TasksViewModel(get(),get()) }
factory { (view: TasksView) -> TasksPresenter(get(),view) }
// Repository
single {
DefaultTasksRepository(get(named("RemoteDS")),get(named("LocalDS")),get())
}
// Data Sources
single(named("RemoteDS")) { TasksRemoteDataSource() }
single(named("LocalDS")) { TasksLocalDataSource(get(),get()) }
// Room
single { Room.databaseBuilder(...).build() }
single { get().taskDao() }
}
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- Layers, features β¦
- Granularity & Testability
Organising Modules? π€
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val dataModule = module { }
val uiModule = module { }
val appModule = dataModule + uiModule
startKoin {
modules(appModule)
}
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Clean Architecture π
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No content
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Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksViewModel
TasksActivity
Tasks Database
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Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksViewModel
TasksActivity
Tasks Database
GetTaskUseCase
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class TasksViewModel(
private val getTaskUseCase: GetTaskUseCase,
private val savedStateHandle: SavedStateHandle
) : ViewModel()
// Koin DSL
viewModel { TasksViewModel(get(),get()) }
TasksViewModel
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class GetTaskUseCase(
private val tasksRepository: TasksRepository
)
// Koin DSL
// Donβt hold instance - ensure itβs stateless
factory { GetTaskUseCase(get()) }
GetTaskUseCase
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val appModule = module {
// Presentation Layers
viewModel { TasksViewModel(get(),get()) }
factory { (view: TasksView) -> TasksPresenter(get(),view) }
// Repository
single {
DefaultTasksRepository(get(named("RemoteDS")),get(named("LocalDS")),get())
}
// Data Sources
single(named("RemoteDS")) { TasksRemoteDataSource() }
single(named("LocalDS")) { TasksLocalDataSource(get(),get()) }
// Room
single { Room.databaseBuilder(...).build() }
single { get().taskDao() }
}
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val appModule = module {
// Presentation Layers
viewModel { TasksViewModel(get(),get()) }
factory { (view: TasksView) -> TasksPresenter(get(),view) }
// Usecase
factory { GetTaskUseCase(get()) }
// Repository
single {
DefaultTasksRepository(get(named("RemoteDS")),get(named("LocalDS")),get())
}
// Data Sources
single(named("RemoteDS")) { TasksRemoteDataSource() }
single(named("LocalDS")) { TasksLocalDataSource(get(),get()) }
// Room
single { Room.databaseBuilder(...).build() }
single { get().taskDao() }
}
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Letβs wrap up π
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Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksPresenter
TasksActivity
Tasks Database
TasksViewModel
Koin API
factory or viewModel
single
single
single
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Koin API
factory or viewModel
single
single
single
Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksViewModel
TasksActivity
Tasks Database
GetTaskUseCase
TasksPresenter
factory
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Koin API
factory or viewModel
single
single
single
Repository
DataSource Local DataSource
ViewModel
Android UI
Database
UseCase / Interactor
Presenter
factory
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Working with Scopes π
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Why do we need a scope?
π¦ keep instances
β± specific time
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What about Android scope?
We maintain instances for the duration of
an Android component lifecycle.
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Follow the Android Components
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class MyActivity : AppCompatActivity() {
val myPresenter : MyPresenter by inject()
}
// Koin DSL
factory { MyPresenter(...) }
π₯
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Android Scope
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class MyActivity : ScopeActivity() {
// Resolved in MyActivity's scope
val myPresenter : MyPresenter by inject()
val myAdapter : MyAdapter by inject()
}
// Koin DSL
scope {
scoped { MyPresenter() }
scoped { MyAdapter(get()) }
}
class MyAdapter(val presenter : Mypresenter)
π₯
ScopeActivity use Activityβs scope
by default
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ViewModel
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class MyActivity : Activity() {
val myViewModel : MyViewModel by viewModel()
}
// Koin DSL
viewModel { MyViewModel() }
β»
class MyViewModel() : ViewModel()
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class MyActivity : ScopeActivity() {
// Override current scope to Activity's scope by default
override val scope : Scope by activityRetainedScope()
val myViewModel : MyViewModel by viewModel()
val myAdapter : MyAdapter by inject()
}
All components are
backed
By ViewModel β
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Navigation Graph ViewModel
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// Android Nav
implementation βio.insert-koin:koin-androidx-navigation:$koin_version"
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class NavViewModel() : ViewModel()
// Koin DSL
viewModel { NavViewModel() }
NavViewModel
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class MyFragment : Fragment() {
val navViewModel : NavViewModel by koinNavGraphViewModel(R.id.nav_graph)
}
MyFragment Nav Graph
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Scopes - Wrap up π
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// Koin DSL
scope {
scoped { MyPresenter() }
scoped { MyAdapter(get()) }
}
Define a scope
class MyActivity : ScopeActivity() {
}
interface AndroidScopeComponent {
override val scope : Scope by activityScope()
}
Use a scope with Android API
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// create scope
getKoin().createScope(...)
// ... get it elsewhere
val scope = getKoin().getScope(...)
scope.get<>()
Get the Scope API
class MyFragment : Fragment() {
val navViewModel : NavViewModel by koinNavGraphViewModel(R.id.nav_graph)
}
ViewModel scoped to Nav Graph
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Koin API
factory or viewModel
single
single
single
Repository
DataSource Local DataSource
ViewModel
Android UI
Database
Presenter
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Koin API
factory, viewModel or Scope
single
single
single
Repository
DataSource Local DataSource
ViewModel
Android UI
Database
Presenter
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Keep your Koin con
fi
g simple β¨
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Less Code = Less Bugs
Chet Haase
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New Architectures! π¦
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Jetpack Compose π¦
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Injecting in Compose
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// Android Nav
implementation βio.insert-koin:koin-androidx-compose:$koin_versionβ
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// Retrieving instance in a composable
@Composable
fun App() {
val myService = get()
// or by inject()
}
Getting instances in a Composable
// Default parameter value
@Composable
fun App(myService: MyService = get()) {
}
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// Retrieving ViewModel in a composable
@Composable
fun App() {
val myViewModel = getViewModel()
// or by viewModel()
}
Getting ViewModel in a Composable
// Default parameter value
@Composable
fun App(myViewModel: MyViewModel = getViewModel()) {
}
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https:/
/github.com/InsertKoinIO/compose-samples
Jetpack Compose Samples
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Koin API
factory or viewModel
single
single
single
Repository
DataSource Local DataSource
ViewModel
Android UI
Database
Presenter
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Koin API
factory or viewModel
single
single
single
Repository
DataSource Local DataSource
ViewModel
Composable
Database
Presenter
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Dependency Injection
For Kotlin Multiplatform β
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No content
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Repository
DataSource Local DataSource
Presentation
Android UI
Database
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Repository
DataSource Local DataSource
Native UI (Android, iOS)
Database
Presentation
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Shared
Kotlin Common
Repository
DataSource Local DataSource
Native UI (Android, iOS)
Database
Presentation
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People In Space
https:/
/github.com/joreilly/PeopleInSpace
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No content
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Android App
Common Code
iOS App
Backend & web app
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Common Code
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Common DI Modules
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Kermit Logging
Json Serialization
Ktor Http Client
+ API Component
Data Repository
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Json Serialization
Ktor Http Client
+ API Component
Data Repository
Kermit Logging
=> Data Storage with SQLDelight
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No content
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JVM Impl
iOS Impl
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val appModule = module {
viewModel { PeopleInSpaceViewModel(get()) }
}
ViewModel -> Repository
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Koin API
factory or viewModel
single
single
single
Kotlin Multiplatform API π
Repository
DataSource Local DataSource
Native UI (Android, iOS)
Database
Presentation
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New features! π
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New Feature Proposal β¨
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Limits of Koin DSL
π€¨
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Kotlin Compiler Plugin! π
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KSP Powered π₯
π Generate Koin stu
ff
DSL for you
https:/
/github.com/google/ksp
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Koin Semantic π€
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koin_annotations_version = β1.0.0-beta-2β
implementation "io.insert-koin:koin-annotations:$koin_ksp_version"
ksp "io.insert-koin:koin-ksp-compiler:$koin_ksp_version"
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Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksViewModel
TasksActivity
Tasks Database
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De
fi
nitions
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Tasks DataSource
class TasksRemoteDataSource : TasksDatasource
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Tasks DataSource
@Single
class TasksRemoteDataSource : TasksDatasource
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Tasks DataSource
Tasks Local DataSource
class TasksRemoteDataSource : TasksDatasource
class TasksLocalDataSource(
private val tasksDao: TasksDao,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksDatasource
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Tasks DataSource
Tasks Local DataSource
@Single
class TasksRemoteDataSource : TasksDatasource
@Single
class TasksLocalDataSource(
private val tasksDao: TasksDao,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksDatasource
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Tasks DataSource
Tasks Local DataSource
@Single
@Named("RemoteDS")
class TasksRemoteDataSource : TasksDatasource
@Single
@Named("LocalDS")
class TasksLocalDataSource(
private val tasksDao: TasksDao,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksDatasource
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class DefaultTasksRepository(
private val tasksRemoteDataSource: TasksDataSource,
private val tasksLocalDataSource: TasksDataSource,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksRepository
Tasks Repository
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@Single
class DefaultTasksRepository(
private val tasksRemoteDataSource: TasksDataSource,
private val tasksLocalDataSource: TasksDataSource,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksRepository
Tasks Repository
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@Single
class DefaultTasksRepository(
@Named("RemoteDS")
private val tasksRemoteDataSource: TasksDataSource,
@Named("LocalDS")
private val tasksLocalDataSource: TasksDataSource,
private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) : TasksRepository
Tasks Repository
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class TasksViewModel(
private val tasksRepository: TasksRepository,
private val savedStateHandle: SavedStateHandle
) : ViewModel()
TasksViewModel
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@KoinViewModel
class TasksViewModel(
private val tasksRepository: TasksRepository,
private val savedStateHandle: SavedStateHandle
) : ViewModel()
TasksViewModel
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// by ViewModel() in Activity & Fragment
class TasksActivity : AppCompatActivity() {
// also inject SavedStateHandle
val viewModel : TasksViewModel by viewModel()
}
TasksActivity
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class TasksPresenter(
private val tasksRepository: TasksRepository,
private val view: TasksView
)
TasksViewPresenter
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@Factory
class TasksPresenter(
private val tasksRepository: TasksRepository,
private val view: TasksView
)
TasksViewPresenter
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@Factory
class TasksPresenter(
private val tasksRepository: TasksRepository,
@InjectedParam
private val view: TasksView
)
TasksViewPresenter
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class TasksActivity : TasksView, AppCompatActivity() {
// inject itself as a view
val presenter : TasksPresenter by inject { parametersOf(this) }
}
TasksView
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Tasks Repository
Tasks DataSource Tasks Local DataSource
TasksPresenter
TasksActivity
Tasks Database
TasksViewModel
Koin API
@Factory or @koinViewModel
@Single
@Single
@Single
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Modules
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Gathering definitions into Modules
@Module
class AppModule
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Gathering definitions into Modules
@Module
@ComponentScan("com.my.app")
class AppModule
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import org.koin.ksp.generated.*
startKoin {
modules(
// Class Module
AppModule().module
)
}
Starting with Modules
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import org.koin.ksp.generated.*
startKoin {
modules(
// DSL Module
otherDSLModule,
// Class Module
AppModule().module
)
}
Mix Classes & DSL Modules
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@Module
class DatabaseModule {
@Single
fun taskDao(db : ToDoDatabase) : TaskDao = db.taskDao()
}
Tasks Database
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@Module
class DatabaseModule {
@Single
fun taskDao(db : ToDoDatabase) : TaskDao = db.taskDao()
}
Tasks Database
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Kotlin Compiler Plugin β’
Code Generation
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Fast Compilation Time π
~2 sec - 1000 components
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Easy to Debug π
Generated Koin DSL modules
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DSL and Annotations
Choose what is best for you π
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π https:/
/github.com/InsertKoinIO/
koin-annotations
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Whatβs Next? π
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Koin Downloads Volume π¦ π¦
5M Downloads in 2020
9M Downloads in 2021
πβ¨π
2022: Trends of 5M / Month
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π Roadmap 2022
Structured Release Cycle (~6months)
- Fix Version (bug
fi
xes,
fi
x updates)
- Minor Version (deprecations, minor
featuresβ¦)
- Major Version (hard breaking β¦)
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π Roadmap 2022
Q4 Releases:
Koin 3.3, Koin for Compose
End of Track: Koin 3.1
Q2 Releases:
Koin 3.2, Koin Annotations 1.0
π New DSL, Module includes β¦
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β End of support for Koin 2.X
insert-koin.io/docs/migration/migrate
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// Latest version!
koin_version = "3.1.6"
// Current beta
koin_version = "3.2.0-beta-1"
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Koin β open source
and community driven! π
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@insertkoin_io
insert-koin.io
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But need of real company support
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Long Term Support Releases
& Professional Services
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π kotzilla.io @kotzilla_io
π blog.kotzilla.io
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#goodies π
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Arnaud Giuliani
@arnogiu
Thank you! π