docs/reference/koin-core/viewmodel.md
Koin provides multiplatform ViewModel support through the koin-core-viewmodel module. This allows you to declare and inject AndroidX ViewModel instances across all Kotlin Multiplatform targets.
Add the core ViewModel dependency:
// build.gradle.kts (commonMain)
implementation("io.insert-koin:koin-core-viewmodel:$koin_version")
For platform-specific injection APIs, add:
// Android
implementation("io.insert-koin:koin-android:$koin_version")
// Compose Multiplatform
implementation("io.insert-koin:koin-compose-viewmodel:$koin_version")
class UserViewModel(
private val repository: UserRepository
) : ViewModel()
val appModule = module {
viewModel<UserViewModel>()
}
@KoinViewModel
class UserViewModel(
private val repository: UserRepository
) : ViewModel()
val appModule = module {
// With constructor reference
viewModelOf(::UserViewModel)
// With lambda
viewModel { UserViewModel(get()) }
}
Pass parameters at injection time using @InjectedParam:
class DetailViewModel(
@InjectedParam val itemId: String,
private val repository: DetailRepository
) : ViewModel()
val appModule = module {
viewModel<DetailViewModel>()
}
@KoinViewModel
class DetailViewModel(
@InjectedParam val itemId: String,
private val repository: DetailRepository
) : ViewModel()
val appModule = module {
viewModel { params ->
DetailViewModel(
itemId = params.get(),
repository = get()
)
}
}
ViewModels that need their own scoped dependencies use the viewModelScope archetype. Dependencies declared inside viewModelScope are tied to the ViewModel's lifecycle.
val appModule = module {
viewModelScope {
scoped<UserCache>()
scoped<UserRepository>()
viewModel<UserViewModel>()
}
}
@ViewModelScope
class UserCache
@ViewModelScope
class UserRepository(private val cache: UserCache)
@KoinViewModel
@ViewModelScope
class UserViewModel(
private val repository: UserRepository
) : ViewModel()
val appModule = module {
viewModelScope {
scoped { UserCache() }
scoped { UserRepository(get()) }
viewModel { UserViewModel(get()) }
}
}
:::info
Dependencies inside viewModelScope are created when the ViewModel is first accessed and destroyed when the ViewModel is cleared.
:::
Use koinViewModel() in Composable functions:
@Composable
fun UserScreen() {
val viewModel = koinViewModel<UserViewModel>()
// or with parameters
val detailVM = koinViewModel<DetailViewModel> { parametersOf("item_123") }
}
Use by viewModel() delegate in Activity or Fragment:
class UserActivity : AppCompatActivity() {
private val viewModel: UserViewModel by viewModel()
// With parameters
private val detailVM: DetailViewModel by viewModel { parametersOf("item_123") }
}
Add SavedStateHandle to your ViewModel constructor - Koin injects it automatically:
@KoinViewModel
class MyViewModel(
private val handle: SavedStateHandle,
private val repository: UserRepository
) : ViewModel() {
val userId: String? = handle["userId"]
}
val appModule = module {
viewModel<MyViewModel>() // Compiler Plugin DSL
// or
viewModelOf(::MyViewModel) // Classic DSL
}
| Approach | Module Declaration | Scope Declaration |
|---|---|---|
| Compiler Plugin DSL | viewModel<MyVM>() | viewModelScope { viewModel<MyVM>() } |
| Annotations | @KoinViewModel | @KoinViewModel @ViewModelScope |
| Classic DSL | viewModelOf(::MyVM) | viewModelScope { viewModelOf(::MyVM) } |
| Platform | Injection API |
|---|---|
| Compose | koinViewModel<MyVM>() |
| Android | by viewModel() |