Custom Components¶

Dagger Hilt supports defining custom components with @DefineComponent. The installInCustomComponent parameter accepts a reference to such a component class, allowing the generated module to be installed there.

For a general guide on custom Hilt components, see the official Hilt documentation.

Defining a custom component¶

import javax.inject.Scope

@Scope
@Retention(AnnotationRetention.RUNTIME)
annotation class MyCustomScoped

@MyCustomScoped
@DefineComponent(parent = SingletonComponent::class)
interface MyCustomComponent

Explicit component¶

Pass the component class directly with installInCustomComponent:

@AutoBinds(installInCustomComponent = MyCustomComponent::class)
class RepositoryImpl @Inject constructor() : Repository

The processor reads the @Scope-annotated annotation from MyCustomComponent automatically, no need to repeat @MyCustomScoped on the implementation class unless you want the class to be scoped.

Scope auto-detection¶

Place the custom scope annotation on the class and omit installInCustomComponent. The processor finds the @DefineComponent class annotated with that scope automatically:

@MyCustomScoped
@AutoBinds
class RepositoryImpl @Inject constructor() : Repository
// --> @InstallIn(MyCustomComponent::class) generated automatically

Validation rules¶

installIn and installInCustomComponent cannot be used together -> compile error.
A scope annotation on the class that does not match the resolved component -> compile error.
A custom scope annotation with no matching @DefineComponent class -> compile error with a hint to use installInCustomComponent explicitly.
All other features (qualifiers, bindTo, annotation aliases, @AutoBindsIntoSet, @AutoBindsIntoMap, Kotlin object declarations) work with custom components identically to standard Hilt components.