[Solved] Hi I’ve encountered an issue with nested root components. Seems to be

unregister

is not being called when navigated back from inner router The error occurs when 1. I navigate to inner router component A. 2. Navigate back 3. and again navigate to router component A Root Router -> Inner Router -> Child -> NavBack -> Navigate forward

Could you suggest an example of such a factory?

hello, i am running into the same error when updating from

decompose

0.3.1 to a newer version (i tried with 0.5.1, 0.5.0 and 0.4.0). the code does compile (i only had to update the imports for the

router

package) but i do get an error during runtime.

what i do:

i have 3

Configurations

with 3

Childs

. some

Childs

use the same components, so i thought it would be nice, if the components would only be created once, so that their state is shared between `Configurations`/`Childs`.

how i implemented it (works with

decompose

0.3.1):

so instead of creating a component in the

createChild()

function (which is provided as

childFactory

) and using its

ComponentContext

, i created variables in the root component (like the one for the

routerState

) and used the

ComponentContext.childContext()

function.

class RootComponent internal constructor(
    componentContext: ComponentContext,
    private val hue: (ComponentContext, (Hue.Output) -> Unit) -> Hue,
    private val homematicIP: (ComponentContext, (HomematicIP.Output) -> Unit) -> HomematicIP
) : Root, ComponentContext by componentContext {

    constructor(
        ...
    )

    override val hueComponent: Hue
// the following line fails
        get() = hue(childContext("hueComponent"), this::onHueOutput) 

    override val homematicIPComponent: HomematicIP
        get() = homematicIP(childContext("homematicIPComponent"), this::onHomematicIPOutput)

    private val router =
        router<Configuration, Root.Child>(
            initialConfiguration = Configuration.Dashboard,
            handleBackButton = true,
            childFactory = ::createChild
        )

    override val routerState: Value<RouterState<*, Root.Child>> = router.state

    private fun createChild(configuration: Configuration, componentContext: ComponentContext): Root.Child =
        when (configuration) {
            is Configuration.Dashboard -> Root.Child.Dashboard(hueComponent, homematicIPComponent)
            is Configuration.Hue -> Root.Child.Hue(hueComponent)
            is Configuration.HomematicIP -> Root.Child.HomematicIP(homematicIPComponent)
        }

    ...
}

interface Root {
    val hueComponent: Hue
    val homematicIPComponent: HomematicIP
    val routerState: Value<RouterState<*, Child>>

    sealed class Child {
        data class Dashboard(
            val hueComponent: com.trashcoder.trashboard.common.philips_hue.integration.Hue,
            val homematicIPComponent: com.trashcoder.trashboard.common.homematic_ip.integration.HomematicIP) : Child()
        data class Hue(
            val hueComponent: com.trashcoder.trashboard.common.philips_hue.integration.Hue) : Child()
        data class HomematicIP(
            val homematicIPComponent: com.trashcoder.trashboard.common.homematic_ip.integration.HomematicIP) : Child()
    }

    ...
}

Exception in thread "main" java.lang.IllegalStateException: Check failed.
	at com.arkivanov.essenty.statekeeper.DefaultStateKeeperDispatcher.register(DefaultStateKeeperDispatcher.kt:42)
	at com.arkivanov.decompose.statekeeper.ChildStateKeeperKt.child(ChildStateKeeper.kt:11)
	at com.arkivanov.decompose.ComponentContextExtKt.childContext(ComponentContextExt.kt:21)
	at com.arkivanov.decompose.ComponentContextExtKt.childContext$default(ComponentContextExt.kt:18)
	at com.trashcoder.trashboard.common.root.integration.RootComponent.getHueComponent(RootComponent.kt:50)

@trashcoder You are creating multiple instances of the same child components with the same keys. E.g. your

hueComponent

getter calls

childContext("hueComponent")

every time when it is called. The second attempt of creating child context with the same key will fail. One of the possible fixes is to use

lazy

instead:

override val hueComponent: Hue by lazy { hue(childContext("hueComponent"), this::onHueOutput) }

Or maybe you can just assign the value (depends on your needs)

override val hueComponent: Hue = hue(childContext("hueComponent"), this::onHueOutput)

Wow. That was fast. I will try it tomorrow. Thanks a lot! 🙏🏻