Hi all - Working on a CMP app with type-safe nav, ...

# compose

[Dave Leeds]

Hi all - Working on a CMP app with type-safe nav, using 2.9.0-beta03. I noticed when I use a serializable value class, like this...

@Serializable
@JvmInline
value class Id(val value: String)

... as part of a route class like this ...

@Serializable
data class Document(val id: Id)

Then I get an error when trying to navigate with it.

DocumentListScreen(onDocumentClicked = { id -> nav.navigate(Document(id)) })

Here's what the error looks like:

Route Document could not find any NavType for argument id of type Id - typeMap received was {}

I've worked around this by unwrapping the value.

DocumentListScreen(onDocumentClicked = { id -> nav.navigate(Document(id.value)) })

And then reinstantiating the Id value class on the other side. But I'm wondering whether I'm doing things right. Is there a more appropriate way to make this work? I'd love to keep using value classes for things like this if possible.

[Lukáš Kúšik]

have you tried defining and passing in the typeMap?

composable<Screen.Theme>(typeMap) {
   ThemeScreen(navController)
}

private val typeMap = mapOf(
    typeOf<Uuid>() to serializableNavType(Uuid.serializer()),
)

//example with inline fun <reified T> serializableNavType...

although I would have hoped that the value class would get inlined to String and everything would work by default

[Dave Leeds]

Thanks @Lukáš Kúšik - the typeMap is what I needed! Maybe we'll get some automatic support for value classes with this in the future, but this has me squared away for now. And it's much better than the manual wrapping/unwrapping.