I'm having hard time trying to make a generic dese...

# javascript

[Michal Klimczak]

I'm having hard time trying to make a generic deserializing work.

private suspend inline fun <reified T> fetch(
    url: String,
    state: ObservableValue<Collection<T>>
) {
    val response1 = client.get(url).body<List<T>>(typeInfo<List<T>>())
    val response2 : List<T> = client.get(url).body()
    val type = typeOf<T>()
}

neither response1, nor response2 is able to properly derive the generic type, even though it's reified.
TypeInfo(type=class List, reifiedType=[object Object], kotlinType=null)

And calling typeOf fails with a weird " This marker function should never been called. Looks like compiler did not eliminate it properly. Please, report an issue if you caught this exception."

When the type is provided directly, everything works fine, obviously (kotlinType is properly defined). Is that not possible at all, even with reified type? Can I create a KType for List<T>?
Kotlin 1.6.10

[Anton Lakotka [JB]]

Can you share more details? Like a full code snippet that fails.

[Michal Klimczak]

The snippet I have here uses ktor client and some backend urls so that would be hard, but I guess the same thing should fail with just kotlinx serialisation. I'll prepare sth like that.

[Michal Klimczak]

OK, so pure kotlinx serialization works fine

fun test() {
    val projects = listOf(Project(1, "A"), Project(2, "B"))
    val encodedProjects = Json.encodeToString(projects)
    val decodedProjects : List<Project> = deserializeGeneric(encodedProjects)
    println(decodedProjects)
}

private inline fun <reified T> deserializeGeneric(encodedStuff: String) =
    Json.decodeFromString<T>(encodedStuff)

But similar ktor doesn't

fetch<List<Project>>()

private inline fun <reified T> fetch() {
    val client = HttpClient(Js) {
        install(ContentNegotiation) { json(Json { ignoreUnknownKeys = true }) }
    }

    AppScope.launch {
        val response: T = client.get("$baseUrl/admin/project").body()
        println(response)
    }
}

JsonDecodingException
Expected class JsonObject as the serialized body of kotlinx.serialization.Polymorphic<List>, but had class JsonArray

[Michal Klimczak]

should I search around ktor rather than kotlin js then?

[Anton Lakotka [JB]]

should I search around ktor rather than kotlin js then?

I guess so. But I’ll try to reproduce anyway.

[Michal Klimczak]

then I'll wait for your results before reposting on ktor. thank you!

[Anton Lakotka [JB]]

Ok I got time.
And verified the basic setup JVM Server + JS Client. It seems working well for me.
Can you check? https://github.com/antohaby/kotlin-jvm-js-sample
Open in IDEA. then run JVM Server by running main function.
• And then run gradle task: ./gradlew jsNodeRun