Any pointers on how to kotlin.serialize with HttpC...

# ktor

[patjackson52]

Any pointers on how to kotlin.serialize with HttpClient to deserialize json with lists as root? I’m using:
HttpClient {
install(JsonFeature) {
serializer = KotlinxSerializer().apply {
setMapper(MyClass::class, MyClass.serializer())
setMapper(AnotherClass::class, AnotherClass.serializer())
}
}
install(ExpectSuccess)
}

Appears I need to setMapper for List<MyClass>, however that is not possible with generics. I see I can get the serializer for it with MyClass.serialzer().list, but registering it to deseriralize/serialize on http requests is not straight forward. Anyone know of a good solution? https://stackoverflow.com/questions/52971069/ktor-serialize-deserialize-json-with-list-as-root-in-multiplatform

[Marcel Kesselring]

Last time I used kotlinx.serialization it wasn't possible to deserialize maps/lists on kotlin/js and I had to wrap every payload. Maybe that is still the case?

[Nikky]

there should be a option to specify the serializer used at the callsite, at least in Fuel there is
i have not used ktor-client for a while

[patjackson52]

Interesting. I’m not targeting JS for this project though.

[Jonas Bark]

right now it's not possible with KotlinxSerializer due to missing generic information. I had the same question - I'll search for the answer

[Nikky]

i had hoped they made use of this in ktor: https://github.com/Kotlin/kotlinx.serialization/blob/master/runtime/jvm/src/main/kotlin/kotlinx/serialization/Resolving.kt#L59

[Nikky]

i think you can make your own kotlinxserializer for ktor using this function, it will work for anything receiving at least since you have a typetoken there

[Jonas Bark]

https://kotlinlang.slack.com/archives/C7A1U5PTM/p1539109136000100

[Nikky]

last time i tried to do that for a outgoing jsonBody the pipeline did not have any typetoken

[Jonas Bark]

@Nikky I think you mean TypeInfo - unfortunately the generic type is erased at runtime (see my link) so that won't help you in this case

[patjackson52]

Right, I don’t think we have type of the generic. I may be able to get something working in my case, but a generic solution doesn’t seem possible currently

[Nikky]

and there is a trick ktor uses to keep it in the pipeline
https://github.com/ktorio/ktor/blob/master/ktor-client/ktor-client-core/ktor-client-core-jvm/src/io/ktor/client/call/TypeInfoJvm.kt

[Nikky]

just not the pipline for sending data apparently

[Nikky]

anyways this TypeInfo and its reified type could be passed to serializerByTypeToken on kotlinx-serialization

[patjackson52]

thanks will take a look

[patjackson52]

I see what you are saying now NikkyAi. I am working with a multiplatform project though, so doesn’t look like serializerByTypeToken is an option.

[Nikky]

well that seems annoying, in that case you can still use a serializer and turn it into a list serializer, you just way have to turn the result into a string and parse it then unless ktor-client has a method for passing in a custom serializer