Anyone else seeing errors like this after upgrading to Kotlin 1.3.20? The class it’s trying to generate a serializer for has a custom serializer defined within it (code is at https://github.com/charleskorn/batect/blob/master/app/src/main/kotlin/batect/os/Command.kt)

This prints `{"bar":"lorem"}`:

@Serializable
	data class Foo(@Transient val bar: String)
	
	println(Json.stringify(Foo.serializer(), Foo("lorem")))

Do I miss anything about

@Transient

?

Hi people, I'm really not getting serialization to work in my multi-platform kotlin-native project. I'm just getting "unresolved reference: serializer" and gradle refuses to compile. Is this even supported or am I just doing something wrong? Example code available at: https://github.com/rundfunk47/MultiPlatformSerialization

Maybe a bit of a stupid question, but being from a Swift background: Can anyone help me to get this code using a generic argument

T

instead of

Data

?

fun deserialize(string: String): Data {
        return Json.nonstrict.parse(Data.serializer(), string)
    }

I'd like to introduce a new extension to KotlinX Serialization: Mirror! https://github.com/lightningkite/mirror-kotlin It's an independent plugin for KotlinX Serialization that also adds some reflective functionality. Polymorphism works for all platforms, and annotations have been entirely replaced with a manifest file. The plugin can also read directly from your common dependencies, allowing you to easily serialize things from your libraries as well.

Hi guys. I have a question. I’m working on a multiplatform project with a common module sharing code between Android/iOS. In the common module, I have some model classes annotated with @Serialization. With Android, everything works as is expected, but when I try to generate the library for iOS I get this error:

> Task :common:compileKotlinIos
error: compilation failed: Can’t locate polymorphic serializer definition

(gradle 4.10.3, kotlin 1.3.20, kotlinx-serialization-runtime-native 0.9.1) There is some workaround or suggestion to fix this issue?

When working with custom serializers, do you really need to provide separate ones for the type itself and for the collection of this type? ex:

@Serializable(with = FooSerializer::class)
 val names: List<Foo>

Works only if I define

FooSerializer: KSerializer<List<Foo>>

. I'm wondering if I can define only

FooSerializer: KSerializer<Foo>

and let the kotlin to deal with collections.

To clarify, the performance of : 1.

@ContextualSerialization

on a file 2.

@Serializable(with =)

on a field 3.

Json.install()

is the same? It's 3 different ways of runtime resolution?

Hello, I’ve applied the plugin, added dependencies in an MPP and annotated any class I send with @Serializable. I’ve got a response in the format of Response<SomeModel> to parse in kotlin js (node). The error I get is the following:

TypeError: tmp$.serializer is not a function at compiledSerializer (<http://localhost:9000/bundle.js:44171:87>) at serializer (<http://localhost:9000/bundle.js:36889:22>) at KotlinxSerializer.lookupSerializerByType_0 (<http://localhost:9000/bundle.js:54654:64>) at Coroutine$read_ro165m$.doResume (<http://localhost:9000/bundle.js:54591:40>) at KotlinxSerializer.read_ro165m$ (<http://localhost:9000/bundle.js:54621:21>) at Coroutine$JsonFeature$Feature$install$lambda_0.doResume (<http://localhost:9000/bundle.js:54456:63>) at <http://localhost:9000/bundle.js:54488:21> at SuspendFunctionGun.loop_0 (<http://localhost:9000/bundle.js:62922:16>) at <http://localhost:9000/bundle.js:62879:31> at SuspendFunctionGun.proceed (<http://localhost:9000/bundle.js:62887:49>)
message: "tmp$.serializer is not a function"

Any idea? -> Seems like the problem comes from generics? I’ve just tried sending a simple model as response and this worked. So what’s the deal with generics?

probably not, but it's fairly trivial to write your own. Most of those types produce a canonical representation via

toString()

and have a static parser of that representation

make sure you also set

encodeDefaults = false

in

Json

constructor call

I want to serialize a set of IP addresses. I have created an InetAddressSerializer, but how do I apply it to a set using annotations? I can't use

(..).set

in an annotiation.

@Serializable
data class SessionState(
        @Serializable(with = InstantSerializer::class)
        val start: Instant,
        val ips: Set<InetAddress>?
)

How do I do Json.stringfy on a data class?

I have

@Serializable
class Response(
        val localDate: LocalDate
)

@Serializable(with = LocalDateSerializer::class)
expect class LocalDate

@Serializer(LocalDate::class)
expect object LocalDateSerializer : KSerializer<LocalDate>

But it complains that no Serializer for element of type LocalDate has been found. Am I doing something wrong ?

Hi there. I'm not following this thread too close, just checking time to time for some features that were blocking me in the past. I've just read the project status at github and failed to find a ticket in youtrack. What is the status of polymorphic collections issue? I need to send a list of abstract items to a client and call some virtual code for each of them.

Hey, I got this error only in iOS project:

error: compilation failed: Can't locate polymorphic serializer definition

Hello, is it possible to serialize objects e.g.

sealed class Error {
    @Serializable
    data class Fatal(val message: String) : Error()

    @Serializable
    object Unauthorized: Error()

    @Serializable
    object Forbidden: Error()
}

It does not throw an error but it is not the same object if i deserialize it multiple times.

Specifically the

serialize

and

deserialize

functions. Note that you do need to write your own descriptor that further defines the fields for

type

and

data

.

I have a working MPP using ktor with serialization & models in a shared module. Builds and runs on Android, however building to iOS I get some build errors around serialization. Specifically: An operation is not implemented: Serializable classes with inheritance Is there a list of deltas between what is implemented on the different platforms and the status of different features on each platform?

What is the plan regarding improving error handling? E.g. when sending a JSON request to a ktor server all it can do is respond with an error message like

Strict JSON encountered unknown key: title\nYou can disable strict mode to skip unknown keys

. That's not very helpful for the developer implementing the API client because they don't know the full JSON path and/or location where the problem has occurred. Also it communicates implementation-specific information in the message which you don't want to report to clients. More useful would be something like

Unexpected property 'title' in 'request.posts[0].author' at offset 123

.

Decoding invalid enum values is quite weird 😄

IllegalStateException: -3 is not among valid MyEnum choices, choices size is 7

Another question: Is it possible to single-step through the generated serializers? Or check out code and variables when going up the stacktrace?

Is there a way to completely prevent the serializer from ever serializing a

null

value anywhere?

Try this, @ribesg: https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/custom_serializers.md

I need to deserialize the results of a search query to Algolia. The result object contains a

hits

array containing the results of the query. Depending on the index the query was run on, the model of these results change. How do I implement that with

kotlinx.serialization

? - Can I use generics? - Can I use inheritance, with one subclass per model? - Can I say that these results should stay “raw”, like JsonObject or String, and deserialize them later to the correct model?

Does an util/option exist to add backslashes to Json.stringify result?

Are there any plans to add a streaming reader/writer for JSON? Just like JsonReader/JsonWriter in Gson/Moshi? I'm currently using Moshi (only JsonReader/JsonWriter classes) but am looking for a multiplatform solution for Kotlin/Native.

Is there anything I would gain by migrating from moshi/gson to kotlin serialization besides multi platform?

Is it possible to deserialize JSON into its basic untyped structure of just Maps, Lists, and primitives?