Are there plans to support suspending `serialize`/`deserialize`? I need to make a database/cache call within deserialize to determine which

DeserializationStrategy

should be used depending on a field value.

👋 Hello, team! I am wandering where can we find more reference for how a

format de/encoder

[Link] works with a

serializer

[Link]. I am following the Kotlin Serialization Guide, and I can see this

encodeSerializableValue()

method is how de/encoder interact with serializer, but wandering if I can find more detail instructions or example guide. Thank you.

encoder.encodeSerializableValue(serializer, value)

On Kotlin/Native (iOS) I’m getting an unsupported call of refied inlined function when using

Json.encodeToString(value: T)

. This is the following code snippet.

override var market: Market?
        get() = marketJson?.let(json::decodeFromString)
        set(value) { marketJson = value?.let(json::encodeToString) }

Is this a potential bug in K/N or serialization? Using Kotlin 1.6.10, serialization 1.3.1. Full stack trace in thread.

I'm trying to map enum to int values:

@Serializable
enum class ItemType {
    @SerialName("0") Zero,
    @SerialName("1") First,
}

But it fails with the following exception:

JsonDecodingException: Unexpected JSON token at offset 194: Expected quotation mark '"', but had '1' instead
    JSON input: ....."type":1,.....

It doesn't seem to work because

SerialName

is expecting a string and json has an int. I can think of two ways to solve this: 1. Enabling lenient mode - I don't like this solution as it also removes restrictions from other fields, which I prefer to keep 2. Implementing a custom serializer - seems like too much of boilerplate code for such a simple task Am I missing something?

Hi, is there a way to write generic serializers for JVM classes that do nothing but use

toString()

? Currently, I'm writing code like

@Serializer(File::class)
object FileSerializer : KSerializer<File> {
    override fun serialize(encoder: Encoder, value: File) = encoder.encodeString(value.toString())
    override fun deserialize(decoder: Decoder) = File(decoder.decodeString())
}

@Serializer(URI::class)
object URISerializer : KSerializer<URI> {
    override fun serialize(encoder: Encoder, value: URI) = encoder.encodeString(value.toString())
    override fun deserialize(decoder: Decoder) = URI(decoder.decodeString())
}

but this duplication seems rather dumb. Can I somehow generalize these serializers into one, and use that single serializer for both

File

and

URI

?

hi, I want to serialize a custom class into a nested map (with my own encoder, not introducing JSON into my code base). For example, if I have my data classes defined like this:

@Serializable
data class Project(val name:String, val owners: List<Users>)

@Serializable
data class Users(val name: String)

After serialization, I wish to get a nested map equals to:

val map = mutableMapOf<String, Any>()
map.put("name", "project_name")
map.put("owners", listOf(mapOf("name" to "user1"), mapOf("name" to "user2"))

Could you please give me some hint how can I implement this

Encoder

please ( I do have a

Decoder

working BTW)? Should my Encoder extend the

AbstractEncoder()

or

TaggedEncoder()

? May I get some document for how to implement this? The official guide only contains an example for serializing to

List

, but does not show how to get the key values if I want to serialize to

Map

. Thank you very much.

Hi, quick question, I have and endpoint that has a dynamic property, it could be a

String

, an

Integer

or a

Boolean

, is there a way to achieve that behaviour with serialization?

Beware of the default behavior on default values! It can lead to very unexpected results…

@Serializable
    data class Event(
        val id: String,
        val date: Date = Date.now(),
    )

    @Test
    fun test() {
        repeat(100) {
            println(Json.encodeToString(Event("Test")))
        }
    }

…
{"id":"Test"}
{"id":"Test"}
{"id":"Test","date":"2022-05-18T10:00:47.011Z"}
{"id":"Test"}
{"id":"Test"}
{"id":"Test"}
…

Hello everybody 🙂 I wished ask somebody to help me investigate a bug in compile time related to serialization. This bug break my builds already half a year, fortunately the project in the report is a pet-project and I am able to wait a fix, but it is a little bit long-play issue and I wished to ask help here 🙂 thank you

How would I write a custom serializer for json input that looks like this

[ { "somekey": { } }, { "someotherkey": { } } ]

I wanna be able to check the name of the first key in the object and then serialize to a specific class depending on what it is

This message was deleted.

Is it possible to deserialize an array into an object? For example, turning something like

["Bob", 24]

into

class Person(val name: String, val age: Int)

. Assuming of course that I already know the array corresponds to the

Person

class (in reality, my data looks more like

{ "person": ["Bob", 24] }

Why doesn't that work you literally can see that I have kotlinx serialization, ktor client and content negotiations:

I'm trying to deserialize a CBOR message that I'm getting over FFI (Project Panama), but I keep getting a

kotlinx.serialization.cbor.internal.CborDecodingException: Expected start of string, but found 50

error. The byte array data seems to be the same as the original one in Rust when converting them to a hexadecimal format. I can deserialize normally the same data on Rust through the

cbor4ii

library. I also tried using another library (

cborium

) and I still get the same error in the Kotlin side.

Hi i need to call SOAP api. There is no official library so i am using https://github.com/pdvrieze/xmlutil . Is there a way how to specify more namespaces than one, using this library? My soap request is like this. I need to create a data classes to represent it.

<?xml version="1.0" encoding="utf-8"?>
<soapenv:Envelope xmlns:soapenv="<http://schemas.xmlsoap.org/soap/envelope/>" xmlns="<http://www.pds.eu/vOKO/v0200>" xmlns:eph="<http://www.ccv.cz/EPH_GCP01G>">
   <soapenv:Body>
      <Request vOKOid="EPH_GCP01G">
         <RequestContent>
            <eph:REQUEST>
               <eph:GETDATA>1</eph:GETDATA>
               <eph:IDLAST>22</eph:IDLAST>
            </eph:REQUEST>
         </RequestContent>
      </Request>
   </soapenv:Body>
</soapenv:Envelope>

As you can see, there are more than one namespace in the envelope.I xmlutil is only @XmlSerialName which can specify only one namespace. How should i handle this?

I have defined the following classes :

interface DeviceAttribute<T> {
    val name: String
    val value: T
}

@SharedImmutable
internal val module = SerializersModule {
    polymorphic(baseClass = DeviceAttribute::class, baseSerializer = null) {
        subclass(AlarmEntryDevice::class)
        default { Unknown.serializer() }
    }
}

@Serializable
data class Device(
    val id: String,
    val name: String,
    val icon: String,
    val iconOptions: List<String>,
    val attributes: List<DeviceAttribute<*>> = emptyList(),
    val profiles: List<ActiveProfileMode>?,
)

But I get this error

Serializer has not been found for type 'Any?'. To use context serializer as fallback, explicitly annotate type or property with @Contextual

Adding the annotation doesn’t change anything though. What should I do?

Is it possible to tell a

SerializersModule

to look for an attribute called

name

instead of

type

without registering a custom serializer?

My system persists the following object graph as JSON serialized with kotlinx.serialization:

@Serializable
data class Category(val id: String, val children: Set<Category> = emptySet())

For the sake of having “stable” diff of the updated JSON file, I’d like to enforce order of the

children

Set’s elements based on lexicographic order of the element’s

id

field. The solution I was able to come up with is to use custom serializer based on `JsonTransformingSerializer`:

object CategorySetSerializer : JsonTransformingSerializer<Set<Category>>(SetSerializer(Category.serializer())) {
    override fun transformSerialize(element: JsonElement) = super.transformSerialize(
        if (element is JsonArray)
            JsonArray(element.sortedBy { it.jsonObject["id"]?.jsonPrimitive?.content })
        else
            element
    )
}

@Serializable
data class Category(
    val id: String,

    @Serializable(with = CategorySetSerializer::class)
    val children: Set<Category> = emptySet()
)

Unfortunately, this solution seems too low level, brittle and JSON specific. What can be other approaches to enforce particular ordering of serialized Set’s elements? Ideally, I’d like to pass in the

@Serializable

my custom comparator when specific Set’s elements ordering is required.

Hi, Is there an easy way to mutate a

JsonObject

? If I have such an object already and I wish to add a couple of elements somewhere nested deep inside is that possible programatically? I think I would have to effectively clone the whole thing myself in order to achieve that.

will Kotlin serialization plugin be able to capture annotations applied on setters or getters?

@SerialInfo
@Target{
AnnotationTarget.PROPERTY_SETTER,
AnnotationTarget.PROPERTY_GETTER}
annotation class KDocumentId

data class File( @get: KDocumentId val name:String?= null)
// this will just return empty list []
descriptor.getElementAnnotations(elementIndex)

Hi, is it possible to override serializer? I have a library class annotated as

@Serializable

but I would like to use different serializer than default one but I can't change the library code.

I made this serializer for my json structure

companion object Serializer : JsonContentPolymorphicSerializer<Renderer>(Renderer::class) {
    override fun selectDeserializer(element: JsonElement) = when {
        "slimVideoMetadataSectionRenderer" in element.jsonObject -> SlimVideoMetadataSectionRenderer.serializer()
        "itemSectionRenderer" in element.jsonObject -> RelatedItemsRenderer.serializer()
        "shelfRenderer" in element.jsonObject -> ShelfRenderer.serializer()
        else -> throw NoWhenBranchMatchedException()
    }
}

though how would I make it serialize using the object inside of the key?

I’m getting this error message

Polymorphic serializer was not found for class discriminator 'batteryPercentage', JSON input: {"name":"batteryPercentage","value":70}

@JsonClassDiscriminator("name")
interface DeviceAttribute

@Serializable
data class Device(
    val id: String,
    val name: String,
    val icon: String,
    val iconOptions: List<String>,
    val attributes: List<DeviceAttribute> = emptyList(),
    val profiles: List<ActiveProfileMode>?,
)

@Serializable
@SerialName("batteryPercentage")
data class BatteryPercentage(val value: Int) : DeviceAttribute

What am I missing here?

Why does that throw an exception? (thread)

How do I use sealed interfaces for union types properly? (thread)

I have a json file I am parsing with ktx.serialization which has a

$schema

key at the top level. I am parsing it into a

Map<String, Def>

(Def is a class I have defined), so when the string value in the

$schema

key is encountered, it throws an exception. I simply want to ignore the value of the

$scheam

key, what is the best way to do this?

I need some help with deserialization. I get an

IndexOutOfBoundsException

and I do not really get why. (thread)

I can define a serializer for a class in many places. On the class with

@Serializable

, on the field, for a whole file, in multiple ways with a SerializersModules, and there's also reflection. Is the order of priority defined somewhere? I'm asking because I want to see how to override a serializer that's defined on a class with

@Serializable(with = ...)

, and it's not clear in which order serializers are considered and selected.

After updating from com.android.tools.build:7.0.4 to com.android.tools.build:7.2.1, the application began to crash when calling the <reified T> StringFormat.encodeToString(value: T): String method. The bug manifests itself only in the release version, where there is: minifyEnabled true, shrinkResources true Has anyone come across a similar situation and have a solution?

Hey all! At some point, we started running into this issue: https://github.com/Kotlin/kotlinx.serialization/issues/1940 It’s not impacting our

main

branch, but we have a branch where we’ve made a couple structural changes (with absolutely no new

@Serializable

classes) and things are just breaking for mysterious reasons 😞 Has anyone else here experienced it? Any ways to narrow down the cause?