Kotlin 密封接口序列化答案

【问题标题】：Kotlin sealed interface serializationKotlin 密封接口序列化
【发布时间】：2021-10-19 15:18:03
【问题描述】：

Kotlin 密封接口序列化似乎被破坏了，除非使用显式注册的序列化模块。我错过了什么吗？

import kotlinx.serialization.*
import kotlinx.serialization.json.Json
import kotlin.test.Test

sealed interface iFoo {
    @Serializable
    @SerialName("a")
    class A() : iFoo//Foo(),
}

class EventTest {
    @Test
    fun testKotlinLang() {
//        // this works
//        val json = Json { serializersModule = SerializersModule {
//                polymorphic(iFoo::class) {
//                    subclass(iFoo.A::class, iFoo.A.serializer())
//                } } }

        val json = Json

        val a = iFoo.A() as iFoo
        val s = json.encodeToString(a)
        val a1: iFoo = json.decodeFromString(s)
    }
}

Class 'A' is not registered for polymorphic serialization in the scope of 'iFoo'.
Mark the base class as 'sealed' or register the serializer explicitly.
kotlinx.serialization.SerializationException: Class 'A' is not registered for polymorphic serialization in the scope of 'iFoo'.
Mark the base class as 'sealed' or register the serializer explicitly.
    at kotlinx.serialization.internal.AbstractPolymorphicSerializerKt.throwSubtypeNotRegistered(AbstractPolymorphicSerializer.kt:102)
    at kotlinx.serialization.internal.AbstractPolymorphicSerializerKt.throwSubtypeNotRegistered(AbstractPolymorphicSerializer.kt:113)
    at kotlinx.serialization.PolymorphicSerializerKt.findPolymorphicSerializer(PolymorphicSerializer.kt:109)
    at kotlinx.serialization.json.internal.StreamingJsonEncoder.encodeSerializableValue(StreamingJsonEncoder.kt:224)
    at kotlinx.serialization.json.Json.encodeToString(Json.kt:85)
    at io.almer.EventTest.testKotlinLang(EventTest.kt:64)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at 
..............

注意我使用的是多平台模式但是JVM运行失败。

【问题讨论】：

标签： json kotlin serialization kotlin-multiplatform

【解决方案1】：

显然它还没有实现:(

https://github.com/Kotlin/kotlinx.serialization/issues/1417

【讨论】：

【解决方案2】：

使用sealed interface 和@JvmInline 的可能解决方法：https://github.com/Kotlin/kotlinx.serialization/issues/1417#issuecomment-844300565

【讨论】：