How do I make this polymorphically serializable? ...

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[andylamax]

How do I make this polymorphically serializable?

@Serializable
sealed class Result<out T> {
    @Serializable
    class Success<out T>(val data: T) : Result<T>()

    @Serializable
    class Failure<out T>(val msg: String) : Result<T>()

    companion object {
        private fun <T> resultContext(serializer: KSerializer<T>) = SerializersModule {
            polymorphic<Result<T>> {
                subclass(Success.serializer(serializer))
                subclass(Failure.serializer(serializer))
            }
        }

        fun <T> stringify(serializer: KSerializer<T>, res: Result<T>): String {
            return Json(context = resultContext(serializer)).stringify(
                Result.serializer(serializer),
                res
            )
        }

        fun <T> parse(serializer: KSerializer<T>, json: String): Result<T> {
            return Json(context = resultContext(serializer)).parse(
                Result.serializer(serializer),
                json
            )
        }
    }
}}

So that If I have a class

@Serializable
data class Person(val name:String)

I can call

Result.stringify(Result.Serializer(Person.serializer()),Result.Success(Person("Andy))) // This says class Person is not registered for polymorphic serialization

I have little knowledge in Polymorphic Serialization.
Also, I need to be able to serialize a Result.Success<Person?>(null) . Currently I don't know how to do so. Help?

[kursivee]

I’m not familiar with it either but it seems that you need to modify your stringily function like so (change the Result.serializer(serializer))

fun <T> stringify(serializer: KSerializer<T>, res: Result<T>): String {
    return Json(context = resultContext(serializer)).stringify(
            PolymorphicSerializer(Result::class),
            res
    )
}

but then parse doesn’t work and not sure how to get that working.
should be the same for parse just have to cast it

[andylamax]

I tried that already, I get the same error. Person is not registered for serialization

[kursivee]

oh sorry also change your call to stringify to

Result.stringify(Person.serializer(), Result.Success(Person("Andy")))

[kursivee]

this is what i’m using

@Serializable
sealed class Result<out T> {
    @Serializable
    class Success<out T>(val data: T) : Result<T>()
    @Serializable
    class Failure<out T>(val msg: String) : Result<T>()
    companion object {
        private fun <T> resultContext(serializer: KSerializer<T>) = SerializersModule {
            polymorphic<Result<T>> {
                subclass(Success.serializer(serializer))
                subclass(Failure.serializer(serializer))
            }
        }
        fun <T> stringify(serializer: KSerializer<T>, res: Result<T>): String {
            return Json(context = resultContext(serializer)).stringify(
                    PolymorphicSerializer(Result::class),
                    res
            )
        }
        fun <T> parse(serializer: KSerializer<T>, json: String): Result<T> {
            return Json(context = resultContext(serializer)).parse(
                    PolymorphicSerializer(Result::class),
                    json
            ) as Result<T>
        }
    }
}

@Serializable
data class Person(val name: String?)

fun main(args: Array<String>) {
    val jsonData = Result.stringify(Person.serializer(), Result.Success(Person("hey")))
    println(jsonData)

    when(val data = Result.parse(Person.serializer(), jsonData)) {
        is Result.Success -> println(data.data)
        is Result.Failure -> println(data.msg)
    }
}

[andylamax]

I find out that, I am still getting the same error, but If I add

polymorphic<Any> {
  subclass(serializer)
}

in the SerializersModule Then the error goes away. But again, I can't serialize Result.Success<Person?>(null)