hello :wave: any idea why `kotlinx-serialization` ...

# serialization

[Dariusz Kuc]

hello 👋
any idea why kotlinx-serialization wraps some json elements in " making them strings?, i.e. given generic KSerializer

object AnyKSerializer : KSerializer<Any> {
    override val descriptor: SerialDescriptor = buildClassSerialDescriptor("Any")
   ...
    override fun deserialize(decoder: Decoder): Any {
        val jsonDecoder = decoder as JsonDecoder
        val element = jsonDecoder.decodeJsonElement() // why primitives are always strings?

        return deserializeJsonElement(element)
    }

    private fun deserializeJsonElement(element: JsonElement): Any = when (element) {
        is JsonObject -> {
            element.mapValues { deserializeJsonElement(it.value) }
        }
        is JsonArray -> {
            element.map { deserializeJsonElement(it) }
        }
        is JsonPrimitive -> element.content
    }
}

and a simple data class

@Serializable
data class AnyMap(
    val data: Map<String, @Serializable(with = AnyKSerializer::class) Any>
)

trying to deserialize

{
  "data": {
    "intVal": 123
  }
}

but jsonDecoder.decodeJsonElement() converts 123 int to "123" string

any ideas?

[russhwolf]

When you call element.content it will always return a String. You can call toInt() or toDouble() (or the nullable variants) to get one of those types instead, but you won’t know statically whether you can do that safely if your type is Any.

[Dariusz Kuc]

hmm indeed element is a String guess part of the confusion was the kdoc that is says it is a given element without quotes

/**
 * Content of given element without quotes. For [JsonNull] this methods returns `null`
 */
public abstract val content: String

[Dariusz Kuc]

thanks

[Dariusz Kuc]

to add to this -> we can check element.isString() whether we should be converting the underlying content string or not