Json.encodeToString() does not include a property of enum type when it has a default value

Default properties of an enum type are not included in JSON payloads when converted using Json.encodeToString()

The following snippet prints {} instead of expected {"status":"OFFLINE"}:

import kotlinx.serialization.Serializable
import kotlinx.serialization.encodeToString
import kotlinx.serialization.json.Json

enum class Status { ONLINE, OFFLINE }

@Serializable
data class User(val status: Status = Status.OFFLINE)

fun main() {
    println(Json.encodeToString(User()))
}

If I remove a default parameter from the User class and create a user passing status, this would print the expected result of {"status":"OFFLINE"}:

@Serializable
data class User(val status: Status)

fun main() {
    println(Json.encodeToString(User(Status.OFFLINE)))
}

Environment

• Kotlin version: 1.5.31
• Library version: 1.3.0
• Kotlin platforms: JVM
• Gradle version: 7.1

[Shpota]

@pdvrieze I understand. I believe it shouldn’t be a default behavior.

[kroegerama]

This seems to work just like expected: https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/basic-serialization.md#defaults-are-not-encoded

You can enable serialization of defaults: https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/json.md#encoding-defaults