Parse a nested JSON with Kotlinx.Serialization - json

Question

I've been playing with Kotlinx.serialization, and I have been trying to parse a substring:
Given a JSON like:
{
"Parent" : {
"SpaceShip":"Tardis",
"Mark":40
}
}
And my code is something like:
data class SomeClass(
#SerialName("SpaceShip") ship:String,
#SerialName("Mark") mark:Int)
Obviously, Json.nonstrict.parse(SomeClass.serializer(), rawString) will fail because the pair "SpaceShip" and "Mark" are not in the root of the JSON.
How do I make the serializer refer to a subtree of the JSON?
P.S: Would you recommend retrofit instead (because it's older, and maybe more mature)?

Answer 1

#Serializable
data class Parent(
#SerialName("Parent")
val someClass: SomeClass
)
#Serializable
data class SomeClass(
#SerialName("SpaceShip")
val ship: String,
#SerialName("Mark")
val mark: Int
)
fun getSomeClass(inputStream: InputStream): SomeClass {
val json = Json(JsonConfiguration.Stable)
val jsonString = Scanner(inputStream).useDelimiter("\\A").next()
val parent = json.parse(Parent.serializer(), jsonString)
return parent.someClass
}

Answer 2

import kotlinx.serialization.*
import kotlinx.serialization.json.Json
#Serializable
data class Parent(
#SerialName("Parent")
val parent: SomeClass
)
#Serializable
data class SomeClass(
#SerialName("SpaceShip")
val ship:String,
#SerialName("Mark")
val mark:Int
)
fun main() {
val parent = Json.parse(Parent.serializer(), "{\"Parent\":{\"SpaceShip\":\"Tardis\",\"Mark\":40}}")
println(parent)
}