CODEWITHSUNDEEP
kotlinjacksondeserializationkotlin-delegate
Hugo Caupert
Hugo Caupert

Reputation: 21

Kotlin delegated property deserialization with Jackson

I am trying to deserialize a data class the built from a delegated property.
Here is a quick snippet to reproduce my case :

@JsonTypeInfo(use = JsonTypeInfo.Id.DEDUCTION, defaultImpl = BaseResponseDto::class)
interface ResponseDto {
    val name: String
    val age: Int
}

data class BaseResponseDto(
    override val name: String,
    override val age: Int,
) : ResponseDto

data class ExtendedResponseDto(
    private val base: ResponseDto,
    val city: String,
) : ResponseDto by base

val json = """{
    "name": "Thomas",
    "age": 3,
    "city": "Paris"
}"""

val mapper = jacksonObjectMapper()
val dto = mapper.readValue<ExtendedResponseDto>(json)

This code throws this exception.

Exception in thread "main" com.fasterxml.jackson.module.kotlin.MissingKotlinParameterException: Instantiation of [simple type, class xxx.ExtendedResponseDto] value failed for JSON property base due to missing (therefore NULL) value for creator parameter base which is a non-nullable type

I've been trying to play with @JsonUnwrapped and other annotations but could not make it work. Having and sub-class that only have the delegate as constructor parameter seems to be working, but does not meet my needs...

// This can be deserialized
data class ExtendedResponseDto(
    private val base: ResponseDto,
) : ResponseDto by base

I hope I am missing something and there is an easy solution. Final objective is not to duplicate the base interface fields

Thank's alot for you help !

Upvotes: 2

Views: 225

Answers (0)

Related Questions