杰克逊寄存器子类型在科特林不起作用 [英] Jackson registerSubtypes not working in Kotlin

问题描述

我试图在因此，我已将这段代码转换为Kotlin，如下所示:

So I've converted this code into Kotlin like so:

interface Vehicle {
    val name: String
}
class Car @JsonCreator constructor(@JsonProperty("name") override val name: String) : Vehicle
class Truck @JsonCreator constructor(@JsonProperty("name") override val name: String) : Vehicle

class Vehicles @JsonCreator constructor(@JsonProperty("vehicles") var vehicles: List<Vehicle>)

fun main() {
    val MAPPER = jacksonObjectMapper()
    MAPPER.registerSubtypes(NamedType(Truck::class.java, "Truck"))
    MAPPER.registerSubtypes(NamedType(Car::class.java, "Car"))

    val vehicles = Vehicles(listOf(Car("Dodge"), Truck("Scania")))
    val json = MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(vehicles)
    println(json)
}

但是输出结果如下:

{
  "vehicles" : [ {
    "name" : "Dodge"
  }, {
    "name" : "Scania"
  } ]
}

它不包含"@type"字段，因此反序列化不起作用.

It doesn't contain the "@type" field, so deserialization doesn't work.

有什么想法要解决吗?

Jackson Kotlin版本:2.9.6

Jackson Kotlin version: 2.9.6

推荐答案

我已经弄清楚了.

万一将来有人遇到此问题，在此特定示例中，Vehicle类将需要使用@JsonTypeInfo进行注释，如下所示:

In case anyone has this issue in the future, in this particular example the Vehicle class would need to be annotated with @JsonTypeInfo like so :

@JsonTypeInfo(use = NAME, include = PROPERTY)
interface Vehicle

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