Kotlin序列化:嵌套多态模块

Question

最近，我一直试图为多态类层次结构实现Kotlinx序列化。我使用了这指南，但是我的例子有点复杂。我的班级结构如下：

@Serializable
open class Project(val name: String)

@Serializable
@SerialName("owned")
open class OwnedProject(val owner: String) : Project("kotlin")

@Serializable
@SerialName("owned_owned")
class OwnedOwnedProject(val ownerOwner: String) : OwnedProject("kotlinx.coroutines")

并试图使用以下代码反序列化OwnedOwnedProject实例：

val module = SerializersModule {
    polymorphic(Project::class) {
        polymorphic(OwnedProject::class) {
            subclass(OwnedOwnedProject::class)
        }
    }
}

val format = Json { serializersModule = module }

fun main() {
    val str = "{\"type\":\"owned_owned\",\"name\":\"kotlin\",\"owner\":\"kotlinx.coroutines\",\"ownerOwner\":\"kotlinx.coroutines.launch\"}"
    val obj = format.decodeFromString(PolymorphicSerializer(Project::class), str)
    println(obj)
}

然而，无论我尝试了SerializersModule定义的任何组合，它总是以kotlinx.serialization.json.internal.JsonDecodingException: Polymorphic serializer was not found for class discriminator 'owned_owned'错误告终。

请给我一个提示:如何为给定的类结构(比两个更深)实现SerializersModule？我是不是遗漏了什么？

Answer 1

您似乎也需要直接在OwnedOwnedProject下注册Project，所以序列化程序知道它是一个可能的子类：

val module = SerializersModule {
    polymorphic(Project::class) {
        subclass(OwnedOwnedProject::class)
    }
    polymorphic(OwnedProject::class) {
        subclass(OwnedOwnedProject::class)
    }
}