kotlinxserialization：如何将具有不同类型对象的JsonArray转换为同一个Class

在正常的序列化发生之前，您可以使用Json transformation来更改您收到的JSON.

本课程:

class EntryPreSerializer : JsonTransformingSerializer<Entry>(Entry.serializer()) {
    override fun transformDeserialize(element: JsonElement): JsonElement {
        return if (element is JsonPrimitive)
            buildJsonObject {
                put("type", JsonPrimitive("StringEntry"))
                put("text", element)
            }
        else element
    }
}

当应用于序列化的Entry对象(我们的多态类)时，它将添加我们在entries中发现JSON原语时进行多态反序列化所需的鉴别器.

为了完成该示例，以下是填充的反序列化的其余部分，包括显示我们如何应用转换:

@Serializable
data class EntryWrapper(val entries: List<@Serializable(with = EntryPreSerializer::class) Entry>)

@Serializable
sealed class Entry

@Serializable
data class StringEntry(val text: String) : Entry()

@Serializable @SerialName("list")
data class ListEntry(val items: List<String>) : Entry()

@Serializable @SerialName("entries")
data class EntriesEntry(val name: String, val entries: List<String>) : Entry()

然后我们可以测试:

fun main() {
    val testJson = """
        {
            "entries": [
                "Simple Text",
                {
                    "type": "list",
                    "items": [
                        "First Item",
                        "Second Item",
                        "Spectral wings appear on your back, giving you a flying speed of 40 feet."
                    ]
                },
                {
                    "type": "entries",
                    "name": "Sub-Entry",
                    "entries": [
                        "New text but could also be the same as above"
                    ]
                }
            ]
        }
    """.trimIndent()
    println(Json.decodeFromString<EntryWrapper>(testJson))
}

它打印:

EntryWrapper(entries=[StringEntry(text=Simple Text), ListEntry(items=[First Item, Second Item, Spectral wings appear on your back, giving you a flying speed of 40 feet.]), EntriesEntry(name=Sub-Entry, entries=[New text but could also be the same as above])])