I'm trying to use generics with polymorphism with ...

# serialization

[Andrew K]

I'm trying to use generics with polymorphism with kotlin serialization. I'm able to get this example code to work: https://github.com/Kotlin/kotlinx.serialization/blob/master/guide/example/example-poly-17.kt. But the third party endpoint I'm trying to deserialize has the type outside of the generic class. I'm not sure how to set that up.

[Andrew K]

Not sure if its the best solution, but this seems to work:

interface MyInterface

@Serializable
data class MyClass(
    val myString: String,
) : MyInterface

@Serializable
data class MyData<T: MyInterface>(
    @SerialName("type") val type: String,
    @SerialName("data") val data: T,
)

val jsonString = "{type: \"myType\", data: {myString: \"myString\"}}"
val json = Json {}
val jsonObject = json.decodeFromString<JsonObject>(jsonString)

val type = jsonObject["type"]?.jsonPrimitive?.content
val myObject = when (type) {
    "myType" -> json.decodeFromString<MyData<MyClass>>(jsonString)
    else -> throw SerializationException("Unknown message type: $type")
}