interface Animal

@Serializable
class Dog : Animal

@Serializable
class Cat : Animal

// subclasses are explicitly registered in serializerModule.

client.get<...>("...") {
    contentType(Json)
    body = Dog()
}

How do I get ktor to do polymorphic serialisation correctly?

body

ends up being

{}

instead of

{ "type": "Dog" }

.

I think you need sealed classes for that

I do have

@Serializable

, was just impatient when writing the code lol.

But not sealed classes. Last I checked polymorphism was only supported on sealed hierarchies

It's supported everywhere now. Unless you're talking about ktor.

No, I was talking about serialisation itself. Good to know then and I'm out of my depth here 😀

Haha, thanks for trying though. Looks like a bug in ktor.

moko-network support allOf,anyOf,oneOf and it implemented with generation of special serializers, like this - https://github.com/icerockdev/moko-network/blob/master/network/src/commonTest/kotlin/OneOfTest.kt#L122