I got an interface `Action` with normal subclass `...

# serialization

[Stylianos Gakis]

I got an interface Action with normal subclass class SomeAction : Action and another interface subclass of type interface ServerAction : Action which itself has implementations like class SpecificServerAction : ServerAction.
I’ve been trying to think of how I need to setup my SerializersModule to make all of this work.
From what I understand since my interface is not sealed, I need to do something like this

polymorphic(Action::class) {
    subclass(ServerAction::class, //??)
    subclass(NavigationPushAction::class, NavigationPushAction.serializer())
    subclass(NavigationPopAction::class, NavigationPopAction.serializer())
    subclass(VoidAction::class, VoidAction.serializer())
}

but how do I do this for the ServerAction? Optimally I’d like to be able to define my ServerAction hierarchy the same way by providing all the subclasses, but I don’t see a way that the dsl allows me to do this?

I could probably do this by creating my own object ServerActionSerializer : KSerializer<ServerAction> { and implementing it, but I’d rather not if possible? I like this subclass approach which can take care of it for me.

Am I missing something, any ideas maybe? Some part of the api I can be using that I am not?

[Emil Kantis]

Are you using the latest version of kotlinx-serialization? I can do polymorphic(Action::class, SpecificServerAction::class, SpecificServerAction.serializer())

[Stylianos Gakis]

That would mean I’d then register a bunch of polymorphic calls if I have many implementations of ServerAction (which I do)
Something like this:

polymorphic(Action::class) {
    subclass(NavigationPushAction::class, NavigationPushAction.serializer())
    subclass(NavigationPopAction::class, NavigationPopAction.serializer())
    subclass(VoidAction::class, VoidAction.serializer())
}
polymorphic(Action::class, SpecificServerAction::class, SpecificServerAction.serializer())
polymorphic(Action::class, Specific2ServerAction::class, Specific2ServerAction.serializer())
polymorphic(Action::class, Specific3ServerAction::class, Specific3ServerAction.serializer())
... and so on

[Stylianos Gakis]

And at no point in this structure am I referencing ServerAction itself. I would’ve expected I’d need to also add something like

polymorphic(ServerAction::class) {
    subclass(SpecificServerAction::class, SpecificServerAction.serializer())
}

And then somehow tell polymorphic(Action::class) about it, since ServerAction is also a subclass of Action.
But that’s not possible I suppose. In my mind that’s what would have made the most sense 😄
Tell Action about all of its subclasses. Tell ServerAction about all of its subclasses as well. And then inform Action that ServerAction is one of them too.

[ephemient]

polymorphic(Action::class) {
    subclass(SpecificServerAction::class, SpecificServerAction.serializer())
}
polymorphic(ServerAction::class) {
    subclass(SpecificServerAction::class, SpecificServerAction.serializer())
}

[Stylianos Gakis]

Aha so I have to duplicate the subclasses since they're technically both implementations of Action and of ServerAction at the same time.
What's with the different syntax between the two, why specify the serializer in one but not the other? Is it just because I can skip it, or is it that I must skip it? If it's just a can, I'd rather keep it consistently the same 😅

[ephemient]

ah, failure to copy-paste. there is a reified helper so you shorten the call arguments, but it's not "must"