Hello, World! I have a sealed class `Event` and am...

# serialization

[bod]

Hello, World! I have a sealed class Event and am using @JsonClassDiscriminator successfully for its subtypes. But now I have one of the subtypes (Message) that should itself be a sealed class with a few sub-subtypes:

┌─────┐
        │Event│  discriminator: "type"
        └──▲──┘
┌─────┐    │   ┌───────┐
│React├────┴───┤Message│  discriminator: "subtype"
└─────┘        └───▲───┘
          ┌───┐    │    ┌────┐
          │Add├────┴────┤Edit│
          └───┘         └────┘

Naturally I'd put another @JsonClassDiscriminator on Message but that's not allowed.

Any tip on how I should handle this?

[Dominaezzz]

Why is it not allowed?

[bod]

I'm not sure what the reason is, but the doc says:

It is not possible to define different class discriminators for different parts of class hierarchy.

and if you actually try it in the IDE it will be red 🙂

[Dominaezzz]

What happens if you ignore the IDE and run the code?

[bod]

haven't tried to be honest...

[bod]

but the documentation seems pretty clear about it

[Dominaezzz]

Indeed. You might need to make Message a concrete class then, then have a polymorphic member.

[bod]

I did something similar currently, but it's not very satisfactory - I'd love to have a class hierarchy that looks like the API one

[Dominaezzz]

Though thinking about it, I suppose it'd be rather tricky to serialize something like this.

val event: Event = Add()

Since there isn't a way to figure out the Message class in between.

[Dominaezzz]

You could consider using a single discriminator for the whole hierarchy.

[bod]

You could consider using a single discriminator for the whole hierarchy.

Do you mean a change in the backend? (it's out of my hands, this is actually for the Slack API)

[Dominaezzz]

I see. At this point your best best is to create an issue and/or custom serializer.

[bod]

I saw a bunch of issues about the topic but not sure they were exactly like what I'm trying to do 🙂 I think I'll open one then. Thanks a lot for replying!