Hello! I want to use a third-party API that expects either int or string as a value for id. Like: ...

# serialization

[madhead]

Hello!

I want to use a third-party API that expects either int or string as a value for id. Like:

Request {
    id: int | string,
    name: string,
    // other fields
}

How do I do that with kotlinx.serialization? I only need to serialize my classes to JSON, no deserialization.

[spand]

Tried setting the id type to Any and just store a String or Int in it?

[madhead]

No, because:

1. I want more type-safety
2. Serializer has not been found for type ‘Any’. To use context serializer as fallback, explicitly annotate type or property with @ContextualSerialization

[madhead]

I’m thinking about a sealed class, like Either + custom serializer

[spand]

Ok. Last guess I will bother you with. Does the api actually distinguish between int and string ? Or will it simply accept both… ie. is id=42 equivalent to id=“42”

[madhead]

I don’t know, but I guess yes. String ids are like usernames: @user

[Edward Taylor]

I would go for a sealed class and a JsonParametricSerializer: https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/json_transformations.md#json-parametric-polymorphic-deserialization

[madhead]

Thank you, Edward! That’s it!