What is the best way to deserialize a heterogenous array that looks like this in JSON? I can write a...

# serialization

[Conrad Kramer]

What is the best way to deserialize a heterogenous array that looks like this in JSON? I can write a custom serializer, but I am stuck on which descriptor to use, because listSerialDescriptor assumes a homogenous array.

[{"key": "value"}, "string"]

In Swift, I can pull arbitrary types out of an UnkeyedDecodingContainer in any order I need

[Conrad Kramer]

It seems like the best i can do is use polymorphic serialization for the entire array with a fixed set of subtypes and then runtime cast them, hoping that the object shapes are distinct enough to not be confused for one another

because I cannot use the position in the array as a hint to the serializer even though I know the types ahead of time

[ankushg]

You could also maybe serialize it into JsonElements and write something to manually walk the tree… It’s definitely not ideal, but it lets you do stuff like use the positions in the list in some more manual serialization logic

https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/json.md#json-elements

[Conrad Kramer]

I might have to do that because even Polymorphic does not work here – Polymorphic seems to assume JsonObject and not JsonElement

[Conrad Kramer]

yeah, https://github.com/Kotlin/kotlinx.serialization/blob/920f58979990bace9aaecd300e59b[…]mmonMain/src/kotlinx/serialization/json/internal/Polymorphic.kt

it requires a discriminator, too, so only supports
“internal tagging” in serde.rs parlance

[ephemient]

there is Json.useArrayPolymorphism but that isn't what you want either

[ephemient]

you'll have to write a custom serializer, it doesn't have to be too hard if you use ListSerializer(JsonElement.serializer()) (or equivalents) as a surrogate. It won't work for any format other than JSON, but this kind of structure also doesn't work with other formats so you're not really losing anything

[Conrad Kramer]

Yep, totally. JsonElement ended up working pretty well!