kotlinx.serialization is doing some weird name man...

# serialization

[jonathan]

kotlinx.serialization is doing some weird name mangling when stringifying to JSON:
JSON.stringify(UserRegistrationRequest("Jonathan"))
Outputs:

{
  "user_name": "Jonathan",
  "message_name_fojwga$_0": "user_request",
  "SENDER_SIDE_x0f2y$_0": {
    "name$": "CLIENT",
    "ordinal$": 1
  }
}

Where UserRegistrationRequest is:

@Serializable
class UserRegistrationRequest(val user_name: String) : SpyfallMessage {
    override val message_name = Companion.message_name // Overrides from interface SpyfallMessage
    override val SENDER_SIDE = Side.CLIENT  // Overrides from interface SpyfallMessage
    companion object {
        const val message_name = "user_request"
    }
}

[jonathan]

Context: These exist in a Kotlin Multiplatform Common gradle project and act as messages that are sent between the frontend (Multiplatform JS) and backend (Multiplatform Java) via WebSockets using JSON.

[jonathan]

The weird overriding-value (rather than just subclassing an implementation and passing those as constructor parameters) is used because kotlinx.serialization + subclassing doesn't play nicely with JS.

[jonathan]

Finally, they're deserialized to an intermediate class (SpyfallMessageImpl) that's just a tiny data class that accepts message_name and SENDER_SIDE as parameters, which then allows me to further deserialize into the various subclasses manually (it's basically a very long when statement), which means that this name mangling causes deserialization to fail.

[sandwwraith]

Looks just a little bug in a plugin, which passes to the runtime mangled names instead of source names. Afaik, names are mangled when they’re overrides or non-public

[jonathan]

Interesting... is there a way to get around this? Or will I just have to remove the overrides and just re-implement message_name and SENDER_SIDE in every subclass?
That latter workaround doesn't feel in the spirit of OOP...

[sandwwraith]

Try to specify @SerialName on fields. It will also help you to follow code style conventions for field names

[sandwwraith]

By the way, I can’t reproduce your issue. Do you use plugin v0.4 and higher?

[jonathan]

Awesome, thanks - I'll try that and get back to you! I'm using 0.4.1. This particular example is serialized from the JS module.

[sandwwraith]

Ah, I’ve solved the case. Serialization works correctly, but you’ve accidentally imported kotlin.js.JSON instead kotlinx.serialization.json.JSON

[sandwwraith]

The former works incorrectly in your case, because it just dumps runtime JS object representation into string

[jonathan]

Oh whoops! That makes total sense. Thank you so much!