Hello everyone I have a data class ``` import kotl...

# getting-started

[Nikola Milovic]

Hello everyone I have a data class

import kotlinx.serialization.Serializable

@Serializable
data class MessageModel (val senderId : String, val channelId : String, val id : String, val contents : String, val date : Long)

And when I do this inside my (this is a multiplatform project) web app

console.log(message.date::class.simpleName )

The result is Double !! What is happening here? It's causing me runtime errors, as I need a long. This MessageModel I receive from my backend and the value of the date is epoch milis, and the value is 1641905913211 this is interpreted as double. But if I don't use the value of message.date and instead just directly input 1641905913211 it works, meaning the value isn't the issue, but for some reason when serializing it becomes a double? Not sure where to ask this, is this Multiplatform issue, Kotlin general issue?

const val kotlin = "1.6.10"
    const val kotlinxSerialization = "1.3.2"

[ephemient]

https://github.com/Kotlin/kotlinx.serialization/issues/1369 which points to https://youtrack.jetbrains.com/issue/KT-39891 which is supposed to be resolved in Kotlin 1.6.20

[Nikola Milovic]

@ephemient thanks, was looking for the issue

But wait, this is about rounding, while I am getting an incorrect type serialized. Is this the same issue?

[ephemient]

yes, long is being rounded into double representation

[Nikola Milovic]

Oh, that's weird. Can't wait for the fix

[ephemient]

also note that Kotlin/JS uses the JS number type so it doesn't really have a distinction between integer and floating types (it tries, but except for Long, it's a compile time thing only)