I have the following data class in my common code: ```data class SomeModel(val createdAt: Instant)`...

# multiplatform

[Johann Pardanaud]

I have the following data class in my common code:

data class SomeModel(val createdAt: Instant)

In JS and Darwin targets, do you any recommandation to provide native dates for the createdAt property?

Details in thread ➡️ 🧵

[Johann Pardanaud]

I was thinking about extension properties/functions:

// JS
@JsExport fun SomeModel.createdAtJS() = createdAt.toJSDate()

// Darwin
val SomeModel.createdAtNS get() = createdAt.toNSDate()

However :

• The JS target doesn’t support extension properties, and the extension function is a bit deceptive being a simple function with the receiver passed as a parameter: createdAtJS(myModel)
• The model still accepts an Instant type in its constructor, thus I can’t instantiate it from the JS/Darwin targets since I can’t provide an instance of this type. I could create functions to make the conversion tho.
• The original createdAt property is still available and can be read from all targets.
How do you solve this in your own codebase?

[simon.vergauwen]

Why not use KotlinX Datetime? It covers Instant.

https://github.com/Kotlin/kotlinx-datetime

[Johann Pardanaud]

Actually, I use KotlinX DateTime! Sorry, I did not precise it 😅

[Johann Pardanaud]

However, Instant from this lib is not JS exportable

[Johann Pardanaud]

but at least it provides those nice extension functions toJSDate() and toNSDate()

[Johann Pardanaud]

I’m juste wondering how to use them properly in my codebase

[simon.vergauwen]

Right, I would create smart-constructors for them. Afaik top-level non-extension functions are the best for that if you want to call them from everywhere.

[Johann Pardanaud]

For the constructor, maybe on my property, instead of using Instant, I could use String to accept ISO8601 strings, that way all the targets can instantiate the data class

[Johann Pardanaud]

Yeah, you’re probably right 🙂