Generate exportable external interfaces for encodeToDynamic/decodeFromDynamic

What is your use-case and why do you need this feature? We use kotlinx.serialization to map json strings from our API response into Kotlin data classes.

We also use kotlinx.serialization to

• map our Kotlin data classes into standard JS objects using encodeToDynamic for JS consumers of our KMP library and
• JS Objects back to data classes using decodeFromDynamic when JS consumers pass in data

This is great because it allows us to reuse our existing serialization logic for network requests, while exposing data in a shape that JS consumers expect.

It’s much faster than manually declaring external interfaces for each data class and writing mapping methods.

However, these methods only return/consume dynamic. This means that we don’t get Typescript definitions like we would with a standard external interface in the new JS IR Backend.

Ideally, we would be able to have external interfaces generated based on our SerialDescriptors, and be able to export them for use in our JS clients so they know what to expect.

Describe the solution you’d like

• Serializer walks through the SerialDescriptors for each option
• Serializer generates external interface representations of what it’s spitting out
  • acceptable if there are reasonable limitations on what can be converted to an external interface
• allows users to mark external interface with @JsExport to get type definitions
• encodeToDynamic can be cast to that generated external interface

[aSemy]

@ankushg Hi, I’ve written a prototype library that will generate TypeScript interfaces based on @Serializable classes.

https://github.com/adamko-dev/kotlinx-serialization-typescript-generator

@Serializable
class MyClass(
  val aString: String,
  var anInt: Int,
  val aDouble: Double,
  val bool: Boolean,
  private val privateMember: String,
)

fun main() {
  val tsGenerator = KxsTsGenerator()
  println(tsGenerator.generate(MyClass.serializer()))
}

Generated TypeScript interface:

export interface MyClass {
  aString: string;
  anInt: number;
  aDouble: number;
  bool: boolean;
  privateMember: string;
}

Is this useful for you? It’s not finished, but if you have any thoughts, please let me know.

[sandwwraith]

@aSemy Looks great!

I assume ticket can be closed now, as I said, this is a bit out of scope of the core library