Is it possible to use generics to deserialise / se...

# serialization

[janvladimirmostert]

Is it possible to use generics to deserialise / serialise any type of T that is annotated with @Serializable?

It is possible to make T of type Blah here and it will obviously work, but what type should T be to accept any input

@Serializable
	class Blah1()
	
	inline fun <reified T : Blah1> blah(input: String){
		Json.decodeFromString<T>(input)
	}

Usecase: I want to do something like this and get rid of from / to json boilerplate

fun <REQ, RES> doSomething(input: String, handler: REQ.() -> RES): String {
		val req = Json.decodeFromString<REQ>(input)
		val res = handler.invoke(req)
		return Json.encodeToString<RES>(res)
	}

REQ needs te be deserializable and RES should be serializable

[janvladimirmostert]

this seems to compile

inline fun <reified REQ : Serializable, reified RES : Serializable> doSomething(input: String, handler: REQ.() -> RES): String {
	val req = Json.decodeFromString<REQ>(input)
	val res = handler.invoke(req)
	return Json.encodeToString<RES>(res)
}

let's see if it works ...

[Emil Kantis]

I think you need to use reflection to get the KType of reified T and then there’s a serializerFor(type :KType) or something like it

[Emil Kantis]

You can’t enforce Serializable as type constraint afaik, since it’s an annotation

[janvladimirmostert]

it seems as long as you inline and reify everything, the compiler is happy and everything works

it didn't used to work in the past

this is the working solution

inline fun <reified REQ, reified RES> doSomething(input: String, crossinline handler: (REQ) -> RES): String {
	val req = Json.decodeFromString<REQ>(input)
	val res = handler.invoke(req)
	return Json.encodeToString<RES>(res)
}

[ephemient]

https://github.com/Kotlin/kotlinx.serialization/issues/1348#issuecomment-1472065974

[janvladimirmostert]

nice! then it's just good timing that I tried solving this again today after switching to 1.8.20