Getting kotlinx serialization working in multiplatform project - kotlin

Question

I'm taking Kotlin seriazliation for a test drive in a multiplatform project in Kotlin 1.4-M2, following the tutorial on github, but i'm not getting the serialization bit to compile.
This is my build.gradle.kts
plugins {
val kotlinVersion = "1.4-M2"
kotlin("multiplatform") version kotlinVersion
kotlin("plugin.serialization") version kotlinVersion
}
repositories {
mavenCentral()
maven {
url = uri("https://dl.bintray.com/kotlin/kotlin-eap")
}
maven {
url = uri("https://kotlin.bintray.com/kotlinx")
}
jcenter()
gradlePluginPortal()
}
kotlin {
jvm {
compilations.all {
kotlinOptions.jvmTarget = "11"
}
}
js(IR) {
moduleName = "hotel"
browser {
dceTask {
keep(
...
)
}
binaries.executable()
}
}
sourceSets {
// val serializationVersion = "0.20.0-1.4-M2"
val serializationVersion = "0.20.0"
val commonMain by getting {
dependencies {
implementation(kotlin("stdlib-common"))
implementation("org.jetbrains.kotlinx:kotlinx-serialization-runtime-common:$serializationVersion")
}
}
val commonTest by getting {
dependencies {
implementation(kotlin("test-common"))
implementation(kotlin("test-annotations-common"))
}
}
val jvmMain by getting {
dependencies {
implementation(kotlin("stdlib-jdk8"))
implementation(kotlin("reflect"))
implementation("org.jetbrains.kotlinx:kotlinx-serialization-runtime:$serializationVersion")
}
}
val jvmTest by getting {
dependencies {
implementation(kotlin("test-junit"))
}
}
val jsMain by getting {
dependencies {
implementation(kotlin("stdlib-js"))
implementation("org.jetbrains.kotlinx:kotlinx-serialization-runtime-js:$serializationVersion")
}
}
val jsTest by getting {
dependencies {
implementation(kotlin("test-js"))
}
}
all {
languageSettings.enableLanguageFeature("InlineClasses")
}
}
}
I've tried it on a simple data class
#Serializable
data class Test(
val blah: Int = 0
)
import kotlinx.serialization.json.Json <<<--- Unresolved reference: kotlinx
import kotlinx.serialization.json.JsonConfiguration <<<--- Unresolved reference: kotlinx
import kotlin.js.ExperimentalJsExport
import kotlin.js.JsExport
...
fun main() {
val json = Json(JsonConfiguration.Default)
val jstring = json.toJson(Test.serializer(), Test(blah = 3))
println(jstring.toString())
}
It's complaining about Unresolved reference: kotlinx
Is there something specific one needs to do to make kotlinx imports work or should i be using different versions of the serializer libraries?

Answer 1

I got some help on Slack, thanks Sergey!
https://kotlinlang.org/eap/ shows the versions compatible with the EAP
or Milestone releases. You should use the serialization runtime
version 0.20.0-1.4-M2. Note that with this version, you need to add a
single dependency on kotlinx-serialization-runtime in the commonMain
source set, not separate dependencies on
kotlinx-serialization-runtime-common and the platform parts. See the
Specifying dependencies only once section here:
https://blog.jetbrains.com/kotlin/2020/06/kotlin-1-4-m2-released
So in short, my plugin should be matching my Kotlin version
plugins {
val kotlinVersion = "1.4-M2"
kotlin("multiplatform") version kotlinVersion
kotlin("plugin.serialization") version kotlinVersion
}
then under sourceSets, i should be using a single dependency instead of one per platform
sourceSets {
val serializationVersion = "0.20.0-1.4-M2"
val commonMain by getting {
dependencies {
implementation(kotlin("stdlib-common"))
implementation("org.jetbrains.kotlinx:kotlinx-serialization-runtime:$serializationVersion")
}
}
JVM and JS Main should not have any serialization plugin, so those lines should be removed
val jvmMain by getting {
dependencies {
implementation(kotlin("stdlib-jdk8"))
implementation(kotlin("reflect"))
// implementation("org.jetbrains.kotlinx:kotlinx-serialization-runtime:$serializationVersion") <<-- remove this
val jsMain by getting {
dependencies {
implementation(kotlin("stdlib-js"))
// implementation("org.jetbrains.kotlinx:kotlinx-serialization-runtime-js:$serializationVersion") <<-- remove this
}
}