Kotlinx.serialization: kotlin Multiplatform module: build errors

[daberni]

I tried using kotlinx.serialization in a kotlin multiplatform project in a commons module with some small model classes looking like the following:

@Serializable
open class Document {
    var _id: String? = null
    var _rev: String? = null
}

@Serializable
class User : Document() {

    var username: String = ""
    var email: String = ""
    var rollen: List<UserRoles> = emptyList()

    companion object {
        val TYPE = "User"
    }
}

But when building via command-line I get following errors:

Unresolved reference: kotlinx
Cannot access 'Serializable': it is internal in 'kotlin.io'
This class does not have a constructor

Its mentioned in the description that it should work with the kotlinx-serialization-runtime-common dependency which I am using. The plugin should stay the same as far as I read.

I am using kotlin 1.2.21, but already tried 1.2.20, 1.2.10 with the same results.
Gradle 4.4.1

[sandwwraith]

Seems just library dependency was not recognized in buildscript. Can you check it for errors and post it here?

[daberni]

The dependency tree by gradle is the following:

+--- org.jetbrains.kotlin:kotlin-stdlib-common:1.2.21
\--- org.jetbrains.kotlinx:kotlinx-serialization-runtime-common:0.4
     \--- org.jetbrains.kotlin:kotlin-stdlib-common:1.2.10 -> 1.2.21

IntelliJ shows them as known but gradlew throws those errors..
However in the tests of the jvm-target kotlinx isn't known . Only when adding an additional dependency to kotlinx-serialization-runtime there. It looks like the common dependency isn't grabbed correctly.

I setup a minimal testproject here: https://github.com/daberni/kotlinx.serialization_test

Another issue which came up is, that Mapper isn't recognizing @Optional correctly. Parsing JSON works successfully, but working with a map where the key is missing doesn't work.

[sandwwraith]

Yes, this is how multiplatform build works for now: you should specify both dependency on common part of the library in your common module and dependency on platform part of the library in your platform module – just as same as deps on kotlin-stdlib and kotlin-stdlib-common

Current Mapper implementation assumes that it can just request all properties from the map. It likely will be changed in future.

[daberni]

Thank you so far for the update.

When I specify the additional dependency in the jvm target and run the tests from the referenced project I get the following runtime exceptions:

kotlinx.serialization.SerializationException: Can't locate companion serializer for class class SomeDataClass (Kotlin reflection is not available)

    at kotlinx.serialization.SerializationKt.serializer(Serialization.kt:25)
    at SampleTest.otherTest(SampleTest.kt:54)

I am not sure if the exception is a bit misleading as I assumed that reflection isn't required and Serializers are generated at compile time by the plugin or am I still missing something?

Steps are reproducible in the given repo.

[sandwwraith]

You need to apply plugin: 'kotlinx-serialization' in platform buildscript too

[daberni]

Thanks for the help 👍

It would be nice if the documentation could explain these steps in more detail. Probably I will make a PR for this 😉

[sandwwraith]

You're welcome! Any help would be appreciated :)

[sandwwraith]

I suppose I can close this now.

[hlung]

You need to apply plugin: 'kotlinx-serialization' in platform buildscript too

@sandwwraith Do you mean to add that to the build.gradle at the project root folder?

[sandwwraith]

@hlung No. but for every apply plugin: 'kotlin' or 'kotlin-platform-xxx' or 'kotlin-multiplatform'.

[jeremyrempel]

If anyone else runs into this issue make sure have enableFeaturePreview('GRADLE_METADATA') in settings.gradle

[matthiaswelz]

I received the same error message ("Cannot access 'Serializable': it is internal in 'kotlin.io'"), but only because I forgot the import kotlinx.serialization.*. IntelliJ did not suggest to add this import automatically, so I first assumed some configuration issue. Maybe it helps someone arrivin here via Google.

[MajidHJ]

I get rid of that error by import java.io.Serializable. I hope it helps.

[avanlex]

I received the same error message ("Cannot access 'Serializable': it is internal in 'kotlin.io'"), but only because I forgot the import kotlinx.serialization.*. IntelliJ did not suggest to add this import automatically, so I first assumed some configuration issue. Maybe it helps someone arrivin here via Google.

I think it's better way to add import kotlinx.serialization.Serializable instead importing all content of kotlinx.serialization
at least it works for me

[fisiodes]

I receive Cannot access 'Serializable': it is internal in 'kotlin.io too. If i try to add apply plugin: 'kotlinx-serialization i receive:Plugin with id 'kotlinx-serialization' not found. solved by migrating gradle to kotlin dsl and thanks to @matthiaswelz

I received the same error message ("Cannot access 'Serializable': it is internal in 'kotlin.io'"), but only because I forgot the import kotlinx.serialization.*. IntelliJ did not suggest to add this import automatically, so I first assumed some configuration issue. Maybe it helps someone arrivin here via Google.

[sandwwraith]

@fisiodes Try to add import kotlinx.serialization.* to your file

[fisiodes]

@sandwwraith yes thanks i already solved the problem with that import and migrating gradle to kotlin dsl as i wrote above. Without migrating to kotlin dsl plugin was not found