kotlinx.serialization
kotlinx.serialization copied to clipboard
Published
20 hours ago •
Kotlin
Kotlin
Generic custom serializer breaks kotlin-kapt compilation
Describe the bug
When using a generic custom serializer (see example below), adding the kotlin-kapt plugin with something that uses kapt (like data binding or Dagger) causes a Kotlin compiler error.
To Reproduce
The following generic custom serializer works as expected in an Android project when kotlin-kapt is not in use:
data class Wrapped<T>(
val value: T
)
open class WrappedSerializer<T>(private val serializer: KSerializer<T>): KSerializer<Wrapped<T>> {
override val descriptor: SerialDescriptor = serializer.descriptor
override fun deserialize(decoder: Decoder): Wrapped<T> =
Wrapped(serializer.deserialize(decoder))
override fun serialize(encoder: Encoder, obj: Wrapped<T>) =
serializer.serialize(encoder, obj.value)
}
@Serializable
data class A(
@Serializable(with = WrappedSerializer::class)
val value: Wrapped<String>
)
However, adding
apply plugin: 'kotlin-kapt'
and
android {
dataBinding {
enabled = true
}
}
causes building the build to fail with the following compiler exception:
error: incompatible types: Class<WrappedSerializer> cannot be converted to Class<? extends KSerializer<?>> @kotlinx.serialization.Serializable(with = com.alexvanyo.kotlintest.WrappedSerializer.class)
Expected behavior
Applying the kotlin-kapt plugin shouldn't cause a compiler error.
As a temporary workaround, specifying the type does allow compilation with kotlin-kapt, but this isn't ideal as it requires a separate class for every serialized type:
class StringWrappedSerializer(serializer: KSerializer<String>): WrappedSerializer<String>(serializer)
@Serializable
data class A(
@Serializable(with = StringWrappedSerializer::class)
val value: Wrapped<String>
)
Environment
- Kotlin version: 1.3.61
- Library version: 0.14.0
- Kotlin platform: JVM
- Gradle version: 5.4.1
- IDE version: Android Studio 3.5.3
Just confirmed this still occurs with Kotlin 1.3.71 and a runtime version of 0.20.0. I can also upload a test project if that would be helpful!
Worked around this by moving all network code into a separate module with no kapt plugin.
Did some more investigation, and I believe this is the same issue as https://youtrack.jetbrains.com/issue/KT-30346, so that would make this firmly a kapt bug.
In https://github.com/JetBrains/kotlin, there's two commits that reference the issue, https://github.com/JetBrains/kotlin/commit/66754e62dadd5ad05921b630ab3d4b2b58a33a83, and https://github.com/JetBrains/kotlin/commit/a0778ad703d7d7ce3cb4532d5954fa32a6045db3, that latter of which reverts the first.
Not sure what the relevant priority is, but I'm going to link this issue on https://youtrack.jetbrains.com/issue/KT-30346.
I am getting an issue similar to this. I am using databinding and kotlinx.serialization. I have an attribute with different names, so I included the @JsonNames annotation with more that one name.
@Serializable
data class DocMessage(
val id: Int = 0,
@JsonNames("type1", "type2")
val type: Type
)
@Serializable(with =TypeSerializer::class)
enum class Type(val value: String) {
PDF("pdfDoc"), IMAGE("imageDoc"), UNKNOWN("unknown");
}
@Serializer(forClass = Type::class)
class TypeSerializer {
override val descriptor: SerialDescriptor
get() = PrimitiveSerialDescriptor("Type", PrimitiveKind.STRING)
override fun deserialize(decoder: Decoder): Type {
val value = decoder.decodeString()
return values().find { it.value == value } ?: UNKNOWN
}
override fun serialize(encoder: Encoder, value: Type) {
encoder.encodeString(value.value)
}
}
But when I tried to build the project, the console printed the following error:
org.jetbrains.kotlin.backend.common.BackendException: Backend Internal error: Exception during file facade code generation
File being compiled: file:///Users/user/AndroidStudioProjects/MyApplication/app/src/main/java/com/example/myapplication/DocMessage.kt
The root cause java.lang.IllegalArgumentException was thrown at: org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.addSyntheticAnnotationsToDescriptor(SerializerCodegenImpl.kt:123)
at org.jetbrains.kotlin.backend.common.CodegenUtil.reportBackendException(CodegenUtil.kt:239)
at org.jetbrains.kotlin.codegen.PackageCodegenImpl.generate(PackageCodegenImpl.java:78)
at org.jetbrains.kotlin.codegen.DefaultCodegenFactory.generatePackage(CodegenFactory.kt:77)
at org.jetbrains.kotlin.codegen.DefaultCodegenFactory.generateModule(CodegenFactory.kt:62)
at org.jetbrains.kotlin.codegen.KotlinCodegenFacade.compileCorrectFiles(KotlinCodegenFacade.java:35)
at org.jetbrains.kotlin.kapt3.AbstractKapt3Extension.contextForStubGeneration(Kapt3Extension.kt:278)
at org.jetbrains.kotlin.kapt3.AbstractKapt3Extension.analysisCompleted(Kapt3Extension.kt:171)
at org.jetbrains.kotlin.kapt3.ClasspathBasedKapt3Extension.analysisCompleted(Kapt3Extension.kt:102)
at org.jetbrains.kotlin.cli.jvm.compiler.TopDownAnalyzerFacadeForJVM.analyzeFilesWithJavaIntegration$invokeExtensionsOnAnalysisComplete(TopDownAnalyzerFacadeForJVM.kt:112)
at org.jetbrains.kotlin.cli.jvm.compiler.TopDownAnalyzerFacadeForJVM.analyzeFilesWithJavaIntegration(TopDownAnalyzerFacadeForJVM.kt:122)
at org.jetbrains.kotlin.cli.jvm.compiler.TopDownAnalyzerFacadeForJVM.analyzeFilesWithJavaIntegration$default(TopDownAnalyzerFacadeForJVM.kt:86)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler$analyze$1.invoke(KotlinToJVMBytecodeCompiler.kt:252)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler$analyze$1.invoke(KotlinToJVMBytecodeCompiler.kt:243)
at org.jetbrains.kotlin.cli.common.messages.AnalyzerWithCompilerReport.analyzeAndReport(AnalyzerWithCompilerReport.kt:113)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.analyze(KotlinToJVMBytecodeCompiler.kt:243)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli(KotlinToJVMBytecodeCompiler.kt:90)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli$default(KotlinToJVMBytecodeCompiler.kt:56)
at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:169)
at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:52)
at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:92)
at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:44)
at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:98)
at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:412)
at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:112)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileIncrementally(IncrementalCompilerRunner.kt:358)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileIncrementally$default(IncrementalCompilerRunner.kt:300)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileImpl$rebuild(IncrementalCompilerRunner.kt:119)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileImpl(IncrementalCompilerRunner.kt:170)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compile(IncrementalCompilerRunner.kt:81)
at org.jetbrains.kotlin.daemon.CompileServiceImplBase.execIncrementalCompiler(CompileServiceImpl.kt:607)
at org.jetbrains.kotlin.daemon.CompileServiceImplBase.access$execIncrementalCompiler(CompileServiceImpl.kt:96)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:1658)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at java.rmi/sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:359)
at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:200)
at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.rmi/sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at java.rmi/sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:562)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:796)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:677)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:676)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.IllegalArgumentException: Can't use arguments with defaults for serializable annotations yet
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.addSyntheticAnnotationsToDescriptor(SerializerCodegenImpl.kt:123)
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.addElementsContentToDescriptor(SerializerCodegenImpl.kt:116)
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.generateSerialDescriptor(SerializerCodegenImpl.kt:77)
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.generateSerialDesc(SerializerCodegenImpl.kt:145)
at org.jetbrains.kotlinx.serialization.compiler.backend.common.SerializerCodegen.generate(SerializerCodegen.kt:36)
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl$Companion.generateSerializerExtensions(SerializerCodegenImpl.kt:46)
at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationCodegenExtension.generateClassSyntheticParts(SerializationCodegenExtension.kt:30)
at org.jetbrains.kotlin.codegen.ImplementationBodyCodegen.generateSyntheticPartsAfterBody(ImplementationBodyCodegen.java:448)
at org.jetbrains.kotlin.codegen.MemberCodegen.generate(MemberCodegen.java:135)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:305)
at org.jetbrains.kotlin.codegen.MemberCodegen.genSyntheticClassOrObject(MemberCodegen.java:319)
at org.jetbrains.kotlin.codegen.ClassBodyCodegen.generateBody(ClassBodyCodegen.java:113)
at org.jetbrains.kotlin.codegen.MemberCodegen.generate(MemberCodegen.java:132)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:305)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:289)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:315)
at org.jetbrains.kotlin.codegen.ClassBodyCodegen.generateDeclaration(ClassBodyCodegen.java:176)
at org.jetbrains.kotlin.codegen.ClassBodyCodegen.generateBody(ClassBodyCodegen.java:80)
at org.jetbrains.kotlin.codegen.MemberCodegen.generate(MemberCodegen.java:132)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:305)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:289)
at org.jetbrains.kotlin.codegen.PackageCodegenImpl.generateClassesAndObjectsInFile(PackageCodegenImpl.java:119)
at org.jetbrains.kotlin.codegen.PackageCodegenImpl.generateFile(PackageCodegenImpl.java:138)
at org.jetbrains.kotlin.codegen.PackageCodegenImpl.generate(PackageCodegenImpl.java:70)
... 47 more
This didn't happen when I disabled the databinding. To solve this, I changed the implementation of my DocMessage class
@Serializable
data class DocMessage(
val id: Int = 0,
@SerialName("type1")
@JsonNames("type2")
val type: Type
)
or
@Serializable
data class DocMessage(
val id: Int = 0,
val type1: Type? = null,
val type2: Type? = null
)
But none of the solutions solves the original problem completely. @JsonNames cannot be used with more than one value and requires to be used with the @SerialName to work.
I have the same issue as @eugenio1590 describes.
I have the following enum with a JsonNames attribute with two values:
@Serializable
enum class ReportStatus(val order: Int) {
@SerialName("E")
ERROR(-1),
@SerialName("O")
OPEN(0),
@SerialName("D")
@JsonNames("A", "N") // Decode the A and N values as FINAL.
FINAL(2),
}
This causes the build to fail:
org.jetbrains.kotlin.backend.common.BackendException: Backend Internal error: Exception during file facade code generation
File being compiled: file:///Users/some-user/Projects/some-project/app/src/main/java/com/somepackage/model/ReportStatus.kt
The root cause java.lang.IllegalArgumentException was thrown at: org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.addSyntheticAnnotationsToDescriptor(SerializerCodegenImpl.kt:123)
at org.jetbrains.kotlin.backend.common.CodegenUtil.reportBackendException(CodegenUtil.kt:239)
at org.jetbrains.kotlin.codegen.PackageCodegenImpl.generate(PackageCodegenImpl.java:78)
at org.jetbrains.kotlin.codegen.DefaultCodegenFactory.generatePackage(CodegenFactory.kt:77)
at org.jetbrains.kotlin.codegen.DefaultCodegenFactory.generateModule(CodegenFactory.kt:62)
at org.jetbrains.kotlin.codegen.KotlinCodegenFacade.compileCorrectFiles(KotlinCodegenFacade.java:35)
at org.jetbrains.kotlin.kapt3.AbstractKapt3Extension.contextForStubGeneration(Kapt3Extension.kt:278)
at org.jetbrains.kotlin.kapt3.AbstractKapt3Extension.analysisCompleted(Kapt3Extension.kt:171)
at org.jetbrains.kotlin.kapt3.ClasspathBasedKapt3Extension.analysisCompleted(Kapt3Extension.kt:102)
at org.jetbrains.kotlin.cli.jvm.compiler.TopDownAnalyzerFacadeForJVM.analyzeFilesWithJavaIntegration$invokeExtensionsOnAnalysisComplete(TopDownAnalyzerFacadeForJVM.kt:112)
at org.jetbrains.kotlin.cli.jvm.compiler.TopDownAnalyzerFacadeForJVM.analyzeFilesWithJavaIntegration(TopDownAnalyzerFacadeForJVM.kt:122)
at org.jetbrains.kotlin.cli.jvm.compiler.TopDownAnalyzerFacadeForJVM.analyzeFilesWithJavaIntegration$default(TopDownAnalyzerFacadeForJVM.kt:86)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler$analyze$1.invoke(KotlinToJVMBytecodeCompiler.kt:252)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler$analyze$1.invoke(KotlinToJVMBytecodeCompiler.kt:243)
at org.jetbrains.kotlin.cli.common.messages.AnalyzerWithCompilerReport.analyzeAndReport(AnalyzerWithCompilerReport.kt:113)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.analyze(KotlinToJVMBytecodeCompiler.kt:243)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli(KotlinToJVMBytecodeCompiler.kt:90)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli$default(KotlinToJVMBytecodeCompiler.kt:56)
at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:169)
at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:52)
at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:92)
at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:44)
at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:98)
at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:412)
at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:112)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileIncrementally(IncrementalCompilerRunner.kt:358)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileIncrementally$default(IncrementalCompilerRunner.kt:300)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileImpl(IncrementalCompilerRunner.kt:160)
at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compile(IncrementalCompilerRunner.kt:81)
at org.jetbrains.kotlin.daemon.CompileServiceImplBase.execIncrementalCompiler(CompileServiceImpl.kt:607)
at org.jetbrains.kotlin.daemon.CompileServiceImplBase.access$execIncrementalCompiler(CompileServiceImpl.kt:96)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:1658)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at java.rmi/sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:359)
at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:200)
at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.rmi/sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at java.rmi/sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:562)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:796)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:677)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:676)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.IllegalArgumentException: Can't use arguments with defaults for serializable annotations yet
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.addSyntheticAnnotationsToDescriptor(SerializerCodegenImpl.kt:123)
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerForEnumsCodegen.addElementsContentToDescriptor(SerializerForEnumsCodegen.kt:64)
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.generateSerialDescriptor(SerializerCodegenImpl.kt:77)
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl.generateSerialDesc(SerializerCodegenImpl.kt:145)
at org.jetbrains.kotlinx.serialization.compiler.backend.common.SerializerCodegen.generate(SerializerCodegen.kt:36)
at org.jetbrains.kotlinx.serialization.compiler.backend.jvm.SerializerCodegenImpl$Companion.generateSerializerExtensions(SerializerCodegenImpl.kt:46)
at org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationCodegenExtension.generateClassSyntheticParts(SerializationCodegenExtension.kt:30)
at org.jetbrains.kotlin.codegen.ImplementationBodyCodegen.generateSyntheticPartsAfterBody(ImplementationBodyCodegen.java:448)
at org.jetbrains.kotlin.codegen.MemberCodegen.generate(MemberCodegen.java:135)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:305)
at org.jetbrains.kotlin.codegen.MemberCodegen.genSyntheticClassOrObject(MemberCodegen.java:319)
at org.jetbrains.kotlin.codegen.ClassBodyCodegen.generateBody(ClassBodyCodegen.java:113)
at org.jetbrains.kotlin.codegen.MemberCodegen.generate(MemberCodegen.java:132)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:305)
at org.jetbrains.kotlin.codegen.MemberCodegen.genClassOrObject(MemberCodegen.java:289)
at org.jetbrains.kotlin.codegen.PackageCodegenImpl.generateClassesAndObjectsInFile(PackageCodegenImpl.java:119)
at org.jetbrains.kotlin.codegen.PackageCodegenImpl.generateFile(PackageCodegenImpl.java:138)
at org.jetbrains.kotlin.codegen.PackageCodegenImpl.generate(PackageCodegenImpl.java:70)
... 46 more
If i remove the second value of JsonNames, the build succeeds:
@SerialName("D")
@JsonNames("A", "N") // Decode the A and N values as FINAL.
FINAL(2),
Any updates on the feature above?
Like @steurt , I'm trying to use @JsonNames with an enum values, but I'm getting the same exception with kapt with kotlinx-serialization-json:1.3.2.
Thank you for considering supporting this! 🙏
Can confirm we've hit the same roadblock with multiple @JsonNames values as well. @sandwwraith @shanshin is there any update WRT this issue?
We also encountered the same problem while using kapt (for dagger) together with serialization in a same module:
@Serializable
data class A(val p1: Int, val p2: Float)
@Serializable
data class B(
@JsonNames("id1", "id2") // this is ok, compile passed.
val id: String,
@JsonNames("result1", "result2") // compile error!
val result: List<A>,
)
Seems there is kind of a workaround for this problem (using generic serializer, and not creating a typed version of it for each type parameter).
I declared parameterized typealias, with the value class being annotated with Serializable that refers to the generic serializer class, which accepts the generic parameter.
typealias SafeList<T> = @Serializable(with = SafeListSerializer::class) KindListWrapper<T>
where the implementations are as follows:
KindListWrapper implementation
class KindListWrapper<T : Any>(private val list: List<T>) : List<T> by list {
override fun equals(other: Any?): Boolean {
if (this === other) return true
if (javaClass != other?.javaClass) return false
other as KindListWrapper<*>
if (list != other.list) return false
return true
}
override fun hashCode(): Int {
return list.hashCode()
}
override fun toString(): String {
return list.toString()
}
}
SafeListSerializer implementation
@OptIn(ExperimentalSerializationApi::class)
@Serializer(forClass = KindListWrapper::class)
class SafeListSerializer<T : Any>(
private val valueSerializer: KSerializer<T>,
) : KSerializer<KindListWrapper<T>> {
private var throwableHandler: ((Throwable) -> Unit)? = null
constructor(elementSerializer: KSerializer<T>, throwableHandler: ((Throwable) -> Unit)?) : this(
elementSerializer
) {
this.throwableHandler = throwableHandler
}
private val listSerializer = ListSerializer(valueSerializer)
override val descriptor: SerialDescriptor = listSerializer.descriptor
override fun deserialize(decoder: Decoder): KindListWrapper<T> {
val values = mutableListOf<T?>()
val compositeDecoder = decoder.beginStructure(descriptor)
while (true) {
val index = compositeDecoder.decodeElementIndex(descriptor)
if (index == CompositeDecoder.DECODE_DONE) break
values.add(readElement(compositeDecoder))
}
compositeDecoder.endStructure(descriptor)
return KindListWrapper(values.filterNotNull())
}
override fun serialize(encoder: Encoder, value: KindListWrapper<T>) {
listSerializer.serialize(encoder, value)
}
private fun readElement(compositeDecoder: CompositeDecoder): T? {
return try {
val jsonDecoder = compositeDecoder as JsonDecoder
val jsonElement = jsonDecoder.decodeJsonElement()
jsonDecoder.json.decodeFromJsonElement(valueSerializer, jsonElement)
} catch (e: Exception) {
throwableHandler?.invoke(e)
null
}
}
}
Solution is based on answers from discussion #1205 , specifically on this and this This worked for kotlin version 1.8.10, don't know how this will work for the earlier versions.
MisterPotz hello! I have used your solution so far, and find out the following problem. When we use SafeList in nested way, like here:
@Serializable
data class Contact(
val name: String,
val phone: String
)
@Serializable
data class User(
val contacts: SafeList<Contact>
)
@Serializable
data class Response(
val result: SafeList<User>
)
So, if we try to decode json like this:
{
"result": [
{
"contacts": [
{
"name": "David",
"phone": "123"
},
{
"name": "John",
"phone": "456"
}
]
},
{
"contacts": [
{
"name": "George",
"phone": "321"
},
{
"name": "Lucas",
"phone": "654"
}
]
}
]
}
we will face strange behaviour:
kotlinx.serialization.json.internal.JsonDecodingException: Expected class kotlinx.serialization.json.JsonObject (Kotlin reflection is not available) as the serialized body of model.data.serializer.Contact, but had class kotlinx.serialization.json.JsonArray (Kotlin reflection is not available)
at kotlinx.serialization.json.internal.JsonExceptionsKt.JsonDecodingException(JsonExceptions.kt:24)
at kotlinx.serialization.json.internal.AbstractJsonTreeDecoder.beginStructure(TreeJsonDecoder.kt:358)
