Nested Polymorphic Deserialization using @JsonTypeInfo?

[Chuanwise Rafter]

I need to deserialize incoming packet encoded in JSON. For example, there are two kind of packet: Son and Daughter. The rules are:

1. If field "type" is not "sub",  error occurred.
2. If field "type" is "sub", checking field "sub_type":
   1. if it's "son", deserialize it as `Son`.
   2. if it's "daughter", deserialize it as `Daughter`.

According to JacksonDocs - JacksonPolymorphicDeserialization, I add annotations @JsonTypeInfo and @JsonSubTypes:

```kotlin

import com.fasterxml.jackson.annotation.JsonSubTypes
import com.fasterxml.jackson.annotation.JsonTypeInfo
import com.fasterxml.jackson.databind.PropertyNamingStrategies.SnakeCaseStrategy
import com.fasterxml.jackson.databind.annotation.JsonNaming
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
import com.fasterxml.jackson.module.kotlin.readValue
import org.junit.jupiter.api.Test

@JsonTypeInfo(
    use = JsonTypeInfo.Id.NAME,
    property = "type",
    include = JsonTypeInfo.As.PROPERTY,
    visible = true
)
@JsonSubTypes(
    JsonSubTypes.Type(Sub::class, name = "sub"),
)
@JsonNaming(SnakeCaseStrategy::class)
interface Base {
}

@JsonTypeInfo(
    use = JsonTypeInfo.Id.NAME,
    property = "sub_type",
    include = JsonTypeInfo.As.PROPERTY,
    visible = true
)
@JsonSubTypes(
    JsonSubTypes.Type(Son::class, name = "son"),
    JsonSubTypes.Type(Daughter::class, name = "daughter")
)
interface Sub : Base {
}

data class Son(
    val sonField: String
) : Sub

data class Daughter(
    val daughterField: String
) : Sub

class EventDataTest {
    private val objectMapper = jacksonObjectMapper()

    @Test
    fun testDeserializeBase() {
        val json = """
            {
              "type": "sub",
              "sub_type": "son",
              "son_field": "son"
            }
        """.trimIndent()
        val base = objectMapper.readValue<Base>(json)
    }
}

```

But exception thrown:

```

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `cn.chuanwise.onebot.lib.v11.data.event.Sub` (no Creators, like default constructor, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
 at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); line: 2, column: 11]
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1887)
at com.fasterxml.jackson.databind.DatabindContext.reportBadDefinition(DatabindContext.java:414)
at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1375)
at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserialize(AbstractDeserializer.java:274)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedForId(AsPropertyTypeDeserializer.java:170)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:136)
at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserializeWithType(AbstractDeserializer.java:263)
at com.fasterxml.jackson.databind.deser.impl.TypeWrappedDeserializer.deserialize(TypeWrappedDeserializer.java:74)
at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:342)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4905)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3848)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3831)
at cn.chuanwise.onebot.lib.v11.data.event.EventDataTest.testDeserializeBase(EventDataTest.kt:93)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:727)
at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:156)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:147)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:86)
at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(InterceptingExecutableInvoker.java:103)
at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.lambda$invoke$0(InterceptingExecutableInvoker.java:93)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.invoke(InterceptingExecutableInvoker.java:92)
at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.invoke(InterceptingExecutableInvoker.java:86)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:217)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:213)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:138)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:68)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.processAllTestClasses(JUnitPlatformTestClassProcessor.java:110)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.access$000(JUnitPlatformTestClassProcessor.java:90)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.stop(JUnitPlatformTestClassProcessor.java:85)
at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:62)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
at jdk.proxy1/jdk.proxy1.$Proxy2.stop(Unknown Source)
at org.gradle.api.internal.tasks.testing.worker.TestWorker$3.run(TestWorker.java:193)
at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)

```

[Tatu Saloranta]

On Tue, May 21, 2024 at 9:23 PM Chuanwise Rafter <rafte...@gmail.com> wrote:
>
> I need to deserialize incoming packet encoded in JSON. For example, there are two kind of packet: Son and Daughter. The rules are:
>
> If field "type" is not "sub", error occurred.
> If field "type" is "sub", checking field "sub_type":
>
> if it's "son", deserialize it as `Son`.
> if it's "daughter", deserialize it as `Daughter`.

This is not a supported use case: Type Id can only come from a single
property currently.
It won't work even if you tried using different @JsonTypeInfo in
subtypes -- it won't work as you might expect.

-+ Tatu +-

> --
> You received this message because you are subscribed to the Google Groups "jackson-user" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to jackson-user...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/jackson-user/089d7453-c8a5-405d-b96b-728c6556e103n%40googlegroups.com.

[Chuanwise Rafter]

So how to deserialize them gracefully with the help of Jackson?

[Joo Hyuk Kim (Vince)]

Try searching on Stackoverflow, keyword might be "type id resolver"

[Chuanwise Rafter]

I searched and TypeIdResolver must return a type depend on single type id, but I need type id combinations to know the final POJO class. I wrote custom deserializer but StackOverflow will be thrown because in the deserializer of `Sub`, I read field "type" and use statements like `mapper.convertValue(node, Son::class)` or `readValue(...)` to construct type will make Jackson choose the same deserializer (`ctxt.findNonContextualValueDeserializer(ctxt.constructType(Son::class.java))` is our custom deserializer of `Sub`). : (

[Joo Hyuk Kim]

Or instead of using TypeIdResolver, how about writing a custom deserializer yourself.

To view this discussion on the web visit https://groups.google.com/d/msgid/jackson-user/7fb846a4-9122-4442-8c35-b01804bb3a0cn%40googlegroups.com.

[Chuanwise Rafter]

Here is my codes :

```kotlin

@JsonTypeInfo(
    use = JsonTypeInfo.Id.CUSTOM,

    property = "type",
    include = JsonTypeInfo.As.PROPERTY,
    visible = true
)

@JsonNaming(SnakeCaseStrategy::class)
@JsonTypeIdResolver(BaseTypeIdResolver::class)
interface Base

private object BaseTypeIdResolver : TypeIdResolver {
    override fun init(baseType: JavaType?) {
        // do nothing
    }

    override fun idFromValue(value: Any): String {
        return idFromValueAndType(value, value.javaClass)
    }

    override fun idFromValueAndType(value: Any, suggestedType: Class<*>): String = when (value) {
        is Sub -> "sub"
        else -> throw IllegalArgumentException()
    }

    override fun idFromBaseType(): String {
        throw UnsupportedOperationException()
    }

    override fun typeFromId(context: DatabindContext, id: String): JavaType {
        return when (id) {
            "sub" -> context.constructType(Sub::class.java)!!
            else -> throw IllegalArgumentException()
        }
    }

    override fun getDescForKnownTypeIds(): String? {
        return null
    }

    override fun getMechanism(): JsonTypeInfo.Id {
        return JsonTypeInfo.Id.CUSTOM
    }
}

@JsonTypeInfo(
    use = JsonTypeInfo.Id.CUSTOM,

    property = "sub_type",
    include = JsonTypeInfo.As.PROPERTY,
    visible = true
)

@JsonTypeIdResolver(SubTypeIdResolver::class)
interface Sub : Base

object SubTypeIdResolver : TypeIdResolver {
    override fun init(baseType: JavaType?) {
        // do nothing
    }

    override fun idFromValue(value: Any): String {
        return idFromValueAndType(value, value.javaClass)
    }

    override fun idFromValueAndType(value: Any, suggestedType: Class<*>): String {
        return when (value) {
            is Son -> "son"
            is Daughter -> "daughter"
            else -> throw IllegalArgumentException()
        }
    }

    override fun idFromBaseType(): String {
        throw UnsupportedOperationException()
    }

    override fun typeFromId(context: DatabindContext, id: String): JavaType {
        return when (id) {
            "sub" -> context.constructType(Sub::class.java)!!
            else -> throw IllegalArgumentException()
        }
    }

    override fun getDescForKnownTypeIds(): String? {
        return null
    }

    override fun getMechanism(): JsonTypeInfo.Id {
        return JsonTypeInfo.Id.CUSTOM

    }
}


data class Son(
    val sonField: String
) : Sub

data class Daughter(
    val daughterField: String
) : Sub

```

And my test codes:

```kt

val json = """
    {
      "type": "sub",
      "sub_type": "son",
      "son_field": "son"
    }
""".trimIndent()
val base = objectMapper.readValue<Base>(json)

```

But type resolver can not using in nested, it throws:

```

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `cn.chuanwise.onebot.lib.v11.data.event.Sub` (no Creators, like default constructor, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
 at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); line: 2, column: 11]
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1887)
at com.fasterxml.jackson.databind.DatabindContext.reportBadDefinition(DatabindContext.java:414)
at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1375)
at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserialize(AbstractDeserializer.java:274)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedForId(AsPropertyTypeDeserializer.java:170)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:136)
at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserializeWithType(AbstractDeserializer.java:263)
at com.fasterxml.jackson.databind.deser.impl.TypeWrappedDeserializer.deserialize(TypeWrappedDeserializer.java:74)
at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:342)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4905)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3848)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3831)

at cn.chuanwise.onebot.lib.v11.data.event.EventDataTest.testDeserializeBase(EventDataTest.kt:194)

```

And I can't return the final POJO class Son or Daughter in the BaseTypeIdResolver. Notice that there are 2 main functions in `TypeIdResolver` called `fun idFromValueAndType(value: Any, suggestedType: Class<*>): String` and `fun typeFromId(context: DatabindContext, id: String): JavaType`, and `typeFromId` just know single type id, but we need another field "sub_type".