Jackson property annotations are not working with data classes

[AAverin]

@JsonUnwrapped annotations are not working for data classes failing with not find creator property with name 'propertyname'.
Same structure with a regular class seems to work fine.

[apatrida]

can you please provide a small failing test case, thanks

[AAverin]

Sorry, was on a vacation. Here's the test

import com.fasterxml.jackson.annotation.JsonInclude
import com.fasterxml.jackson.annotation.JsonUnwrapped
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
import org.junit.Before
import org.junit.Test

data class TestGalleryWidget(
        val widgetReferenceId: String,
        @JsonUnwrapped var gallery: TestGallery
)

@JsonInclude(JsonInclude.Include.NON_EMPTY)
data class TestGallery(
        val id: String? = null,
        val headline: String? = null,
        val intro: String? = null,
        val role: String? = null,
        val images: List<TestImage>? = null
)

@JsonInclude(JsonInclude.Include.NON_EMPTY)
data class TestImage(
        val id: String? = null,
        val escenicId: String? = null,
        val caption: String? = null,
        val copyright: String? = null,
        val crops: Map<String, String>? = null
)

class JacksonModuleKotlinTest {

    lateinit var mapper: ObjectMapper
    val gallery = TestGallery(
        id = "id",
        headline = "headline",
        intro = "intro",
        role = "role",
        images = listOf(
                TestImage(id = "testImage1"),
                TestImage(id = "testImage2")
        )
    )
    val validJson = """
{"widgetReferenceId":"widgetReferenceId","id":"id","headline":"headline","intro":"intro","role":"role","images":[{"id":"testImage1"},{"id":"testImage2"}]}
    """

    @Before
    fun setUp() {
        mapper = jacksonObjectMapper()
    }

    @Test
    fun serializes() {
        val result = mapper.writeValueAsString(TestGalleryWidget("widgetReferenceId", gallery))
        println(result)
    }

    @Test
    fun deserializes() {
        val result = mapper.readValue(validJson, TestGalleryWidget::class.java)
        println(result)
    }
}

[AAverin]

deserializes test fails with:

com.fasterxml.jackson.databind.JsonMappingException: Could not find creator property with name 'gallery' (in class de.weltn24.natives.arnold.TestGalleryWidget)
 at [Source: 
{"widgetReferenceId":"widgetReferenceId","id":"id","headline":"headline","intro":"intro","role":"role","images":[{"id":"testImage1"},{"id":"testImage2"}]}
    ; line: 2, column: 1]

	at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:270)
	at com.fasterxml.jackson.databind.DeserializationContext.reportMappingException(DeserializationContext.java:1234)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.addBeanProps(BeanDeserializerFactory.java:551)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.buildBeanDeserializer(BeanDeserializerFactory.java:226)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.createBeanDeserializer(BeanDeserializerFactory.java:141)
	at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer2(DeserializerCache.java:403)
	at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer(DeserializerCache.java:349)
	at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:264)
	at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCacheValueDeserializer(DeserializerCache.java:244)
	at com.fasterxml.jackson.databind.deser.DeserializerCache.findValueDeserializer(DeserializerCache.java:142)
	at com.fasterxml.jackson.databind.DeserializationContext.findRootValueDeserializer(DeserializationContext.java:476)
	at com.fasterxml.jackson.databind.ObjectMapper._findRootDeserializer(ObjectMapper.java:3899)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3794)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2842)
	at de.weltn24.natives.arnold.JacksonModuleKotlinTest.deserializes(JacksonModuleKotlinTest.kt:64)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:253)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:84)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

[apatrida]

Thanks, looking at it now.

[apatrida]

The issue is obscured in older versions of Jackson, with 2.9 you now get the correct error:

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Can not define Creator parameter 1 as `@JsonUnwrapped`: combination not yet supported
 at [Source: 
{"widgetReferenceId":"widgetReferenceId","id":"id","headline":"headline","intro":"intro","role":"role","images":[{"id":"testImage1"},{"id":"testImage2"}]}
    ; line: 2, column: 1]

Databind does not support JsonUnwrapped being used in a constructor or static creator method, it expects a 1-to-1 relationship between incoming parameters and available creator parameters. A solution would be to move that one property into the body of the class as a lateinit property. I show the bad, and good versions here in a test case added for this issue:

https://github.com/FasterXML/jackson-module-kotlin/blob/master/src/test/kotlin/com/fasterxml/jackson/module/kotlin/test/Github56.kt

[sgrimm-sg]

A workaround for this, in case anyone arrives at this issue while searching for a solution to the problem: Change @JsonUnwrapped to @field:JsonUnwrapped, which will move the annotation to the field (instead of the constructor parameter) where Jackson will see it and correctly interpret it.

[cowtowncoder]

This would suggest that there might be something wrong (or missing) with constructor parameter usage, or discovery. In theory unwrapped should work in either place, but if constructor is not visible for some reason then this could follow.

[nanodeath]

Thanks @sgrimm-sg, that helped me out as well. I'm not even using data classes, but I am annotating a constructor property as @JsonUnwrapped -- as far as I can tell, @JsonUnwrapped must always be @field:JsonUnwrapped. I forgot to call registerKotlinModule() in my test! /facepalm nevermind...

[mjstewart]

I couldn't get @field:JsonUnwrapped to work. It works fine for serializing but not for deserializing.

To summarize what works and what doesn't.

This wont work
Naturally this is what you would think would work

@Embeddable
data class Sku(val sku: String)

@Entity
data class Product(@field:JsonUnwrapped val sku: Sku) {
    @field:[Id GeneratedValue(strategy = GenerationType.AUTO)]
    val id: Long? = null
}

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot define Creator property "sku" as @JsonUnwrapped: combination not yet supported

1. hack to make it work
This is the next best choice for it to work but is messy.

@Embeddable
data class Sku(val sku: String)

@Entity
data class Product(@field:JsonIgnore val sku: Sku) {
    @field:[Id GeneratedValue(strategy = GenerationType.AUTO)]
    val id: Long? = null

    @get:JsonUnwrapped
    private val _sku: Sku
        get() = sku
}

2. use lateinit

I don't consider this a solution as it violates the proper way to instantiate an object. For example, if the constructor has all value objects (non primitives) then you need to put in a dummy property placeholder for it to work with a data class.

@Embeddable
data class Sku(val sku: String)

@Entity
data class Product(val dummyPropertyToMakeThisWork: String) {
    @field:[Id GeneratedValue(strategy = GenerationType.AUTO)]
    val id: Long? = null

    @JsonUnwrapped lateinit var sku: Sku
}

[javenwang]

1. hack to make it work
This is the next best choice for it to work but is messy.

@Embeddable
data class Sku(val sku: String)

@Entity
data class Product(@field:JsonIgnore val sku: Sku) {
    @field:[Id GeneratedValue(strategy = GenerationType.AUTO)]
    val id: Long? = null

    @get:JsonUnwrapped
    private val _sku: Sku
        get() = sku
}

it does not work for deserializing neither. here is my code:

data class Child(val name: String)

data class Parent(@field:JsonIgnore val child: Child) {
    @get:JsonUnwrapped
    private val _child: Child
        get() = child
}

error message:

java.lang.IllegalArgumentException: Instantiation of [simple type, class com.example.Parent] value failed for JSON property key due to missing (therefore NULL) value for creator parameter key which is a non-nullable type
 at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.example.Parent["child"])

	at com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:3750)
	at com.fasterxml.jackson.databind.ObjectMapper.convertValue(ObjectMapper.java:3668)
	at io.vertx.core.json.JsonObject.mapTo(JsonObject.java:106)
	at com.example.AppTest.json unwrap deserialize(AppTest.kt:106)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: com.fasterxml.jackson.module.kotlin.MissingKotlinParameterException: Instantiation of [simple type, class com.example.Parent] value failed for JSON property key due to missing (therefore NULL) value for creator parameter key which is a non-nullable type
 at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.example.Parent["child"])
	at com.fasterxml.jackson.module.kotlin.KotlinValueInstantiator.createFromObjectWith(KotlinValueInstantiator.kt:107)
	at com.fasterxml.jackson.databind.deser.impl.PropertyBasedCreator.build(PropertyBasedCreator.java:195)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeUsingPropertyBased(BeanDeserializer.java:488)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1287)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:326)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159)
	at com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:3745)
	... 25 more

it seems that we have to use normal class for Parent rather than data class

class Parent {
    @JsonUnwrapped
    lateinit var child: Child
}

[hotzen]

i have only found the following "hack" to work properly and without too much dummy-fields-foobar:

data class Foobar @JsonCreator(mode = JsonCreator.Mode.DELEGATING) constructor(@JsonValue val value: String) {
...
}

coming from #91 (comment)

[abhilashmandaliya]

You saved my day @hotzen ! Thanks

[mellosti]

I am using second constructor with @JsonCreator as workaround:

data class Child(val name: String)

data class Parent(@field:JsonUnwrapped val child: Child) {
   @JsonCreator
   constructor(name: String): this(Child(name))
}

[wingsofovnia]

While looking for a stop-gap solution for this in GitHub, I found this (usage) rather straightforward solution for @JsonUnwrapped support in Kotlin data classes without any need in adjusting fields/annotations. Support in creators is being worked on here: FasterXML/jackson-databind#1467 (PR: FasterXML/jackson-databind#4271).

[robsonhermes]

The issue is obscured in older versions of Jackson, with 2.9 you now get the correct error:

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Can not define Creator parameter 1 as `@JsonUnwrapped`: combination not yet supported
 at [Source: 
{"widgetReferenceId":"widgetReferenceId","id":"id","headline":"headline","intro":"intro","role":"role","images":[{"id":"testImage1"},{"id":"testImage2"}]}
    ; line: 2, column: 1]

Databind does not support JsonUnwrapped being used in a constructor or static creator method, it expects a 1-to-1 relationship between incoming parameters and available creator parameters. A solution would be to move that one property into the body of the class as a lateinit property. I show the bad, and good versions here in a test case added for this issue:

https://github.com/FasterXML/jackson-module-kotlin/blob/master/src/test/kotlin/com/fasterxml/jackson/module/kotlin/test/Github56.kt

@apatrida Not sure if I missed something in your suggestion, but I tried an attribute inside the body of the data class, but didn't work. Tried in both data classes and "regular classes". When I add an @JsonUnwrapped attribute, the other fields from the body stop being deserialized:

@JsonIgnoreProperties(ignoreUnknown = true)
data class Foobar(
    val foo: String,
)  {
    var bar: String? = null

    @JsonUnwrapped
    var unwrappedFoobar: UnwrappedFoobar? = null

    data class UnwrappedFoobar(
        var unwrappedFoobar: String
    )
}

If I try to deserialize this Json:

        {
            "foo": "this is foo",
            "bar": "this is bar",
            "unwrappedFoobar": "this is unwrappedFoobar"
        }

Then the bar attribute will be null :(
As per my tests, everything in the body must be either wrapped or unwrapped. If you mix both, it doesn't deserialize the unwrapped ones. Serialization is fine. Is this a different issue? If yes I can open a separate one.