deserialized JsonAnySetter field is null

[MaximValeev]

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Describe the bug

I have kotlin data class

data class Request(
    @JsonProperty("header")
    override val header: String? = null,
    @JsonIgnore
    @JsonAnySetter
    @JsonAnyGetter
    val additionProperties: Map<String, Any?>? = null,
) : Parent(header)

and json

      {
            "payloadType": "perform",
            "data":{
              "header": "lol",
              "type": "sometype",
              "any_other_data": {
                  "field1": "1",
                  "field2": "",
                  "field3": "",
                  "field4": {
                      "field5": "",
                      "field6": "",
                      "field7": "anytext"
                  }
              }
            }
        }

Before jackson 2.17.0 the json deserialized into class correctly. any_other_data put to additionalProperties map.
On 2.17.0 version i have additionalProperties == null after the deserialization.

Version Information

2.17.0

Expected behavior

i expected that field annotated with @JsonAnySetter will be filled with all the undeclared fields

[JooHyukKim]

Since additionalProperties has default value of null, we can say either...

• field is deserialized to null
• field is not deserialized, so deafult to null

Could you provide Java-only reproduction to make sure it is jackson-databind issue, @MaximValeev ?
There is separate kotlin repo FYI.

[cowtowncoder]

Right; either this needs to move to jackson-module-kotlin (I can transfer if so), or reproduction should be in Java.

But I think there is probably already an issue wrt @JsonAnySetter not working with Creator properties -- and even PR to potentially fix that.

[kotcrab]

I also ran into this issue, it can be fixed by writing @field:JsonAnySetter. In 2.17.0 ElementType.PARAMETER was added to the @Target list of JsonAnySetter, this causes Kotlin to add this annotation to the constructor parameter instead of the field as described here if you don't specify explicit use-site target.

[JooHyukKim]

Ah, thank u for sharing @kotcrab !

[JooHyukKim]

Some background.

As @kotcrab described above, this is regression caused by annotations module change, the annotation change was meant to be pre-requisite for the databind-module's Allow 'JsonAnySetter' to flow through JsonCreator #562 issue.

I started writing PR #4366 to support the databind-module change, but stopped to allow room for Property Introspection Rewrite in #4515.

As per solution, either....

• revert adding ElementType.PARAMETER to JsonAnySetter or...
• ask @k163377 if it's possible to make changes so that Kotlin module can discover @JsonAnySetter without @field: declaration. Or maybe @cowtowncoder knows the proper extension point for JsonAnySetter discovery?

[cowtowncoder]

Wait, what is that @JsonIgnore doing here??!

    @JsonIgnore
    @JsonAnySetter
    @JsonAnyGetter
    val additionProperties: Map<String, Any?>? = null,

wouldn't that mean "ignore this any setter/getter"? That should not be added there.

[MaximValeev]

@cowtowncoder No, it wouldn’t. It means ignoring additionalProperties itself in serialization and deserialization. However, the other two annotations, @JsonAnySetter and @JsonAnyGetter, will be used for all unrecognized properties. All unrecognized properties will be added to the map for serialization and obtained from the map for deserialization.

[yawkat]

JsonAnyGetter/Setter will already not appear in the serialization/deserialization as its own property. The JsonIgnore is not necessary and should not be there

[cowtowncoder]

@MaximValeev it is possible @JsonIgnore does no harm, but in general it is to remove accessor (getter, setter, field, ctor parameter) from consideration (or if no inclusion, whole property).
And as @yawkat pointed out, it should not be necessary as JsonAnyGetter/Setter has priority over regular property detection.

But as to proper fix: I think #562 would be that (maybe via #4558) -- to may @JsonAnySetter work via Constructor parameter (not just Field or Method).

Alternatively, yes, Kotlin side should annotate Field to use.

[k163377]

I understood that there is nothing to do in KotlinModule as it is handled by #4558 .

[cowtowncoder]

@k163377 Yes, I think it's matter of getting #562 resolved (via #4558) and then Kotlin side probably wants to have a test to verify things work there as expected. But hopefully no other work needed (but you never know before testing :) ).

[JooHyukKim]

Caution : this is not about what has caused the change in behavior in 2.17. Instead, this is about making it work in 2.18.

So I found out that StdValueInstantiator.createFromObjectWith(DeserializationContext, SettableBeanProperty[], PropertyValueBuffer) method is overridden by KotlinValueInstantiator. I think we need some modification either on kotlin-module or databind to support this.

My intuition is that, below implementation in PropertyValueBuffer.getParameters(SettableBeanProperty[]) method...

        // [databind#562] since 2.18 : Respect @JsonAnySetter in @JsonCreator
        if (_anyParamSetter != null) {
            Object anySetterParameterObject = _anyParamSetter.createParameterObject();
            for (PropertyValue pv = _anyParamBuffered; pv != null; pv = pv.next) {
                pv.setValue(anySetterParameterObject);
            }
            _creatorParameters[_anyParamSetter.getParameterIndex()] = anySetterParameterObject;
        }

... should be moved somewhere to make it work?

[cowtowncoder]

Ideally we should remove the need for KotlinValueInstantiator overrides. But on short term, yes, may need to update override in question.

[mikethecalamity]

I'm seeing this issue when I tried to upgrade to 2.18.0, but it seems to e working fine in 2.17.2.

My class has lombok in it, but it looks like this:

@Data
public class MyClass {
    private final int id;
    private final String name;

    @JsonAnyGetter
    @JsonAnySetter
    private final Map<String, Object> params;
}

[cowtowncoder]

@mikethecalamity that is unfortunately not a full reproduction; would need to add calling code, as well as replace Lombok annotations with processed code (one JVM loads).

If this could be reproduced with plain-non-Lombok-Java that'd be great since so far assumption has been this is Kotlin-specific.
But right now we do not have such test.

[JooHyukKim]

As @kotcrab describes, this is Kotlin specific issue, but caused by FasterXML/jackson-annotations#242 in 2.17 which was to support a jackson-databind(#562) in 2.18.

[JooHyukKim]

Since this is regression, would you consider reverting FasterXML/jackson-annotations#242 in 2.17 version, @cowtowncoder? I know release is not easy, so no pressure tho.

And we may apply the annotations module change only to 2.18, try fixing things up in 2.18. If we try to fix things without change in Kotlin module, #4720 would do the fix?

[cowtowncoder]

@JooHyukKim No; annotations are special case where we really cannot change things in patch release, so 2.17.x cannot be changed except in exceptional circumstances. Same now goes for 2.18.x, actually, since 2.18.0 is released.

But if #4720 can fix this issue let's work on getting that done.
I am not opposed to changes to Kotlin module but unfortunately don't really know what to change, where and how.

I am bit worried tho about Kotlin annotation handling, wrt replication of annotations to accessors: we seem to be hitting problems related to that.

[JooHyukKim]

I am not opposed to changes to Kotlin module but unfortunately don't really know what to change, where and how.

I think we are better off not making changes to Kotlin module, as we do not strictly force using same version of databind and kotlin modules.

I am bit worried tho about Kotlin annotation handling, wrt replication of annotations to accessors: we seem to be hitting problems related to that.

Can you share some pointers that we can follow?

[cowtowncoder]

@JooHyukKim I was thinking of FasterXML/jackson-annotations#258 that had to be reverted; not sure how closely related these things are.

As to making changes to Kotlin module: agreed that coordinated changes wouldn't work. But if there was Kotlin-module-only fix (requiring no changes here), that'd be tempting.
But I don't think we have such.

[cowtowncoder]

Fix via #4720, will be in 2.18.1

[cowtowncoder]

I may be wrong but it'd look like this might be causing/dup of:

FasterXML/jackson-module-kotlin#832