deserialized JsonAnySetter field is null

[m-valeev]

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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.

[m-valeev]

@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.