Json deserialization of class with no default constructor and referenced field in the provided constructor

[larjohn]

Hi,

I am using mysema QueryDSL for persistence-ORM functionality. I would like to store built query objects together in JSON format, so that I can load and reuse them. As most of the classes in QueryDSL are abstract, and I would not modify them, I have used mixins to configure their JSON serialization/deserialization:

My issue is with the PathMetadata mixin. The original PathMetadata class can be seen here:

https://github.com/querydsl/querydsl/blob/master/querydsl-core/src/main/java/com/querydsl/core/types/PathMetadata.java

The mixin that I have created for this class is the following:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.mysema.query.types.Path;
import com.mysema.query.types.PathType;

import javax.annotation.Nullable;

public abstract class PathMetadataMixin {

@JsonProperty
private Path<?>parent;

@JsonIgnore
private Path<?>root;


@JsonCreator
public PathMetadataMixin(@JsonProperty("parent")  @Nullable Path<?> parent, @JsonProperty("element") Object element, @JsonProperty("type") PathType type ) {

}

}

When I serialize an instance of this PathMetadata class, everything works as expected and it is outputted either as a whole, or with the ref attribute if it is already there. But when I try to deserialize the object, it throws a crypric exception:

Caused by: java.lang.ArrayStoreException: com.fasterxml.jackson.databind.deser.impl.ObjectIdReferenceProperty

I have found that this exception is fired here:

/com/fasterxml/jackson/core/jackson-databind/2.6.0-rc1/jackson-databind-2.6.0-rc1-sources.jar!/com/fasterxml/jackson/databind/deser/BeanDeserializerBase.java:485

Actually, in this line

creatorProps[i] = prop;

creatorProps is an array of CreatorProperty objects (although it is declared more generally) and prop is an ObjectIdReferenceProperty. Thus it cannot be added to the array.

How can I solve this?

[stickfigure]

This goes beyond my Jackson knowledge, but it also doesn't seem to be JSOG-related. Perhaps you wish to ask this question on the jackson mailing list?

[larjohn]

This issue was moved to FasterXML/jackson-databind#874