@JsonProperty and @JsonIdentityInfo require ordered data

[bsmulders]

I use @JsonProperty and @JsonIdentityInfo to link a child and parent object together. This works, but I have to re-arange the JSON string before I feed it to jacksonObjectMapper.readValue() to avoid a UnresolvedForwardReference exception. There is no cyclic dependency between the two objects, the child only refers to the parent, not the other way around.

A complete and standalone testcase is attached below. Note how I changed the order of the "parents" and "children" elements around in the JSON string.

import com.fasterxml.jackson.annotation.JsonIdentityInfo
import com.fasterxml.jackson.annotation.JsonProperty
import com.fasterxml.jackson.annotation.ObjectIdGenerators
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
import com.fasterxml.jackson.module.kotlin.readValue

data class Family(val children: List<Child>, val parents: List<Parent>)

data class Child(val id: Long, val name: String, @JsonProperty("parentID") val parent: Parent)

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator::class, property = "id")
data class Parent(val id: Long, val name: String)

fun main(args: Array<String>) {
    val orderedJson = """
{
  "parents": [
    {
      "name": "Matthew",
      "id": 101
    },
    {
      "name": "Sandra",
      "id": 102
    }
  ],
  "children": [
    {
      "name": "Peter",
      "id": 201,
      "parentID": 101
    },
    {
      "name": "Eva",
      "id": 202,
      "parentID": 101
    },
    {
      "name": "Dave",
      "id": 203,
      "parentID": 102
    }
  ]
}
    """

    val orderedFamily: Family = jacksonObjectMapper().readValue(orderedJson)

    println(orderedFamily.children.get(0).name)
    println(orderedFamily.children.get(0).id)
    println(orderedFamily.children.get(0).parent.name)

    val unorderedJson = """
{
  "children": [
    {
      "name": "Peter",
      "id": 201,
      "parentID": 101
    },
    {
      "name": "Eva",
      "id": 202,
      "parentID": 101
    },
    {
      "name": "Dave",
      "id": 203,
      "parentID": 102
    }
  ],
  "parents": [
    {
      "name": "Matthew",
      "id": 101
    },
    {
      "name": "Sandra",
      "id": 102
    }
  ]
}
    """

    val unorderedFamily: Family = jacksonObjectMapper().readValue(unorderedJson)

    println(unorderedFamily.children.get(0).name)
    println(unorderedFamily.children.get(0).id)
    println(unorderedFamily.children.get(0).parent.name)

}

Output:

Peter
201
Matthew
Exception in thread "main" com.fasterxml.jackson.databind.deser.UnresolvedForwardReference: Could not resolve Object Id [101] (for [simple type, class com.bsmulders.onverhardkaardgenerator.Parent]).
 at [Source: (String)"
{
  "children": [
    {
      "name": "Peter",
...

[k163377]

Issues last updated before 2020 are closed.
If the problem is reproduced in the latest version, please reopen.