Marshal / unmarshal domain instance to JSON in Grails - json

Question

I'm trying to marshal and unmarshal a domain (e.g. OrgUnit) instance as JSON to a database field like this:
class OrgUnit{
String name
OrgUnit parent
static hasMany = [children:orgUnit]
}
class History{
String data
}
class OrgUnitService{
History marshal(OrgUnit orgUnit){
return new History([
data : (orgUnit.properties as JSON).toString()
]).save()
}
OrgUnit unmarshal(History history){
return OrgUnit.newInstance( JSON.parse(history.data))
}
}
It works fine for simple fields like name, but fields like children are empty in the unmarshaled object.
The history.data field contains children information like this:
{"name":"b","children":[{"class":"demo.OrgUnit","id":3,"children":null,"name":"c"}]}
I'm using Grails 2.2.4.
Any suggestions !?
Update
I tested it on Grails 2.4.3. It works as expected. The content of the history.data field is in both Grails versions identical. The issue is in the unmarshaling part.

Answer 1

The critical part is the creation of a domain instance by properties map. It is used in the default save action in controllers. It might be a security issue in controller, but I take it out of scope there.
In Grails version 2.2.4 it doesn't bind the referencies to the instance.
The workaround there is, to do it manually like this:
class HistoryService {
def grailsApplication
History marshal(OrgUnit orgUnit) {
return new History([
data: (orgUnit.properties as JSON).toString()
]).save(failOnError: true)
}
OrgUnit unmarshal(History history) {
def data = JSON.parse(history.data)
OrgUnit instance = OrgUnit.newInstance(data)
def domainClass = grailsApplication.getDomainClass(OrgUnit.class.name)
domainClass.persistentProperties.each{p->
if (p.oneToMany || p.manyToMany){
def refDataList = data."$p.name"
refDataList.each{refData->
instance."$p.name" << getDomainClass(refData.class).read(refData.id as Long)
}
}else if (p.manyToOne || p.oneToOne){
def refData = data."$p.name"
if(refData && refData.class && refData.id){ // if reference field has value null
instance."$p.name" = getDomainClass(refData.class).read(refData.id as Long)
}
}
}
return instance
}
private def getDomainClass(String domainName){
return grailsApplication.classLoader.loadClass(domainName)
}
}