Grails hasMany bulk create - grails

Question

I am trying to implement a "bulk" insert for hasMany. And got it 90% there, but hit a hiccup with my polyclass design. I have a model like
class Parent {
static hasMany = [references: Reference]
}
class Reference {
static belongsTo = [parent: Parent]
String name
}
class ConcreteReference extends Reference{
String childName
}
I was able to get the create working(defined by creating records) by having markup like
<form action='reference/1/edit>
<input name='references[0].name' value='name1' />
<input name='references[0].childName' value='childName1' />
<input name='references[1].name' value='name2' />
<input name='references[1].childName' value='childName2' />
</form>
But the issue is it always creates the concrete type(class='domain.Reference'), so "child name is always null.
I used:
def edit(def id){
def parent = Parent.get(id)
//i actually clear all the old references first (didn't show that code)
parent.properties = params
parent.save(flush:true)
}
How can I either specify the "concrete type"( I tried a hidden value of class it didn't work) or is there an easy way to loop through params.reference[idx] create it and then add it to Parent?
hopefully that is clear, let me know if you need any clarification.

Answer 1

My manual way of parsing params(not I hard code ConcreteReferences, but i was able to group the params):
def refRegex = /^([a-zA-Z]+\[\d+\])/
for (ref in params.groupBy { it -> it.key.find(refRegex)}.findAll{it.key}){
//this will be like references[0]: [references[0].name : 'test', etc]
//for each one create a FreeFormReference
def _ref = new ConcreteReference(ref.value.collectEntries{it -> [it.key.replace(ref.key + '.', ''), it.value]})
log.info('created reference ${_ref}')
parent.addToReferences(_ref)
}