GORM cascade-delete off

Question

I have three domains models Type1, Type2 and Details following the relationship below:

class Type1 {
  static hasMany = [detail: Detail]
}
class Type2 {
  static hasMany = [detail: Detail]
}
class Detail {
  Type1 type1
  Type2 type2
  static belongsTo = [Type1, Type2]
  static constraints = {
    type1(nullable:true)
    type2(nullable:true)
  }
}

The problem is that I can't get Type1.detail to be transfered to Type2.detail whenever Type1 is to be converted to Type2 (Note: Type1 and Type2 is only a child of java.lang.Object). In other words (in a controller):

Type1 type1 = Type1.get(params.id)
List type1Details = Detail.findAllByType1(type1)
type1.detail.clear()

Type2 type2 = new Type2()
// transfer other properties of type1 to type2
type1Details.each { type2.addToDetail(it) }

if(type2.save(flush:true) {
  type1.save(flush:true)
  type1.delete(flush:true)
}

The question is, only updating type1Details, how can we set type1Details*.type1 = null and type1Details*.type2 = type2?

Answer 1

After trying all the possible sequences of instructions on how to solve this problem, I end up with this working solution. From the question above, I have removed all Details related to Type1 thus deleting the record on the detail table related to Type1.detail.

Type1 type1 = Type1.get(params.id)
Type2 type2 = new Type2()

// transfer other properties of type1 to type2
type1.detail.each {
  Detail element = (Detail) it
    element.type1 = null
    element.type2 = type2
  }
type1.detail.clear()            
if(type2.save(flush:true)) {
  type1.delete(flush:true)
}

From the code above, it's clear how it is done. I know this isn't the best solution, but I can still accept better solutions.