Grails上的继承和数据绑定

我在对继承模型使用数据绑定时遇到问题。这是我的密码：

class Member {
   int age

   static belongsTo = [Family]
   static constraints = {}
}

class Parent extends Member {
   String name
   static constraints = {}
}

class Family {
    String name
    List members
    static hasMany = [members: Member]
    static constraints = {}
}


def test(){
    def bindingMap = [name: 'toto', members:[[age: 18, name: '1'],[age: 18]]]
    def family = new Family()
    family.properties = bindingMap
    family.save(flush: true)
    def get = Family.get(family.id)
    // here family only contains Member and no Parent, as expected...
}

正如您所看到的，使用这段代码，我无法创建具有数据绑定的父级。 有人有主意吗

谢谢