Inheritance GORM，继承模型，递归链接

假设我们有书

class Book {

   String title
   String type="Book"
   String author
   Book parentBook // <----<<<
   //...
}

当我这样做时，当我试图为ReferenceBook设置parentBook时，会得到一个java.lang.reflect.InvocationTargetException

---

我知道我在这里遗漏了什么…

使用鉴别器功能：

  class Book {
   String title
   String author
   Book parentBook // <----<<<
   //...
   static mapping = {
     tablePerHierarchy false
     discriminator column:[name:"discriminator", length:200, value:'Book']
   }
  }

class ReferenceBook extends Book {
  //...
  static mapping = {
    discriminator column:[value:'RefBook']
  }
  void setParentBook(Book b) {
    parentBook = ('RefBook' == b?.properties['class']) ? b : null
  }

教材{
字符串标题
字符串作者
Book parentBook/使用鉴别器功能：

  class Book {
   String title
   String author
   Book parentBook // <----<<<
   //...
   static mapping = {
     tablePerHierarchy false
     discriminator column:[name:"discriminator", length:200, value:'Book']
   }
  }

class ReferenceBook extends Book {
  //...
  static mapping = {
    discriminator column:[value:'RefBook']
  }
  void setParentBook(Book b) {
    parentBook = ('RefBook' == b?.properties['class']) ? b : null
  }

教材{
字符串标题
字符串作者
书家长书//