grails - java.io.NotSerializableException将hasMany更改为ArrayList

Question

class Author {

    String name

    ArrayList<Book> books = []

    static hasMany = [books: Book]

    static mapping = {
      books cascade: "all-delete-orphan"
    }

}

当我尝试保存对象时发生错误。 “java.io.NotSerializableException”。有任何想法吗？我需要在该类中实现Serializable吗？如果是这样，为什么？

Answer 1

解决方法如下:

class Author {

    String name

    SortedSet books

    static hasMany = [books: Book]

    static mapping = {
      books cascade: "all-delete-orphan"
    }

}

   class Book implements Comparable {
      String title

      static belongsTo = [author: Author]

      int compareTo(obj) {
        title.compareTo(obj.title)
      }

   }