Question

class Author {

    String name

    ArrayList<Book> books = []

    static hasMany = [books: Book]

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

}

The error occurs when I try to save the object. “java.io.NotSerializableException”. Any ideas? Do I need to implement Serializable in the class? If so, why?

Answer 1

Here is the solution:

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)
      }

   }