Author.scala

package net.liftweb.example.model

import javax.persistence._
import com.google.appengine.api.datastore.Key

@Entity
class Author {
  @Id
  @GeneratedValue(){val strategy = GenerationType.IDENTITY}
  var id : Key = _

  @Column{val nullable = false}
  var name : String = ""

  @OneToMany{val mappedBy = "author", val targetEntity=classOf[Book]}
  var books : java.util.List[Book] = _
}

Book.scala

package net.liftweb.example.model

import com.google.appengine.api.datastore.Key

import java.util.Date
import javax.persistence._
import org.hibernate.annotations.Type

@Entity
class Book {
  @Id
  @GeneratedValue(){val strategy = GenerationType.IDENTITY}
  var id : Key = _

  @Column{val nullable = false}
  var title : String = ""

  @Column{val nullable = true}
  var published : Date = new Date()

  @Column{val nullable = true}
  var genre : String = "unknown"                    
                                     
  @Column{val nullable = false}
  @ManyToOne
  var author : Author = _
}