package filters.controllers;

import java.io.Serializable;
import javax.persistence.Query;
import org.hibernate.HibernateException;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.id.IdentifierGenerator;

import play.db.jpa.JPA;

public class CodeGenerator implements IdentifierGenerator
{
   public Serializable generate(SessionImplementor session, Object object)
           throws HibernateException
   {

      String prefix = "BAKR";
      String code = null;

      Query query = JPA.em().createNativeQuery(
              "SELECT nextval ('s_bkg1') as nextval"); //this is a Postgres sequence created manually by hand

      String result = String.valueOf(query.getResultList().get(0));
      code = prefix + "00" + result;

      return code;
   }
}

public class Booking
{
   @Id
   public int trans_pid;
   @GenericGenerator(name="bakr", strategy="filters.controllers.CodeGenerator")
   @GeneratedValue(generator="bakr")
   public String booking_no;