One to many mapping problem

Question

In my JPA project I'm using these three classes:
Cart.java:
package com.spinnaker.pedja;
import java.sql.Date;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.*;
@Entity(name = "Cart")
@Table(schema = "shop")
public class Cart {
     @Id
     @Column(name = "cart_id")
     private int Cart_id;
     @Column(name = "cart_date")
     private Date date;
      @OneToMany(mappedBy = "cartItemPK", targetEntity = CartItemPK.class)
      private Set cartitemCollection = new HashSet(0);
     @ManyToOne
     @JoinColumn(name = "customer_id")
     private Customer customer;
     public Customer getCustomer() {
          return customer;
     public void setCustomer(Customer customer) {
          this.customer = customer;
     public Cart() {
      public Set getCartitemCollection() {
      return cartitemCollection;
      public void setCartitemCollection(Set cartitemCollection) {
      this.cartitemCollection = cartitemCollection;
     public int getCart_id() {
          return Cart_id;
     public void setCart_id(int cart_id) {
          this.Cart_id = cart_id;
     public Date getDate() {
          return date;
     public void setDate(Date date) {
          this.date = date;
}, CartItem.java:
package com.spinnaker.pedja;
import java.io.Serializable;
import javax.persistence.*;
@Entity
@Table(schema = "shop")
public class CartItem implements Serializable {
     @EmbeddedId
     @ManyToOne
//     @JoinColumn(name = "cart_id")
     CartItemPK cartItemPK;
     @Column(name = "quantity")
     private int quantity;
     @Column(name = "unit_price")
     private double unit_price;
//     @JoinColumn(name = "cart_id")
//     private Cart cart;
//      public Cart getCart() {
//      return cart;
//      public void setCart(Cart cart) {
//      this.cart = cart;
     public CartItem() {
     public CartItemPK getCartItemPK() {
          return cartItemPK;
     public void setCartItemPK(CartItemPK cartItemPK) {
          this.cartItemPK = cartItemPK;
     public int getQuantity() {
          return quantity;
     public void setQuantity(int quantity) {
          this.quantity = quantity;
     public double getUnit_price() {
          return unit_price;
     public void setUnit_price(double unit_price) {
          this.unit_price = unit_price;
}and CartItemPK.java:
package com.spinnaker.pedja;
import java.io.Serializable;
import javax.persistence.*;
@Table(schema="shop")
@Embeddable
public class CartItemPK implements Serializable{
     @Column(name="item_id",nullable=false)
     private int itemId;
//     @ManyToOne
//     @JoinColumn(name = "cart_id")
//     private Cart cart;
     @Column(name="cart_id",nullable=false)
     private int cartId;
     public int getItemId() {
          return itemId;
     public void setItemId(int itemId) {
          this.itemId = itemId;
     public int getCartId() {
          return cartId;
     public void setCartId(int cartId) {
          this.cartId = cartId;
I'm having problem with mapping one to many relationship between Cart and CartItem.I had to introduce CartItemPK class because CartItem has composite primary key.Help please!!!

Answer 1

In my test class I'm using this code:
Cart cart=em.find(Cart.class, 33);
          Set cartItems=cart.getCartitemCollection();
          for (Iterator iterator = cartItems.iterator(); iterator.hasNext();) {
               CartItem cart_item = (CartItem) iterator.next();
               System.out.println(cart_item.getCartItemPK().getCartId());
          }and this error happens:
Exception in thread "main" javax.persistence.PersistenceException: org.hibernate.AnnotationException: Use of @OneToMany or @ManyToMany targeting an unmapped class: com.spinnaker.pedja.Cart.cartitemCollection[com.spinnaker.pedja.CartItemPK]
     at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:247)
     at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:120)
     at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:159)
     at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:95)
     at com.spinnaker.pedja.test.Test.main(Test.java:30)
Caused by: org.hibernate.AnnotationException: Use of @OneToMany or @ManyToMany targeting an unmapped class: com.spinnaker.pedja.Cart.cartitemCollection[com.spinnaker.pedja.CartItemPK]
     at org.hibernate.cfg.annotations.CollectionBinder.bindManyToManySecondPass(CollectionBinder.java:979)
     at org.hibernate.cfg.annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:530)
     at org.hibernate.cfg.annotations.CollectionBinder$1.secondPass(CollectionBinder.java:471)
     at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:43)
     at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1136)
     at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:296)
     at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1121)
     at org.hibernate.ejb.Ejb3Configuration.buildMappings(Ejb3Configuration.java:1211)
     at org.hibernate.ejb.EventListenerConfigurator.configure(EventListenerConfigurator.java:154)
     at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:847)
     at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:178)
     at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:235)
     ... 4 more
I didn't find any example on the internet about my particular case.In the database,Cart and CartItem are conected via cart_id field.But in my JPA project,cart_id field is a part of a composite key CarItemPK.