CRUD with a OneToMany association under Struts 2 / Hibernate 3

[bruno grandjean]

Hi

I am trying to implement a simple CRUD with a OneToMany association under 
Struts 2 / Hibernate 3.
I have two entities Parent and Child:

@Entity
@Table(name="PARENT")
public class Parent {
 private Long id;
 private Set<Child> values = new HashSet<Child>();  
..
@Entity
@Table(name="CHILD")
public class Child {
 private Long id; 
 private String name; 
..

I can easily create, delete Parent or read the Child Set (values) but it is 
impossible to update Child Set.
The jsp page (see below) reinit the values Set, no record after updating!
Could u explain to me what's wrong?

here are my code:

@Entity
@Table(name="PARENT")
public class Parent {
 private Long id;
 private Set<Child> values = new HashSet<Child>();  
 @Id
 @GeneratedValue
 @Column(name="PARENT_ID") 
 public Long getId() {
  return id;
 }
 public void setId(Long id) {
  this.id = id;
 }
 @ManyToMany(fetch = FetchType.EAGER)    
 @JoinTable(name = "PARENT_CHILD", joinColumns = { @JoinColumn(name = 
"PARENT_ID") }, inverseJoinColumns = { @JoinColumn(name = "CHILD_ID") })  
 public Set<Child> getValues() {  
  return values;
 }
 public void setValues(Set<Child> lst) {
  values = lst;  
 }
}

@Entity
@Table(name="CHILD")
public class Child {
 private Long id; 
 private String name; 
 @Id
 @GeneratedValue
 @Column(name="CHILD_ID") 
 public Long getId() {
  return id;
 }
 public void setId(Long id) {
  this.id = id;
 }
 @Column(name="NAME")
 public String getName() {  
  return name;
 }
 public void setName(String val) {
  name = val;
 } 
}

public interface ParentDAO {
 public void saveOrUpdateParent(Parent cl);
 public void saveParent(Parent cl);
 public List<Parent> listParent();
 public Parent listParentById(Long clId);
 public void deleteParent(Long clId);
}

public class ParentDAOImpl implements ParentDAO {
 @SessionTarget
 Session session;
 @TransactionTarget
 Transaction transaction;

 @Override
 public void saveOrUpdateParent(Parent cl) {  
  try {
   session.saveOrUpdate(cl);
  } catch (Exception e) {
   transaction.rollback(); 
   e.printStackTrace();
  }
 }

 @Override
 public void saveParent(Parent cl) {
  try {
   session.save(cl);
  } catch (Exception e) {
   transaction.rollback();
   e.printStackTrace();
  }
 }
 
 @Override
 public void deleteParent(Long clId) {
  try {
   Parent cl = (Parent) session.get(Parent.class, clId);
   session.delete(cl);
  } catch (Exception e) {
   transaction.rollback();
   e.printStackTrace();
  } 
 }
 
 @SuppressWarnings("unchecked")
 @Override
 public List<Parent> listParent() {
  List<Parent> courses = null;
  try {
   courses = session.createQuery("from Parent").list();
   } catch (Exception e) {
   e.printStackTrace();
  }
  return courses;
 }

 @Override
 public Parent listParentById(Long clId) {
  Parent cl = null;
  try {
   cl = (Parent) session.get(Parent.class, clId);
  } catch (Exception e) {
   e.printStackTrace();
  }
  return cl;
 }
}

public class ParentAction  extends ActionSupport implements ModelDriven<Parent> 
{

 private static final long serialVersionUID = -2662966220408285700L;
 private Parent cl = new Parent();
 private List<Parent> clList = new ArrayList<Parent>(); 
 private ParentDAO clDAO = new ParentDAOImpl();
 
 @Override
 public Parent getModel() {
  return cl;
 }
 
 public String saveOrUpdate()
 {
  clDAO.saveOrUpdateParent(cl);  
  return SUCCESS;
 }

 public String save()
 {  
  clDAO.saveParent(cl);  
  return SUCCESS;
 }

 public String list()
 {
  clList = clDAO.listParent();
  return SUCCESS;
 }
 
 public String delete()
 {
  HttpServletRequest request = (HttpServletRequest) 
ActionContext.getContext().get(ServletActionContext.HTTP_REQUEST);
  clDAO.deleteParent(Long.parseLong(request.getParameter("id")));
  return SUCCESS;
 }

 public String edit()
 {
  HttpServletRequest request = (HttpServletRequest) 
ActionContext.getContext().get(ServletActionContext.HTTP_REQUEST);
  cl = clDAO.listParentById(Long.parseLong(request.getParameter("id")));
  return SUCCESS;
 }
 
 public Parent getParent() {
  return cl;
 }

 public void setParent(Parent cl) {
  this.cl = cl;
 }

 public List<Parent> getParentList() {
  return clList;
 }

 public void setParentList(List<Parent> clList) {
  this.clList = clList;
 }
}

and finally the jsp page:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
"http://www.w3.org/TR/html4/loose.dtd";>
<%...@taglib uri="/struts-tags" prefix="s"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Parent Registration Page</title>
<s:head />
<style type="text/css">
@import url(style.css);
</style>
</head>
<body>
<s:form action="saveOrUpdateParent">
 <s:push value="parent">
  <s:hidden name="id" />  
   <s:push value="values">
   <s:iterator id="p" value="values">
   <s:textfield label="Nom" name="values(%{id}).name" value="%{name}"/>
        </s:iterator>
  </s:push>
    <s:submit />
 </s:push>
</s:form>

<s:if test="parentList.size() > 0">
 <div class="content">
 <table class="userTable" cellpadding="5px">
  <tr class="even">
   <th>Child(s)</th>
  </tr>
  <s:iterator value="parentList" status="userStatus">
   <tr
    class="<s:if test="#userStatus.odd == true 
">odd</s:if><s:else>even</s:else>">
    <td><s:property value="values.size()" /></td>
    <s:iterator value="values">
     <td><s:property value="name" /></td>
    </s:iterator>
    <td><s:url id="editURL" action="editParent">
     <s:param name="id" value="%{id}"></s:param>
    </s:url> <s:a href="%{editURL}">Edit</s:a></td>
    <td><s:url id="deleteURL" action="deleteParent">
     <s:param name="id" value="%{id}"></s:param>
    </s:url> <s:a href="%{deleteURL}">Delete</s:a></td>
   </tr>
  </s:iterator>
 </table>
 </div>
</s:if>
</body>
</html>