[Struts] How to populate dropdown

[Ritchie Warsi]

I decided to put this question into a thread of its own to keep things clear.
I now know the jsp part of dropdown lists (static options), but now I want to add dynamic values. I understand this can be done with a collection bean, but how exactly?

I'm using Struts w/ Hibernate and I am able to do simple inserts and retrievals from the database (select * from..).

ComponentService.java contains:

public Component getComponent(Long id)
{
/*
 * Use the ConnectionFactory to retrieve an open
 * Hibernate Session.
 * 
 */
Session session = null;
 
try
{
session = HibernateUtil.getSession();
/*
 * Calls the load method on the Hibernate session object
 * to retrieve the Item with the provided id.
 */
return (Component) session.load(Component.class, id);
}
/*
 * If the object is not found, i.e., no Item exists with the
 * requested id, we want the method to return null rather 
 * than throwing an Exception.
 * 
 */
catch (ObjectNotFoundException onfe)
{
return null;
}
catch (HibernateException e)
{
/*
 * All Hibernate Exceptions are transformed into an unchecked
 * RuntimeException.  This will have the effect of causing the
 * user's request to return an error.
 * 
 */
System.err.println("Hibernate Exception" + e.getMessage());
throw new RuntimeException(e);
}
/*
 * Regardless of whether the above processing resulted in an Exception
 * or proceeded normally, we want to close the Hibernate session.  When
 * closing the session, we must allow for the possibility of a Hibernate
 * Exception.
 * 
 */
finally
{
if (session != null)
{
try
{
session.close();
}
catch (HibernateException e)
{
System.err.println("Hibernate Exception" + e.getMessage());
throw new RuntimeException(e);
}
 
}
}
 
}
 
/**
 * getItemList() returns list of all <code>Item</code> objects stored in the database. 
 * 
 * @return <code>List</code> of <code>Item</code> objects.
 */
public List getComponentList()
{
/*
 * Use the ConnectionFactory to retrieve an open
 * Hibernate Session.
 * 
 */
Session session = null;
 
try
{
session = HibernateUtil.getSession();
/*
* Build HQL (Hibernate Query Language) query to retrieve a list
* of all the items currently stored by Hibernate.
 */
Query query =
session.createQuery(
"select Component from com.frontier.hibernate.Component Component order by Component.cdComponent");
return query.list();
 
}
catch (HibernateException e)
{
System.err.println("Hibernate Exception" + e.getMessage());
throw new RuntimeException(e);
}
/*
 * Regardless of whether the above processing resulted in an Exception
 * or proceeded normally, we want to close the Hibernate session.  When
 * closing the session, we must allow for the possibility of a Hibernate
 * Exception.
 * 
 */
finally
{
if (session != null)
{
try
{
session.close();
}
catch (HibernateException e)
{
System.err.println("Hibernate Exception" + e.getMessage());
throw new RuntimeException(e);
}
 
}
}
}

The getComponentList i use in my JSP file to show all the values in my Component table

List componentList = ComponentService.getInstance().getComponentList();
request.setAttribute("components", componentList);
...
...
<logic:iterate id="element" name="components" scope="request" type="com.frontier.hibernate.Component" indexId="toggle">
   
   <tr>
   <td class="td1"><bean:write name="element" property="idComponent" /></td>
      <td class="td1"><bean:write name="element" property="cdComponent" /></td> 
      <td class="td1"><bean:write name="element" property="omschrijving" /></td>
      <td class="td1"><bean:write name="element" property="langeOmschrijving" /></td>
      <td class="td1"><bean:write name="element" property="indBedragwaarde" /></td>
      <td class="td1"><bean:write name="element" property="indPrint" /></td>
      <td class="td1"><bean:write name="element" property="indSubcomponent" /></td>
   </tr>

My Action class is called AddComponent.java and my formbean class is called ComponentForm.java

So where and most importantly how do i make the collection and can I use one of the two methods above in my ComponentService?

[Kedar Dravid]

U would create the ArrayList in an Action class ans set it as a request attribute. In ur JSP page, u can use the <html ptions> tag to populate the dropdown. The value of the collection attribute of the tag would be the name of thwe request atribute.

[Ritchie Warsi]

Hey there, tnx.
I know that can be done that way, but how. I've done this before but not "the struts way":

public static Functie getFunctie(int aFunctieId) {
 return (Functie) functieList.get(new Integer(aFunctieId));
 }
 
 /**
  * static init
  * lees alle elementen uit de database
  */
 static
 {
functieList = new HashMap();
Connection con = null;
try {
con = DB.getConnection();
String sqlQuery =
"select" +
"f.functie_id functie_id," +
"f.naam naam" +
"from" +
"functie f";
PreparedStatement pstmt = con.prepareStatement(sqlQuery);
ResultSet rs = pstmt.executeQuery();
while (rs.next()) {
Functie f = new Functie();
f.functieId = rs.getInt("functie_id");
f.naam = rs.getString("naam");
functieList.put(new Integer(f.functieId), f);
}
}
catch (SQLException se) {
System.err.println("Error reading functies : " + se.getMessage());
}
finally {
try {
if (con != null) {
con.close();
}
}
catch (SQLException se1) {}
}
}
}

But now I'm using Struts (organized java classes), Hibernate and wanna put it in a collection.
So does anyone have a example of such a source?

[Jason Menard]

Ritchie W.,

Welcome to JavaRanch. We don't have many rules here, but this is a moderated forum and we do have a strict naming policy. Please re-read this policy and edit your display name in order to comply. Thanks and we look forward to seeing around the 'Ranch.

[Ritchie Warsi]

*Bump*
Anyone?..