DataModel entries appearing twice

[enrico256]

I'm writing simple CRUD application that handles I'm writing simple CRUD application that handles "folders" and associated "items". The list of all folders is displayed on the home page as following:

<h:dataTable value="#{folders}" var="_folder">
 <h:column>
 <f:facet name="header">Id</f:facet>
 <s:link action="#{folderFinder.selectFolder}" value="#{_folder.id}"/>
 </h:column>
 <h:column>
 <f:facet name="header">Title</f:facet>
 <h:outputText value="#{_folder.title}" />
 </h:column>
 ?
</h:dataTable>

"folders" are managed in a SFSB:

 ?
 @DataModel("folders")
 List<Folder> folders;

 @DataModelSelection
 @Out(required=false)
 Folder folder;

 @In(create=true) @Out(required=false)
 transient ItemFinder itemFinder;

 @Out(required=false)
 List<Item> item;

 @Factory("folders")
 public void refresh() {
 folders = em.createQuery("from Folder").getResultList();
 }

 @Begin(join=true)
 public String selectFolder() {
 itemFinder.refresh(folder); //init "items" to contain items from this folder
 return "view_folder";
 }
 ?

So far so good. My problem starts when I select a folder and display it with its items as every item appears twice in the dataTable! A folder is displayed as following :

<t:panelTabbedPane ? >
 <t:panelTab label="Folder">
 <h:panelGrid columns="2">
 <h:outputText value="Id"/>
 <h:outputText value="#{folder.id}"/>
 <h:outputText value="#Title"/>
 <h:outputText value="#{folder.title}"/>
 ?
 </h:panelGrid>
 </t:panelTab>

 <t:panelTab label="Items">
 <h:dataTable value="#{items}" var="_item" >
 <h:column>
 <f:facet name="header">Item id</f:facet>
 <s:link action="#{itemFinder.selectItem}" value="#{_item.id}"/>
 </h:column>
 <h:column>
 <f:facet name="header">Type</f:facet>
 <h:outputText value="#{_item.type}" />
 </h:column>
 ?
 </h:dataTable>
 </t:panelTab>
</t:panelTabbedPane>

"itemFinder" is a SFSB the manages "items":

 @DataModel("items")
 List<Item> items;

 @DataModelSelection
 @Out(required=false)
 Item item;

 public void refresh(Folder folder) {
 items = folder.getItems();
 }

Needless to say the database contains only one copy of each item.
I?m using Seam 1.2.1, AS 4.0.5, MySQL 5.0 and mysql-connector-3.1.13.

I would appreciate if anybody could point me in the right direction.

Thanks in advance,

Enrico

[enrico256]

Problem solved: trying to be smart the Item.setFolder method was implemented as following:

public void setFolder(Folder folder) {
 this.folder = folder;
 folder.getItems().add(this);
}

In reality item.setFolder and folder.getItems().add are called as necessary by the framework when loading objects from the db. The above implementation o f setFolder adds every item a second time resulting in a list containg every item twice. Removing the

folder.getItems().add(this);

line solved the problem :-)