Some code: package auction.beans; | | import org.jboss.seam.annotations.*; | import org.jboss.seam.annotations.datamodel.DataModel; | import org.jboss.seam.annotations.datamodel.DataModelSelection; | import org.jboss.seam.ScopeType; | import org.hibernate.ejb.HibernateEntityManager; | | import javax.ejb.Stateful; | import javax.ejb.Remove; | import javax.persistence.EntityManager; | | import auction.model.Category; | import auction.model.Item; | import auction.dao.CategoryDAO; | import auction.interceptors.LoggedIn; | | import java.util.*; | | /** | * A conversational component for browsing the catalog. | * | * When the first variable for "catalog" has to be resolved, this component is | * instantiated and a conversation begins. All root categories (with no parent) | * of the catalog are loaded immediately and held during the conversation. | * | * When a category is selected, the selected value is passed into the method | * setSelectedCategory(category) manually, this is the easiest way to get the | * value of a click from a Trinidad tree JSF component. | * | * The item list is loaded when a category is selected and outjected into a | * data model for display. When a user triggers an action in the data model's | * table, the selectedItem of this conversation is set. | * | * The conversation ends usually by timeout or when it is destroyed | * with one of Seams UI conversation management switchers/lists. | * | * @author Christian Bauer | */ | @Name("catalog") | @Scope(ScopeType.CONVERSATION) // Redundant, a SFSB is default in conversation context | | @LoggedIn // Wrap LoginInterceptor around every method call | | @Stateful | public class CatalogBean implements Catalog { | | // We don't call the EntityManager directly in this bean (except to flush), only the DAOs. | // But the DAOs are not always called in every method that does data access. For example, | // when setSelectedCategory() is called, the categoryDAO is injected into this bean, | // but the persistence context is not set on the categoryDAO (because no method is | // called on the DAO, we just load a collection on-demand). So the persistence context | // doesn't join the JTA transaction, which means it doesn't get flushed when | // setSelectedCategory() returns (no synchronization registered). Short story: The | // persistence context needs to be injected managed here, so that lazy loading works | // properly in all methods of this stateful bean. | @In(value = "caveatEmptorEM", create = true) | private EntityManager em; | | // A stateless (yes, even for them create="true" is required) DAO component injected by Seam | @In(create = true) | private CategoryDAO categoryDAO; | | // This bean holds the root categories during a conversation | private List<Category> rootCategories; | | // If present, Seam outjects this into the 'currentCategory' CONVERSATION variable | @In(required = false) | @Out(required = false, scope = ScopeType.CONVERSATION) | private Category currentCategory; | | // Seam outjects this always to the 'itemList" CONVERSATION variable as a JSF DataModel | @DataModel | private List<Item> itemList; | | /** | * Seam calls this when the Catalog bean is instantiated for a particular CONVERSATION. | * Seam will start a long-running conversation when this method is called. | */ | @Create | @Begin(flushMode = FlushModeType.MANUAL) | public void refreshRootCategories() { | rootCategories = categoryDAO.findAll(true); | } | | public List<Category> getRootCategories() { | return rootCategories; | } | | /** | * Loads the selected category's items into a data model that is then outjected. | * @param selectedCategory | */ | public void setSelectedCategory(Category selectedCategory) { | // Prepare the member variable for outjection | currentCategory = selectedCategory; | // Refresh the itemList (wrap the Set in a List, no pre-defined or database sorting) | itemList = new ArrayList<Item>(currentCategory.getItems()); | } | | @Remove @Destroy @End | public void closeCatalog() { | // Nothing to do here, Seam will close the managed persistence context when | // this method returns. | } | | } | | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> | <ui:composition xmlns="http://www.w3.org/1999/xhtml" | xmlns:ui="http://java.sun.com/jsf/facelets" | xmlns:h="http://java.sun.com/jsf/html" | xmlns:f="http://java.sun.com/jsf/core" | xmlns:tr="http://myfaces.apache.org/trinidad" | xmlns:s="http://jboss.com/products/seam/taglib" | template="template.xhtml"> | | <ui:define name="screen">Catalog</ui:define> | | <ui:define name="sidebar"> | | <h1>#{messages['AuctionCategories']}:</h1> | | <tr:form> | <!-- Let Trinidad inject the selected category into our conversation component --> | <!-- Trinidad tree icons are really really ugly (HTML entities), there is no way to change them... --> | <tr:tree var="cat" value="#{catalogCategoryAdapter.treeModel}"> | <f:facet name="nodeStamp"> | <tr:commandLink text="#{cat.name}" styleClass="nodeText"> | <tr:setActionListener from="#{cat}" to="#{catalog.selectedCategory}"/> | </tr:commandLink> | </f:facet> | </tr:tree> | | </tr:form> | | </ui:define> | | <ui:define name="content"> | | <!-- Headline --> | <div class="section"> | <h1> | <!-- Read the event context variable "currentCategory" that was outjected by our conversation component --> | <h:outputText value="#{messages['PleaseSelectCategory']}" rendered="#{currentCategory == null}"/> | <h:outputText value="#{messages['SelectedCategory']}: #{currentCategory.name}" rendered="#{currentCategory != null}"/> | </h1> | </div> | | <!-- Item table --> | <div class="section"> | <!-- Read the conversation context variable "itemList", outjected by the catalog conversation component --> | <h:outputText value="#{messages['NoItemsInCategory']}" | rendered="#{itemList != null and itemList.rowCount==0}"/> | | <h:form> | <h:dataTable value="#{itemList}" var="itm" rendered="#{itemList.rowCount>0}"> | <h:column> | <f:facet name="header">#{messages['ItemName']}</f:facet> | #{itm.name} | </h:column> | <h:column> | <f:facet name="header">#{messages['ItemDescription']}</f:facet> | #{itm.description} | </h:column> | <h:column> | <f:facet name="header">#{messages['ItemSeller']}</f:facet> | #{itm.seller.username} | </h:column> | <h:column> | <f:facet name="header">#{messages['Action']}</f:facet> | <s:link value="#{messages['PlaceBid']}" styleClass="button" action="#{placeBid.selectItem(itm)}"/> | </h:column> | </h:dataTable> | </h:form> | | </div> | | </ui:define> | | </ui:composition> | View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3978857#... 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