[jboss-user] [EJB 3.0] - failed to lazily initialize a collection of role: mall.entit

[jojof]

hi

I have two entity Beans

@Entity
@Table(name = "items")
public class Item implements Serializable {
...
@ManyToOne
	@JoinColumn(name = "CATEGORY_ID")
	public Category getCategory() {
		return category;
	}

	public void setCategory(Category category) {
		this.category = category;
	}
}

-------------------------
@Entity
@Table(name = "categories")
public class Category implements Serializable {
	private Collection items;
...
               @OneToMany(mappedBy="category",cascade=CascadeType.ALL)
	public Collection getItems() {
		return items;
	}

	public void setItems(Collection items) {
		this.items = items;
	}
}
-----------------------------------------
in ItemAdminBean.java

@Stateless
public class ItemAdminBean implements ItemAdminInterface {
@PersistenceContext
protected EntityManager em;
...
public Collection getItemsbyCategory(String catName) {
		Category category = (Category) em.createQuery("from Category c WHERE c.name LIKE :catName").setParameter("catName",
				catName).getSingleResult();
		return category.getItems();
	}

}


when i call getItemsbyCategory in jsp page i have a problem


<% Collection items = itemAdmin.getItemsbyCategory(request.getParameter("categoryChoice"));

%>

 <%for (Iterator iter = items.iterator(); iter.hasNext();) {
	Item item = (Item) iter.next();
 
 				%>


org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: mall.entityDto.Category.items, no session or session was closed
	org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:358)
	org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:350)
	org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:343)
	org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
	org.hibernate.collection.PersistentBag.iterator(PersistentBag.java:246)
	org.apache.jsp.online_005fmall.Products_jsp._jspService(Products_jsp.java:111)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
	org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)


note The full stack trace of the root cause is available in the Apache Tomcat/5.5.17 logs.

can you help me?

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