It is quite common to display a message to the user indicating success or failure of an action. It is convenient to use a JSF FacesMessage for this. Unfortunately, a successful action often requires a browser redirect, and JSF does not propagate faces messages across redirects. This makes it quite difficult to display success messages in plain JSF.
The built in conversation-scoped Seam component named facesMessages solves this problem. (You must have the Seam redirect filter installed.)
@Name("editDocumentAction")
@Stateless
public class EditDocumentBean implements EditDocument {
@In EntityManager em;
@In Document document;
@In FacesMessages facesMessages;
public String update() {
em.merge(document);
facesMessages.add("Document updated");
}
}
Any message added to facesMessages is used in the very next render response phase for the current conversation. This even works when there is no long-running conversation since Seam preserves even temporary conversation contexts across redirects.
You can even include JSF EL expressions in a faces message summary:
facesMessages.add("Document #{document.title} was updated");
You may display the messages in the usual way, for example:
<h:messages globalOnly="true"/>
