Breadcrumbs within the same conversation / pageflow

[ngeadah]

Hi All,

I noticed that Seam has some rudimentary support for breadcrumbs, as outlined in the following section of the documentation:

http://docs.jboss.com/seam/latest/reference/en/html/conversations.html#d0e3244

This is fine for nested-conversations, but does not solve the more common case of displaying the sequence of pages traveled by the user within the SAME conversation (defined using a pageflow, for example). Is there any support built-in to get the list of pages traveled within the conversation? If not, any suggestions on how to achieve this? Probably a servlet filter that keeps track of navigation but handling the back button might be a pain...

Thanks

[gavin.king]

A page action mapped to "*" is a better choice than a servlet filter.

[ngeadah]

Thanks Gavin.

I will assume from your answer that breadcrumb creation in this way is not a built-in Seam component. Is this being considered as a roadmap item for the future? IMHO, breadcrumbs are more prevalent within a single conversation as opposed to the breadcrumb support from Seam which accomodates for nested conversation. The latter is nice, but the former seems (seams ;) more important.

Thanks again!

[ngeadah]

Here is the solution. This creates a clickable breadcrumb trail as the user moves through the pageflow. The breadcrumb trail gets correctly adjusted if the user goes back.

1- A page action mapped to "*" in pages.xml

<pages>

 <page view-id="*" action="#{breadcrumb.log}"/>

</pages>

2- A "breadcrumb" Seam component:

@Name("breadcrumb")
public class BreadcrumbHandler {
 private List<Page> conversationCrumb;

 public void log() {
 try {
 if (Contexts.isConversationContextActive()) {
 conversationCrumb = (List) Contexts.lookupInStatefulContexts("conversationCrumb");
 if (null == conversationCrumb) conversationCrumb = new LinkedList<Page>();
 if (null != Pageflow.instance()) {
 if (null != Pageflow.instance().getPage()) {
 Page thePage = Pageflow.instance().getPage();
 if (conversationCrumb.contains(thePage)) {
 // rewind the conversation crumb to where the page is
 conversationCrumb = conversationCrumb.subList(0, conversationCrumb.indexOf(thePage)+1);
 } else {
 conversationCrumb.add(thePage);
 }
 }
 Contexts.getConversationContext().set("conversationCrumb",conversationCrumb);
 }
 } else {
 Contexts.removeFromAllContexts("conversationCrumb");
 }
 } catch (Throwable t) {
 // Do nothing as this is just a "listener" for breadcrumbs
 t.printStackTrace();
 }
 }

 public void navigate()
 {

 FacesContext context = FacesContext.getCurrentInstance();
 Map map = context.getExternalContext().getRequestParameterMap();
 String viewId = (String) map.get("viewId");
 String pageName = (String) map.get("name");

 Pageflow.instance().reposition(pageName);

 Redirect redirect = Redirect.instance();
 redirect.setViewId(viewId);
 redirect.execute();

 }
}

3- JSF tags needed to display the crumbs. This relies on the h:commandLink which creates Javascript, but it's probably pretty easy to change this to an s:link instead (although s:link won't take paramaters until the Seam 1.1 release). Also, I wish I could print out the page description instead of the page name, but Seam has a bug when calling getDescription on a page (http://jira.jboss.com/jira/browse/JBSEAM-272)

 <t:dataList value="#{conversationCrumb}" var="crumb">
 <h:outputText value=" | "/>
 <h:commandLink action="#{breadcrumb.navigate}">
 <f:param name="viewId" value="#{crumb.viewId}"/>
 <f:param name="name" value="#{crumb.name}"/>
 <h:outputText value="#{crumb.name}"/>
 </h:commandLink>
 </t:dataList>

[gavin.king]

Why not post this "pattern" to the wiki?

[jpviragine]

Hi ngeadah,

I?m using your code with current cvs version and jbpm-3.1.2.jar.
The getDescription works fine.

Regards,

Joao Paulo

[amit.rakhaiya]

conversationCrumb = (List) Contexts.lookupInStatefulContexts("conversationCrumb");

Can you please tell me what is "conversationCrumb" ??