Creation of breadcrumb links in FlowExecutionListener

[kajism]

Hi,

I would like to generate a breadcrumb navigation bar showing active flows and subflows. I want to display this on all pages (view states).

FlowExecutionListener seems to be a good place for this, but I need to have 2 pieces of information: flowExecutionId (used for the generated anchors) which is accessible only in saved() method and also requestScope where I want to place the generated navigation to be accessible for the pages, but I cannot find a way how to access the requestScope in saved() of FlowExecutionListener.

RequestScope is easily reachable in stateEntered() but here I don't have access to the flowExecutionId (doesn't exist yet) which will be used in views.

Is there a way how to do this or a new callback method should be added to the FlowExecutionListener which would be called just before the control si passed to a view and its parameters would contain requestContext (which would already contain the flowExecutionId at the moment).

Thanks,
Karel

[Colin Yates]

would

public void requestSubmitted(RequestContext context);

not be better, or event

public void requestProcessed(RequestContext context);

[kajism]

Unfortunatelly not. requestSubmitted() is called too soon (before state transition and new flowExecutionId creation) and requestProcessed() seems to be called too late (after the view has been rendered)

[Keith Donald]

You could override FlowExecutionManager prepareViewDescriptor.

We might want to add a FlowExecutionListener.viewReturning callback, given you access to put stuff in the selected and prepared ViewDescriptor, where you could put whatever you wanted in the model Map.

[Colin Yates]

kajism.

My bad

[kajism]

Thanks for your help guys.

Keith, the FlowExecutionListener.viewReturning() callback would be definitely usefull.
In addition, please, the addSubflowState() methods of AbstractFlowBuilder should probably return the created SubflowState (as usual for the other addXXX methods in the builder) instead of void.

Thanks a lot,
Karel

[klr8]

You could also just do it with a custom JSP tag in the JSP itself. Remember that except for the "flowExecutionId" and "currentStateId", also the FlowExecutionContext" is available to the view using the "flowExecutionContext" attribute. The FlowExecutionContext gives you access to all information you need to generate a breadcrumbs kind of thing (e.g. getFlowSession(), getFlowSession().getParent(), getFlowSession().getCurrentState(), ...) and ofcourse you already have the flow execution id.

Erwin

[akw]

Thought it might be worth sharing my implementation of a breadcrumb trail based on flow hierarchy. This FlowExecutionListenerAdapter builds a List of strings (one per crumb) and places it into the request context under the key "breadcrumbs".

Note that flow names don't always provide the most meaningful breadcrumb text. I'm using a MessageSource to lookup localized breadcrumb strings.

A flow can be omitted from the breadcrumb trail by assigning it an empty name in the message source.

public class BreadcrumbFlowExecutionListener extends FlowExecutionListenerAdapter {

    protected MessageSource messageSource;

    public void setMessageSource(MessageSource messageSource) {
        this.messageSource = messageSource;
    }

    public void stateEntering(RequestContext ctx, State state) throws EnterStateVetoException {
        if (state instanceof ViewState) {
            FlowSession session = ctx.getFlowExecutionContext().getActiveSession();
            List crumbs = new ArrayList();
            Map scopeMap = session.getScope().getAttributeMap();
            crumbs.add(getLocalizedFlowName(scopeMap, session.getFlow().getId()));
            while (session.getParent() != null) {
                session = session.getParent();
                scopeMap = session.getScope().getAttributeMap();
                String flowName = getLocalizedFlowName(scopeMap, session.getFlow().getId());
                if (flowName != null && !flowName.equals(""))
                    crumbs.add(0, flowName);
            }
            ctx.getRequestScope().setAttribute("breadcrumbs", crumbs);
        }
    }

    public String getLocalizedFlowName(Map attributeMap, String flowId) {
        return attributeMap, messageSource.getMessage(flowId, new String[0], flowId, Locale.getDefault());
    }
}

[viswa]

Hi,

I am in a need to implemnt breadcrumb in my project. we are using springframework1.2.8. I knew that for implementing breadcrumb we need to have FlowExecutionListenerAdapter class for which webflow-support.jar which is not present in spring1.2.

Is it still possible to do breadcrumb with spring1.2.8. Kindly help me and tell me the procedure to do that

[klr8]

The FlowExecutionListenerAdapter is part of Spring Web Flow (SWF), which is a subproject of Spring proper. This thread describes how to do breadcrumbs in SWF.

Check http://www.springframework.org/webflow for details.

Erwin