Problems with page and event paramters in java portlets

Question

Hi there!
Following the documentation in "A primer on Portlet Parameters and events" and "Adding Parameters an Events to Portlets" I tried to develop two portlets (who will be at the same page), one showing some content of a repository (with possibilities to browse throw it) and another showing a sitemap of the repositories whole content, presenting links to the content's pages to be shown in the content portlet.
So I added:
1. a page parameter called pageMenuID to identify the current content page to be shown in the content portlet
2. an input parameter for content portlet called portletMenuID. This input parameter is mapped to the page parameter pageMenuID
3. an event for content portlet called changeContent with output parameter contentMenuID. When this event rises, "go to page" is set to the current page and the output parameter contentMenuID is mapped to the page parameter pageMenuID.
4. an event for sitemap portlet called changeContentFromSitemap with output parameter sitemapMenuID. When this event rises, "go to page" is set to the current page and the output parameter sitemapMenuID is mapped to the page parameter pageMenuID.
This is the code for some constants and a function to build the links in the content portlet, that I want to use:
// page parameter (shouldn't be used here)
private final static String pageParamMenuID = "pageMenuID";
// parameter names as given in providers.xml:
// portlet input parameter
private final static String inputParamMenuID = "portletMenuID";
// event name
private final static String eventName = EventUtils.eventName("changeContent");
// parameter name for event parameters
private final static String eventParamMenuID = EventUtils.eventParameter("contentMenuID");
String getEventUrl( PortletRenderRequest portletRequest, long menuID) {
NameValuePair[] eventParams = new NameValuePair[2];
eventParams[0] = new NameValuePair(eventName,"");
eventParams[1] = new NameValuePair(eventParamMenuID, "" + menuID);
try {
return PortletRendererUtil.constructLink(portletRequest, portletRequest.getRenderContext().getEventURL(),
eventParams,
true,
true);
} catch (Exception e) {
return "null";
This is the analog code from the sitemap portlet:
// page parameter defined on "edit page mode" (shouldn't be used here)
private final static String pageParamMenuID = "pageMenuID";
// parameter names as given in providers.xml:
// event name
private final static String eventName = EventUtils.eventName("changeContentFromSitemap");
// parameter name for event parameters
private final static String eventParamMenuID = EventUtils.eventParameter("sitemapMenuID");
String getEventUrl( PortletRenderRequest portletRequest, long menuID) {
NameValuePair[] eventParams = new NameValuePair[2];
eventParams[0] = new NameValuePair(eventName,"");
eventParams[1] = new NameValuePair(eventParamMenuID, "" + menuID);
try {
return PortletRendererUtil.constructLink(portletRequest, portletRequest.getRenderContext().getEventURL(),
eventParams,
true,
true);
} catch (Exception e) {
return "null";
But what actually happens is nothing. I also tried to construct the links with EventUtil.constructEventLink() with the same result. Checking the produced html-code in the browser shows that the same URLs are produced. So I'm of the opinion, that proper event links are created.
After checking the sent and received request parameters I came to the conclusion, that the event output parameters are never mapped to the page input paramters, as they should. So I changed the code to the following:
// page parameter (shouldn't be used here)
private final static String pageParamMenuID = "pageMenuID";
// parameter names as given in providers.xml:
// event name
private final static String eventName = EventUtils.eventName("changeContentFromSitemap");
// parameter name for event parameters
private final static String eventParamMenuID = EventUtils.eventParameter("sitemapMenuID");
String getEventUrl( PortletRenderRequest portletRequest, long menuID) {
NameValuePair[] eventParams = new NameValuePair[1];
eventParams[1] = new NameValuePair(pageParamMenuID, "" + menuID); <-- Note that the page parameter and not the event output parameter is used here -->
try {
return PortletRendererUtil.constructLink(portletRequest, portletRequest.getRenderContext().getEventURL(),
eventParams,
true,
true);
} catch (Exception e) {
return "null";
Now everything works fine, including addition of persistent private portlet parameters and further input/page/event parameters as well as working with a third portlet with performs a search (and presents the search results as links which change the content in content portlet).
But this is actually NOT the way it should work: The names of the page parameters are hard-coded in the portlets, so the roles of page designer and portlet developer are not separated in the way it is presented in the documentation. I coulnd't find a way to map the event output parameters to the page parameters to work this out.
Now I wonder whether there's some known bug in PDK or perhaps a mistake in the documentation or wether I'm just missing doing the right things. I've already read some postings in this forum concerning this problem (for example how to change the query??? but I think I've done all the things that are suggested there (checked the entries in provider.xml and the proper mapping of page parameters, public (input) portlet parameters and event output parameters, also the way I read the received request parameters and build the links)
Has anybody an idea what's wrong here?
Best regards
Torsten

Answer 1

Hi Amjad,
thank you very much for time and effort you spent on helping me solving this problem.
Unfortunately, I think I already tried what you suggest in your answer, but without success. From my experience, the following two calls:
1.
<%!
private static String eventName = "changeContent"
private static String eventParamID = "menuID"
String getEventUrl(PortalRenderRequest prr, long menuID) {
NameValuePair[] eventParams = new NameValuePair[1];
// no addition of eventName in the array
eventParams[0] = new NameValuePair(eventParamID, "" + menuID);
return EventUtils.constructEventLink(prr, eventName, eventParams, true, true);
%>
<a href="<%= getEventUrl(portletRequest, 1234) %>">some link for ID 1234</a>
2.
<%!
private static String eventName = EventUtils.eventName("changeContent");
private static String eventParamID = EventUtils.eventParameter("menuID");
String getEventUrl(PortalRenderRequest prr, long menuID) {
NameValuePair[] eventParams = new NameValuePair[2];
eventParams[0] = new NameValuePair(eventParamID, "" + menuID);
eventParams[0] = new NameValuePair(eventName,"");
return PortletRendererUtil.constructLink(prr, prr.getRenderContext().getEventURL(), eventParams, true, true);
%>
<a href="<%= getEventUrl(portletRequest, 1234) %>">some link for ID 1234</a>
produce identical links. I took the second way because it is easer to add private portlet parameters to the link: just as additional NameValuePairs in the eventParam- Array (name constructed with HttpPortletRendererUtil.portletParameter()), instead of constructing the link "by hand" as mentioned in the javadoc for constructEventLink(). I have to add these private portlet parameters here because when an event from a private parameters owning portlet is fired, the private parameters are lost (in difference to when an event from ANOTHER portlet is sent).
So I think, when you also look closely to the code snippet I added in the first posting, I made shure that I added the name of the event and not just the event parameters to the link.
I hope that I understood your answer right. Perhaps you have another idea what might be wrong. Thank you again,
best regards
Torsten