Nested conversation
Hello Seam users.
I know that this kind of problem has been submitted many times in many different flavors but I can't determine the cause of my problem.
Here is a description of it.
I Have an application which consists mainly of 2 pages. The first is a list of items and the second is an editor page for an item in the list.
When I enter the first page, I start a Conversation (@Begin) on a stateful bean with Conversation scope. I need this conversation because my list must keep track of different states as sort order, sort field, page selected etc.
When I click on an item to edit it, I switch to the second page starting a nested conversation. I can then take action on the item and return to the list that I find in the state I left it. My problem starts here. The list is correctly rendered but when I do an action on it, I get an exception (NullPointerException) on the first property of the backing bean that I access.
I put the conversationList dataTable on my pages to track the conversations and everything seems fine. On the first page, I have 1 conversation. On the second, I have 2 with the second as current and it is nested. When I come back to my list page, I have only one conversation left and it is exactly the same as when I started (same ID, accessedDate refreshed).
So, here are the relevant portions of code:
The method that starts the conversation on the list backing bean
@Begin
@Override
@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
public String enterList() {
this.currentKilometerEntryMonth = null;
this.com_servier_hr_session_uievents_kilometerEntryMonths = null;
queryObjects();
this.carPanelRendered = false;
return "kilometerEntryMonthList";
}kilometerEntryMonthList is the logical name of the list page as defined in
pages :
<page view-id="/kilometerEntry/kilometerEntryMonthList.xhtml"
login-required="true">
<description>The month list page of the application</description>
<navigation>
<rule if-outcome="carList">
<redirect
view-id="/kilometerEntry/#{com_servier_hr_session_uievents_carListAction.enterList()}.xhtml">
</redirect>
</rule>
</navigation>
</page>The link to the second page :
<a4j:commandLink id="monthListYearMonthColumnLink"
action="#{com_servier_hr_session_uievents_kilometersEdit.enterEdit(kilometerEntryMonthDTO)}">
<h:outputText value="#{kilometerEntryMonthDTO.yearMonth}"
id="monthListYearMonthColumnOutputText" />
<f:param name="conversationPropagation" value="join" />
<s:conversationPropagation type="join" />
</a4j:commandLink>The method enterEdit on the backing bean of the second page :
@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
@Begin(nested = true)
public String enterEdit(KilometerEntryMonthDTO kilometerEntryMonthDTO) {
this.ownerServierUser = null;
this.setPreviousKilometerEntry(null);
this.nextKilometerEntry = null;
this.setCurrentKilometerEntry(null);
this.currentKilometerEntryMonth = null;
this.com_servier_hr_session_uievents_car = null;
createNeededServices();
---The link on the second page to return to the first :
<rich:menuItem submitMode="ajax" id="goBackToListMenuItem"
value="#{messages['KilometerEntry.cmdBack.tooltip']}"
action="#{com_servier_hr_session_uievents_kilometersEdit.returnToMonthList()}"
eventsQueue="treeQueue" bypassUpdates="true" immediate="true"
<f:facet name="icon">
<h:graphicImage value="/img/actions/back.gif"
id="goBackToListImage" />
</f:facet>
</rich:menuItem>The method on the backing bean of the second page that ends the nested conversation :
@End()
@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
public String returnToMonthList() {
return "kilometerEntryMonthList";
}The entry for that second page in pages.xml :
<page view-id="/kilometerEntry/kilometerEntryList.xhtml"
login-required="false">
<description>The edition of the monthly entries</description>
<navigation>
<rule if-outcome="kilometerEntryMonthList">
<redirect
view-id="/kilometerEntry/#{com_servier_hr_session_uievents_KilometerEntryMonthSearch.returnToList()}.xhtml">
</redirect>
</rule>
</navigation>
</page>
And finally, the method on the backing bean of the list page that the previous navigation rule refers to :
@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
public String returnToList(){
queryObjects();
if(this.sortField!=null){
this.sortAscending = !this.sortAscending;
this.sortDataList(this.sortField);
}
return "kilometerEntryMonthList";
}Voila, if someone sees something that I don't, it would be highly appreciated.
Vincent.
