Another conversation question ...

[greko]

Hi all !

I have a screen displaying a list of devices. A device can be edited (from a button in the datatable)
When a submit a find on my deviceList screen, I start a new conversation.
When I edit a device, a create a nested conversation : once on my edit screen, I want to be able to go back to my previous search (aka the parent conversation).

The problem :
When a perform a save, on my edit screen, everything seems ok (faces message ok, entity updated). But then, when I click on my cancel/back button, to go back to my list, it is empty ... I mean, everything is still in the conversation (my search panel, even the rowCount of the list) but the list contains null elements ...

Here is part of my code :

pages.xml

...
 <page view-id="/parc_deviceList.xhtml" no-conversation-view-id="/parc_deviceList.xhtml">
 <description>Device Search (Results: #{deviceSearch.rowCount})</description>
 </page>
...
 <page view-id="/parc_deviceEdit.xhtml">
 <description>Edit Device</description>
 <param name="deviceId" value="#{deviceHome.deviceId}"/>
 <action execute="#{deviceHome.init}"/>
 <begin-conversation flush-mode="MANUAL" join="true"/>
 <navigation>
 <rule if-outcome="updated">
 <redirect view-id="/parc_deviceEdit.xhtml">
 </redirect>
 </rule>
 </navigation>
 </page>
...

parc_deviceList.xhtml

...
 <h:commandLink id="find" styleClass="button"
 action="#{deviceSearch.find()}"
 tabindex="6">
 <s:conversationPropagation type="join" />
 <h:outputText styleClass="buttonLabel" value="#{messages['findButton']}"/>
 </h:commandLink>
...
 <h:dataTable id="deviceTable" var="d"
 value="#{devicesList}"
...
 <h:column>
 <f:facet name="header"> </f:facet>

 <s:link view="/parc_deviceEdit.xhtml" propagation="nest" title="#{messages['device.edit']}">
 <h:graphicImage value="/img/bt_mini_edit.gif" style="border:0; padding:2px;" />
 <f:param name="deviceId" value="#{d.id}"/>
 </s:link>
 </h:column>
...

parc_deviceEdit.xhtml

 <h:form id="deviceEditForm">
 <div class="formFields wideLabels formBorder">
 <s:validateAll>
...
 </s:validateAll>
 </div>

 <div class="formControls wideLabels">
 <div class="entry">
 <div class="label"> </div>
 <div class="input">
 <h:commandLink id="update" styleClass="button"
 action="#{deviceHome.update}"
 tabindex="9">
 <span class="buttonLabel">#{messages['saveButton']}</span>
 </h:commandLink>

 <s:link id="cancel" styleClass="button" view="/parc_deviceList.xhtml"
 tabindex="9">
 <span class="buttonLabel">#{messages['cancelButton']}</span>
 </s:link>
 </div>
 </div>
 </div>

DeviceHome.java

@Name("deviceHome")
@Scope(ScopeType.CONVERSATION)
public class DeviceHome extends EntityHome<RTHDevice> {

 @Logger
 private Log logger;


 public Long getDeviceId() {
 return (Long)getId();
 }

 public void setDeviceId(Long deviceId) {
 setId(deviceId);
 }

 public void init() {
 logger.debug("DeviceHome.init()");

 if (isManaged()) {
 } else {
 }
 }

 public String persist() {
 logger.debug("DeviceHome.persist()");
 getInstance().setActive(0);

 return super.persist();
 }

 public String update() {
 logger.debug("DeviceHome.update()");
 return super.update();
 }
}

DeviceSearchAction.java

@Stateful
@Scope(ScopeType.CONVERSATION)
@Name("deviceSearch")
@Restrict("#{identity.loggedIn}")
public class DeviceSearchAction implements DeviceSearch, Serializable {
...
 @DataModel
 List<RTHDevice> devicesList;
...

I can't figure out why this happens.
Could you help me a few ?

I'm currently using seam 2.0.0.CR1 on JBoss 4.2.1.GA.

Thanks for your help !

[pmuir]

You've outjected a variable into conversation scope and as you are in the same conversation the original value is still there and not recreated.

Try using an afterTransactionSuccess event as documented here http://docs.jboss.org/seam/2.0.0.CR3/reference/en/html/framework.html#d0e6304

[greko]

Hi Pete !

Thanks for your reply.

I've updated my code so that I always stay in the same conversation (no more nested).

I've also added this :

DeviceSearchAction.java

 @Observer("org.jboss.seam.afterTransactionSuccess.RTHDevice")
 public void refreshDevices() {
 logger.debug("refreshDevices() method called.");
 queryDevices();
 }

But I still have a problem : If I perform a submit on my edit screen, and the validation fails, my data is gone and not recreated. So if I click my cancel button, whithout finishing my transaction, I return to my previous list with empty data.
Is there another event to observe ? Or should I refresh my data each time I return to my list ?

Thanks a lot !

[pmuir]

Given your app design, this would seem sensible.

[greko]

That is what I thought.

But what would be the best app design, given such a simple scenario ?
I could use a session context, but my data will remain in the session, whereas a conversation will be automatically timeout-ed ...

Am I right, or is my approch wrong ?

[pmuir]

You should decide what scope makes sense for your application and make Seam do the right thing, not the other way around ;)

Session scope makes sense if you want the same result list to be displayed without the user hitting Search again whilst they are logged in. A nested conversation makes sense if you want to hold the list in a conversation and atomically edit entities.

[greko]

I agree with you Pete !
And actually, that's what I am trying to do.

I want my search->edit->back-to-search lifecycle to be managed with conversations.

I'm working on it, and the main problem is still the same : how to return to my parent conversation (the result list) without loosing data ...?