DataModel using Set does not work

[andreigh.ts]

Hi,

I am trying to use java.util.Set as a @DataModel but it throws an exception (javax.faces.el.PropertyNotFoundException .... Bean: org.hibernate.collection.PersistentSet) when trying to display the xhtml.

Replacing Set with List or array works very well.

Here is the code:

The Hibernate Entity bean that initially holds the set:

@Entity
@Table(name = "RFQ_Request", uniqueConstraints = {})
public class RfqRequest implements java.io.Serializable {
...
 private Set<RfqRequestQuestion> rfqRequestQuestions = new HashSet<RfqRequestQuestion>(0);
...
}

One element of the Set looks like this:

@Entity
@Table(name = "RFQ_Question", uniqueConstraints = {})
public class RfqQuestion implements java.io.Serializable {
...
 @Column(name = "Description", unique = false, nullable = false, insertable = true, updatable = true)
 public String getDescription() {
 return this.description;
 }
...
}

A seam component that should expose the DataModel:

@Stateless
@Name("requestWizardQuestions")
public class RequestWizardQuestionsAction implements RequestWizardQuestions {
 @In(required=false, scope=ScopeType.CONVERSATION)
 @Out(required=false, scope=ScopeType.CONVERSATION)
 private RfqRequest rfqRequest;

 @DataModel
 public Set<RfqRequestQuestion> getRfqQuestions() {
 return rfqRequest.getRfqRequestQuestions();
 }

 @DataModelSelection
 private RfqRequestQuestion selectedQuestion;
}

And the page that should display the DataModel:

...
<h:dataTable var="question" value="#{requestWizardQuestions.rfqQuestions}" >
 <h:column>
 <f:facet name="header">
 <h:outputText value="Question"/>
 </f:facet>
 <h:outputText value="#{question.description}"/>
 </h:column>
 </h:dataTable>
...

This throws this exception when trying to display the page:

javax.faces.el.PropertyNotFoundException: /requestWizard/questions.xhtml @24,59
value="#{question.description}": Bean: org.hibernate.collection.PersistentSet, property: description
 at com.sun.facelets.el.LegacyValueBinding.getValue(LegacyValueBinding.java:58)
 at javax.faces.component.UIOutput.getValue(UIOutput.java:77)
.......

If I change the @DataModel and replace the Set < RfqQuestion > with RfqQuestion[]. it works.
What is wrong?

Thanks

[andreigh.ts]

Is there an example of how to use Set as a @DataModel ?

[pmuir]

It should be

<h:dataTable var="question" value="#{rfqQuestions}" >
</h:dataTable>
...

- you want to bind to the outjected variable, not the property of the bean.

[andreigh.ts]

Thanks, it works. Now I understand, @DataModel outjects a brand new object with a new name (default variable name). This also means that the variable should be created with @Factory (usually).

Now I don't understand why my initial approach worked with List and array :)

[pmuir]

Because JSF supports sets and arrays natively, but not Sets - Seam does some trickery there.

[andreigh.ts]

There is something weird how this @DataModel functions, maybe it can be documented somewhere.

In my example the @DataModel exposes the Set of a hibernate entity(from one-many relationship).

If the @DataModel is a property of a stateful bean (conversation scope), then modifying the hibernate set, automatically updates the DataModel (this means that somehow seam links the DataModel to the original object; it does not clone the collection?)

But if @DataModel is a property of a stateless bean, then modifying the hibernate set has no effect in the user interface.

I'm confused ... it's a bug?

[gavin.king]

Its to do with the default scoping rules. In the case of a SLSB, the datamodel defaults to PAGE context, which means gets serialized back and forth to the client.

[andreigh.ts]

Thank you all for the answers.

Can you please help me out - There still are some problems and searching on the forum seemsto be bugs, but I am not sure. Can you please confirm.

Here are the problems:

1) Stateful component - Conversation scope; outjecting Set DataModel (defaulting to Conversation scope).
Problem - UI is not refreshed, even though the Factory method is called on the add event.

@Stateful
@Scope(ScopeType.CONVERSATION)
@Name("requestWizardQuestions")
public class RequestWizardQuestionsAction implements RequestWizardQuestions {
...
 @DataModel
 public Set<RfqRequestQuestion> requestQuestionsList;

 @DataModelSelection
 @Out(required=false)
 private RfqRequestQuestion selectedQuestion;

 @Factory("requestQuestionsList")
 public void initQuestionsList() {
 requestQuestionsList = rfqRequest.getRfqRequestQuestions());
 }

 public void addNewQuestion() {
 rfqRequest.getRfqRequestQuestions().add(new RfqRequestQuestion());
 initQuestionsList();
 }
...
}

Replacing Set with List works.
Is this a bug signaled here: http://www.jboss.com/index.html?module=bb&op=viewtopic&t=106232
?

2) Stateful component - Conversation scope; outjecting DataModel to PAGE scope.
Problem - The @DataModelSelection is null (seems not to be injected) after clicking the item in UI.

@Stateful
@Scope(ScopeType.CONVERSATION)
@Name("requestWizardQuestions")
public class RequestWizardQuestionsAction implements RequestWizardQuestions {
...
 @DataModel(scope=ScopeType.PAGE)
 public List<RfqRequestQuestion> requestQuestionsList;

 @DataModelSelection
 @Out(required=false)
 private RfqRequestQuestion selectedQuestion;

 @Factory("requestQuestionsList")
 public void initQuestionsList() {
 requestQuestionsList = new ArrayList<RfqRequestQuestion>(rfqRequest.getRfqRequestQuestions());
 }

 public void deleteQuestion() {
 rfqRequest.getRfqRequestQuestions().remove(selectedQuestion); entityManager.remove(selectedQuestion);
 }

...
}

deleteQuestion is called when clicking an item in the List, but selectedQuestion is null.

Is this the bug posted here:
http://jira.jboss.com/jira/browse/JBSEAM-308
?

Am I doing something wrong, or are just 2 bugs?

Thanks