Polimorphism problem
** Problem: I cannot customize content of a template, depending on a type of
returned hibernate @Entity.
** Environment: MyFaces 1.1.4, Facelets 1.1.12, Seam 1.1.6, Hibernate 3.2.1.
** Situation:
I have three Hibernate entities:
1. Item - annotated with @Inheritance(strategy=InheritanceType.SINGLE_TABLE),
@DiscriminatorColumn, @DiscriminatorValue, @Entity
public void getProperty();
isExtendedFlagSet(); //returning true only when this is instance of
//ExtendedItem below (I need such flags in
//general)
2. ExtendedItem extends Item - annotated with @DiscriminatorValue, @Entity
public void getExtendedProperty();
3. ItemHolder - annotated with @Entity
Item getItem();
And an EVENT scope backer:
currentItemProvider getting ItemHolder proxies/instances from Hibernate.
And two jsf+facelets templates, which I want to render different in case when
ItemHolder.getItem()
returns instance if ExtendedItem than when it returns instance of Item.
** My (not working completely) solution:
Using custom, render-time-if component, which renders children when
"currentItemProvider.itemholder.item.extendedFlagSet" is true,
enable fragment of page:
<h:outputText value="#{currentItemProvider.itemholder.item.property}"/>
<mycomp:renderTimeIf
condition="#{currentItemProvider.itemholder.item.extendedFlagSet}">
<h:outputText
value="#{currentItemProvider.itemholder.item.extendedProperty}"/>
</mycomp:renderTimeIf>
1. WORKS OK, when placed in a render-time loop of ui:repeat. Different item
appear
on a page rendered according to their isExtendedFlagSet value
2. But DOESN'T work when put in compile-time ui:decorate or direct in a
template. I get:
SEVERE: Error Rendering View[/itemDetails.xhtml]
javax.faces.el.PropertyNotFoundException: /WEB-INF/templates/itemtemplate.xhtml
@18,132 value="#{currentItemProvider.itemholder.item.extendedProperty}":
Bean: package.Item$$EnhancerByCGLIB$$b215fa4e, property: extendedProperty
at
com.sun.facelets.el.LegacyValueBinding.getValue(LegacyValueBinding.java:58)
at javax.faces.component.UIOutput.getValue(UIOutput.java:77)
at
org.apache.myfaces.shared_impl.renderkit.RendererUtils.getStringValue(RendererUtils.java:217)
at
org.apache.myfaces.shared_impl.renderkit.html.HtmlTextRendererBase.renderOutput(HtmlTextRendererBase.java:69)
at
org.apache.myfaces.shared_impl.renderkit.html.HtmlTextRendererBase.encodeEnd(HtmlTextRendererBase.java:57)
at
javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:536)
** Question: how to deal with such instance-dependent customization? I have a
huge, complex domain (above is only a simplified illustration)
and would gladly stay with this consistent isFlasSet() approach, but if it
should be done in a different way, please suggest.
Regards,
Przemek
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