JSF CRUD application and entities - jsf

Question

I'm writing an administration part of the application which is responsible for CRUD operations. I decided to generate the jsf pages from the jpa entities but for some reason I keep getting this error:
org.apache.jasper.el.JspELException: /busStop/List.jsp(18,12) '#{busStop.pagingInfo.itemCount == 0}' Error reading 'pagingInfo' on type jsf.BusStopController
at org.apache.jasper.el.JspValueExpression.getValue(JspValueExpression.java:107)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:416)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1607)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1613)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at com.sun.faces.application.view.JspViewHandlingStrategy.doRenderView(JspViewHandlingStrategy.java:420)
at com.sun.faces.application.view.JspViewHandlingStrategy.renderView(JspViewHandlingStrategy.java:209)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:859)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1555)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.IllegalArgumentException: The type [null] is not the expected [EntityType] for the key class [class jpa.entities.BusStop].
at org.eclipse.persistence.internal.jpa.metamodel.MetamodelImpl.entity(MetamodelImpl.java:152)
at org.eclipse.persistence.internal.jpa.querydef.AbstractQueryImpl.from(AbstractQueryImpl.java:97)
at jpa.controllers.BusStopJpaController.getBusStopCount(BusStopJpaController.java:255)
at jsf.BusStopController.getPagingInfo(BusStopController.java:43)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:62)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:54)
at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
at org.apache.el.parser.AstValue.getValue(AstValue.java:123)
at org.apache.el.parser.AstEqual.getValue(AstEqual.java:37)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
at org.apache.jasper.el.JspValueExpression.getValue(JspValueExpression.java:101)
For the moment, the whole code is generated in Netbeans 6.9, using JSF 1.2 or 2.0 and postgresql 8.4 database. Is there any solution to that problem?

Answer 1

#{busStop.pagingInfo.itemCount == 0}
Error reading 'pagingInfo' on type jsf.BusStopController
The type [null] is not the expected [EntityType] for the key class [class jpa.entities.BusStop].
Summarized: #{busStop} is null. Make sure that it's in the desired scope.

Answer 2

The workarond for DI 101 and bug #338837 to fix the IAE issue for Criteria/Metamodel users attempting to use an EntityType that is not found is to specify the location of the classes (usually not required for Java EE environments)
This environment will exist in Java SE, Spring and certain implementations of Java EE 6 Web Profile.
Exception in thread "main" java.lang.IllegalArgumentException: The type [null] is not the expected [EntityType] for the key class [class org.eclipse.persistence.example.distributed.collatz.model.UnitOfWork].
http://wiki.eclipse.org/EclipseLink/Development/JPA_2.0/metamodel_api#DI_101:_20100218:_Descriptor.javaClass_is_null_on_a_container_EM_for_a_specific_case
workaround is
http://bugs.eclipse.org/338837
<exclude-unlisted-classes>false</exclude-unlisted-classes>
or
<class>org.eclipse.persistence.example.distributed.collatz.model.UnitOfWork</class>