4 Replies Latest reply on Jun 26, 2008 12:25 PM by morphi

LinkedList as @DataModel- ClassCastException

morphi Jun 25, 2008 1:16 PM

Hi,
I have a small problem with using @DataModel.

Here is my code:
web page:

<rich:dataTable sortMode="multi" id="tableId"                         
       width="100%" rows="10" value="#{dane}" var="row">
 <rich:column sortBy="#{row.value1}">
   <f:facet name="header">
        <h:outputText styleClass="headerText" value="First Name" />
   </f:facet>
   <h:outputText value="#{row.value1}"/>
 </rich:column>
 ...
</rich:dataTable>

Java:

@Stateless
@Scope(ScopeType.SESSION)
@Name("testData")
public class TestData implements TestDataLocal {
    @DataModel
    @Out(required=false)
    private List<SampleDataDTO> dane;
   
    
    @Factory("dane")
    public void pupulateDane(){
        dane = new LinkedList<SampleDataDTO>();
        dane.add(new SampleDataDTO("1","2","3"));
    }
    ...
}

@Local
public interface TestDataLocal {  
   ...
   public void pupulateDane();
   ...
}

DTO:

public class SampleDataDTO {
        private String value1;
        private String value2;
        private String value3;
        
        public SampleDataDTO(String value1, String value2, String value3){
                this.value1 = value1;
                this.value2 = value2;
                this.value3 = value3;
        }

        public String getValue1() {
                return value1;
        }

        public void setValue1(String value1) {
                this.value1 = value1;
        }

        public String getValue2() {
                return value2;
        }

        public void setValue2(String value2) {
                this.value2 = value2;
        }

        public String getValue3() {
                return value3;
        }

        public void setValue3(String value3) {
                this.value3 = value3;
        }
}

When I enter the page I get an ClassCastException.

...
Caused by: java.lang.ClassCastException: java.util.LinkedList
        at org.jboss.seam.databinding.DataModelBinder.isDirty(DataModelBinder.java:14)
        at org.jboss.seam.Component.outjectDataModel(Component.java:1537)
        at org.jboss.seam.Component.outjectDataModels(Component.java:1522)
        at org.jboss.seam.Component.outject(Component.java:1474)
        at org.jboss.seam.core.BijectionInterceptor.aroundInvoke(BijectionInterceptor.java:47)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.core.MethodContextInterceptor.aroundInvoke(MethodContextInterceptor.java:42)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.persistence.EntityManagerProxyInterceptor.aroundInvoke(EntityManagerProxyInterceptor.java:26)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.persistence.HibernateSessionProxyInterceptor.aroundInvoke(HibernateSessionProxyInterceptor.java:27)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:107)
        at org.jboss.seam.intercept.SessionBeanInterceptor.aroundInvoke(SessionBeanInterceptor.java:50)
        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:585)
        at org.jboss.ejb3.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:118)
        at org.jboss.ejb3.interceptor.EJB3InterceptorsInterceptor.invoke(EJB3InterceptorsInterceptor.java:63)
        at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
        at org.jboss.ejb3.entity.TransactionScopedEntityManagerInterceptor.invoke(TransactionScopedEntityManagerInterceptor.java:54)
        at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
        at org.jboss.ejb3.AllowedOperationsInterceptor.invoke(AllowedOperationsInterceptor.java:47)
        at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
        at org.jboss.aspects.tx.TxPolicy.invokeInCallerTx(TxPolicy.java:126)
        ... 118 more

In all examples I have seen factory method used .getResultList() from Query. Why can't I use LinkedList?
Is it possible to have a List as a DataModel but not containing Entity Beans ?

1. Re: LinkedList as @DataModel- ClassCastException

graben Jun 25, 2008 2:07 PM (in response to morphi)

Did you try not to use @DataModel and @Out. I think that should solve your problem!
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2. Re: LinkedList as @DataModel- ClassCastException

morphi Jun 25, 2008 11:53 PM (in response to morphi)

It works if I change the code like that:

@Stateless
@Scope(ScopeType.SESSION)
@Name("testData")
public class TestData implements TestDataLocal {

    private List<SampleDataDTO> dane;
   
    
    @Factory("dane")
    public List<SampleDataDTO> pupulateDane(){
        dane = new LinkedList<SampleDataDTO>();
        dane.add(new SampleDataDTO("1","2","3"));
        return dane;
    }
    ...
}

But I think it does not solve my problem.
I also want to use @DataModelSelection. Correct me if I am wrong but I need @DataModel for that.

3. Re: LinkedList as @DataModel- ClassCastException

obfuscator Jun 26, 2008 11:38 AM (in response to morphi)
When you have both @DataModel and @Out, they will both outject your list into the context under the name dane. The @DataModel outjection will wrap your list in a ListDataModel. The @Out will simply outject the list as-is. The exception your are getting is when these two objects get mixed up (trying to cast the ListDataModel to List or the other way around).

If you want to outject a variable both as a @DataModel and @Out, you have to give them different names, something like

@DataModel("daneModel") @Out("dane") private List<SampleDataDTO> dane;

This way, there will be no confusion about the type of the context variables.
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4. Re: LinkedList as @DataModel- ClassCastException

morphi Jun 26, 2008 12:25 PM (in response to morphi)

I wrote that based on example from Core JavaSercer Faces book.
(It seems like I should have look into seam examples where @DataModel is used without @Out annotation.)
It works without @Out.
Thank you for your explanation!
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