Class Cast Exception on WebSession

[Brad Gardner <bg...@gmail.com>]

I'm brand new to wicket and going through the book "Wicket in Action".  I've
ran into a problem that I can't seem to get around, maybe I am over thinking
it.  I have a class I wrote that extends
org.apache.protocol.http.WebSession, and I am getting a ClassCastException
when I try to return my session.  This is the cheese store example from the
book if anyone is familiar with it.  Here is the code in question:

*From my class that extends WebPage:
*
public CheeseStoreSession getCheeseStoreSession()
    {
        return (CheeseStoreSession) getSession(); *//exception occurs right
here*
    }

I've confirmed that the getSession method is returning an object of type
WebSession.
*
My custom session class looks like this:*


package com.manning.example;

import org.apache.wicket.Request;
import org.apache.wicket.Response;
import org.apache.wicket.Session;
import org.apache.wicket.protocol.http.WebSession;


public class CheeseStoreSession extends WebSession
{
    private Cart cart = new Cart();


    protected CheeseStoreSession(Request request)
    {
        super(request);
    }


    public Cart getCart()
    {
        return cart;
    }


    public Session newSession(Request request, Response response)
    {
        return new CheeseStoreSession(request);
    }
}



I am having difficulty understanding the purpose of the ClassCastException
that I am getting.  Here is the exception:

WicketMessage: Error calling method: public com.manning.example.Cart
com.manning.example.CheeseStorePage.getCart() on object: [Page class =
com.manning.example.Index, id = 13, version = 0]

Root cause:

java.lang.ClassCastException: org.apache.wicket.protocol.http.WebSession
at
com.manning.example.CheeseStorePage.getCheesrSession(CheeseStorePage.java:27)
at com.manning.example.CheeseStorePage.getCart(CheeseStorePage.java:33)
at java.lang.reflect.Method.invoke(Method.java:585)
at
org.apache.wicket.util.lang.PropertyResolver$MethodGetAndSet.getValue(PropertyResolver.java:1046)
at
org.apache.wicket.util.lang.PropertyResolver.getObjectAndGetSetter(PropertyResolver.java:242)
at
org.apache.wicket.util.lang.PropertyResolver.getValue(PropertyResolver.java:87)
at
org.apache.wicket.model.AbstractPropertyModel.getObject(AbstractPropertyModel.java:113)
at org.apache.wicket.Component.getModelObject(Component.java:1559)
at
org.apache.wicket.markup.html.list.ListView.getViewSize(ListView.java:217)
at org.apache.wicket.markup.html.list.ListView.onPopulate(ListView.java:524)
at
org.apache.wicket.markup.repeater.AbstractRepeater.onBeforeRender(AbstractRepeater.java:127)
at org.apache.wicket.Component.internalBeforeRender(Component.java:1003)

...

...


Can someone point me in the right direction for diagnosing this?

-- 
Brad Gardner

Re: Class Cast Exception on WebSession

[Igor Vaynberg <ig...@gmail.com>]

you have to declare it on the application.

-igor

On Sat, Nov 8, 2008 at 11:11 AM, Brad Gardner <bg...@gmail.com> wrote:
> Thank you!, this fixed the problem.  I'm not quite sure I understand the
> problem though.  Why does the newSession method need to be specified twice?
> Or did I just have it declared in the wrong class?
>
> On Sat, Nov 8, 2008 at 1:55 PM, Timo Rantalaiho <Ti...@ri.fi>wrote:
>
>> On Sat, 08 Nov 2008, Brad Gardner wrote:
>> >     public Session newSession(Request request, Response response)
>> >     {
>> >         return new CheeseStoreSession(request);
>> >     }
>>
>> You should have something like this in your Application
>> class, too, so that your CheeseStoreSession will be used.
>>
>> Best wishes,
>> Timo
>>
>> --
>> Timo Rantalaiho
>> Reaktor Innovations Oy    <URL: http://www.ri.fi/ >
>>
>
>
>
> --
> Brad Gardner
>

Re: Class Cast Exception on WebSession

[Brad Gardner <bg...@gmail.com>]

Thank you!, this fixed the problem.  I'm not quite sure I understand the
problem though.  Why does the newSession method need to be specified twice?
Or did I just have it declared in the wrong class?

On Sat, Nov 8, 2008 at 1:55 PM, Timo Rantalaiho <Ti...@ri.fi>wrote:

> On Sat, 08 Nov 2008, Brad Gardner wrote:
> >     public Session newSession(Request request, Response response)
> >     {
> >         return new CheeseStoreSession(request);
> >     }
>
> You should have something like this in your Application
> class, too, so that your CheeseStoreSession will be used.
>
> Best wishes,
> Timo
>
> --
> Timo Rantalaiho
> Reaktor Innovations Oy    <URL: http://www.ri.fi/ >
>



-- 
Brad Gardner

Re: Class Cast Exception on WebSession

[Timo Rantalaiho <Ti...@ri.fi>]

On Sat, 08 Nov 2008, Brad Gardner wrote:
>     public Session newSession(Request request, Response response)
>     {
>         return new CheeseStoreSession(request);
>     }

You should have something like this in your Application 
class, too, so that your CheeseStoreSession will be used.

Best wishes,
Timo

-- 
Timo Rantalaiho           
Reaktor Innovations Oy    <URL: http://www.ri.fi/ >