Problem with rendering of the Palette component

[Jelena Jovanovic <jo...@fon.bg.ac.yu>]

Hello,

I have a problem with the Palette component. I keep receiving
NullPointerException and the stack trace as follows:

*
org.apache.tapestry.contrib.palette.Palette.handleSubmission(Palette.java:48
9) 

*
org.apache.tapestry.contrib.palette.Palette.renderComponent(Palette.java:285
) 

*
org.apache.tapestry.AbstractComponent.render(AbstractComponent.java:857) 

*
org.apache.tapestry.AbstractComponent.renderBody(AbstractComponent.java:624)


*
org.apache.tapestry.form.Form.renderComponent(Form.java:362) 

*
org.apache.tapestry.AbstractComponent.render(AbstractComponent.java:857) 

*                       org.apache.tapestry.form.Form.rewind(Form.java:568) 

.

 

I checked I don't even know how many times the specification of the
component but I can't spot the mistakes. Here it is:

 

<property-specification name="subTopicsOfInterest" type="java.util.List"
persistent="yes"/>

<property-specification name="topicsModel"
type="org.apache.tapestry.form.IPropertySelectionModel"/>

 

<component id="selectTopics" type="contrib:Palette">

      <binding
name="sort">@org.apache.tapestry.contrib.palette.SortMode@USER</binding>

      <binding name="model" expression="topicsModel"/>

      <binding name="selected" expression="subTopicsOfInterest"/>

      <binding name="selectedTitleBlock"
expression="components.selectedTitleBlock"/>

      <binding name="availableTitleBlock"
expression="components.availableTitleBlock"/>

</component>

 

I did not make the model persistent since it should be filed with a new set
of values each time the page is presented to the user.

 

If I try to submit the form without making any selection in the Palette
component, everything is fine. However, if I make a selection and then
submit the page I get the exception and the stack trace presented above.

 

Can anyone give some advice? I really do not have ideas how to solve this
problem.

Thanks in advance!

Jelena