I've experienced the exact same problem. You'll get this a lot when working
with ajax components. I've also reported this issue to the wicket 2 jira. If
you add if(versionManger != null) prior to the versionManager call you'll be
fine but that's probably an ugly hack. But it seem to work til they've
actually fixed it.
Aaron Hiniker-2 wrote:
>
> I pulled the latest from trunk. And I am getting this NPE:
>
> 16:30:14,543 ERROR [STDERR] java.lang.NullPointerException
> 16:30:14,544 ERROR [STDERR] at
> wicket.Page.componentStateChanging(Page.java:327)
> 16:30:14,545 ERROR [STDERR] at
> wicket.Component.addStateChange(Component.java:2553)
> 16:30:14,545 ERROR [STDERR] at
> wicket.Component.setModel(Component.java:2191)
> 16:30:14,545 ERROR [STDERR] at
> wicket.MarkupContainer.setModel(MarkupContainer.java:596)
> 16:30:14,546 ERROR [STDERR] at
> com.edicorp.erp.web.components.search.ProductSearchPanel.query(ProductSearchPanel.java:144)
> 16:30:14,546 ERROR [STDERR] at
> com.edicorp.erp.web.components.search.ProductSearchPanel.onUpdate(ProductSearchPanel.java:109)
> 16:30:14,546 ERROR [STDERR] at
> com.edicorp.erp.web.components.search.FilterPanel.fireOnChange(FilterPanel.java:74)
> 16:30:14,547 ERROR [STDERR] at
> com.edicorp.erp.web.components.search.query.QueryPanel$QueryForm.onSubmit(QueryPanel.java:197)
> 16:30:14,547 ERROR [STDERR] at
> wicket.markup.html.form.Form.delegateSubmit(Form.java:680)
> 16:30:14,547 ERROR [STDERR] at
> wicket.markup.html.form.Form.onFormSubmitted(Form.java:396)
> 16:30:14,547 ERROR [STDERR] at
> sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>
>
> I remember I was getting this NPE before, and I patched the source to
> include this null check in Page.java:
>
> final void componentStateChanging(final Component component,
> Change change)
> {
> checkHierarchyChange(component);
>
> dirty();
> if (mayTrackChangesFor(component, null))
> {
> if ( versionManager != null )
>
> versionManager.componentStateChanging(change);
> }
> }
>
> It seems that everywhere else in Page.java there is a null check for
> versionManager, except in this method. Not sure, but perhaps the
> problem lies in the #mayTrackChangesFor() method, but in any case if I
> add this null check my code runs fine.
>
> Aaron
>
>
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