That's why I was pointing at mayTrackChangesFor().. I looked at the
method and I can't see a loophole, but there must be one to generate an
NPE, correct?
When I implemented the not-null check, I noticed exceptions still being
thrown from 2 other methods (if you search Page.java for versionManager,
you can see where there is the assumption that mayTrackChangesFor() is
checked for 'true', yet versionManager is never initialized in other
methods as well. So after adding the null check to each of these
methods, the application is working fine. Thing is, I've only seen this
exception when dealing with ajax (default not versioned, right?).
I will try and run a debugger through mayTrackChangesFor() with my
current app, and see the logic flow and why versionManager is ending up
null.
Aaron
Johan Compagner wrote:
> That is because the mayTrackChangesFor() method should only return true
> when it makes a version manager. Why is that not the case?
> If that method returns true the version manager can't be null because
> the version info must be tracked.
>
> johan
>
>
> On 3/1/07, *Aaron Hiniker* <[EMAIL PROTECTED]
> <mailto:[EMAIL PROTECTED]>> 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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