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https://issues.apache.org/jira/browse/WICKET-4229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13151071#comment-13151071
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Martin Grigorov commented on WICKET-4229:
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Can you attach a quickstart app ?
This will save us some time.
Thanks !
> Expired Ajax Link Referencing Invalid PageID and Valid RenderCount Will
> Result In a ComponentNotFound Exception When The CallBack References A
> Component Built During A Page's onRender() Method - like GridView Components
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: WICKET-4229
> URL: https://issues.apache.org/jira/browse/WICKET-4229
> Project: Wicket
> Issue Type: Bug
> Components: wicket
> Affects Versions: 1.5.3
> Environment: Wicket 1.5.3
> Reporter: gotama
>
> While Wicket 1.5.3 addresses a situation where an ajax callback references a
> not yet existing component because the Session may have expired and the
> PageID referenced in the ajax callback link is invalid and returns a null
> page - and in turn, creates a new page via reflection - this will only work
> for accessing components which are created in the constructor of that newly
> created page, not the components created during the page's onRender() method,
> such as when GridView components are built by the page, this will result in a
> ComponentNotFound Exception.
> (example Wicket Ajax CallBack)
> ?11-3.IBehaviorListener.0-MyPanelNum1-MyPanelWithinAPanel-rows-19-cols-20-MyGridViewItemPanel-myContainerPanelCreatedDuringOnRender
> In the above Wicket rendered ajax link, the "11" refers to the PageID. The
> "3" is the RenderCount. The "rows" number and the "cols" number refers to
> components built by a GridView. GridView components are created during
> onRender(), not during the constructor. As such, if the Page is instantiated
> via reflection, the constructor is executed, not the onRender(), and
> therefore stepping through the Wicket 1.5.3 source code shows that in the
> above ComponentPath of
> "MyPanelNum1-MyPanelWithinAPanel-rows-19-cols-20-MyGridViewItemPanel-myContainerPanelCreatedDuringOnRender",
> this ComponentPath becomes invalid at "MyPanelNum1-MyPanelWithinAPanel-rows"
> (it has no child componets including "19") - this shows that while in fact
> the Wicket 1.5.3 fix to patch the situation where the PageID of "11" is
> invalid, and the isPageInstanceFresh() is true (the page was just created -
> as a new page is created if the PageID is a page store cache hit miss) and a
> new RenderPageRequestHandler is scheduled and the request recovers, the
> subsequent situation where this fix created that page, yet did not render it
> and its components, later becomes a cache hit and fails to find the
> components which are suppose to be created during onRender() and in turn
> missing during getComponent().
> Further complicating this scenario is that if in fact the referenced
> RenderCount ("3" in this example) in the ajax callback is in fact invalid,
> this situation is not reproducible because a stale page exception is thrown
> instead. However, in the edge case where the ajax callback is invalid due to
> the Session invalidating (a valid PageID may then now be 1 perhaps, not 11)
> and the RenderCount in the callback matches the stored page's RenderCount
> (just a matter of time for the RenderCounts to match), this will result in
> the ComponentNotFound exception - essentially a ticking RuntimeException to
> blow up the page, while tough to reproduce, is in fact valid and will occur.
> As a method of attempting to reproduce this issue, one can hi-jack the
> creation of this Wicket CallBack URL and induce this situation as follows:
> // int randomPageID = (int) (10 * Math.random());
> int randomPageID = 5;
> String myCallBackURL = myComponent.getCallbackUrl().toString();
> myCallBackURL = "?" + randomPageID + "-0" +
> myCallBackURL.substring(myCallBackURL.indexOf("."));
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