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https://issues.apache.org/jira/browse/WICKET-5460?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sven Meier resolved WICKET-5460.
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Resolution: Fixed
Fix Version/s: 7.0.0
6.14.0
FLAG_PREPARED_FOR_RENDER is now reset
> onBeforeRender called too early on stateless page
> -------------------------------------------------
>
> Key: WICKET-5460
> URL: https://issues.apache.org/jira/browse/WICKET-5460
> Project: Wicket
> Issue Type: Bug
> Components: wicket
> Affects Versions: 6.12.0, 7.0.0
> Reporter: Martin Geisse
> Assignee: Sven Meier
> Fix For: 6.14.0, 7.0.0
>
> Attachments: beforerender-bug.zip
>
>
> I'm having a problem with a ListView that displays an outdated list.
> In my test, the ListView uses a Model that returns a static variable just to
> make sure the model is independent from any page instance. As far as I can
> tell, this problem has nothing to do with the model, but with the way Wicket
> prepares for a request listener invocation.
> The exact setup is this:
> - the page contains a ListView and (outside of the list) a Link that
> adds an item to the list in its onClick(). The list itself is stored
> in a static variable.
> - the page is stateless
> - the page's components are created in onInitialize()
> Result:
> The list doesn't show the most recently added item. Reloading the
> original page shows the correct list. Note that by "reloading" I mean
> entering the page's original URL since the browser's address bar now contains
> the request listener URL due to the page being stateless.
> This is how I think is happens:
> - Initially rendering the page works fine. The page is then discarded
> since it's stateless.
> - Clicking on the link creates a new page instance to invoke the
> link's request listener.
> - IPageAndComponentProvider.getComponent() cannot find the link yet
> since it is not created until onInitialize() has been called.
> - as a consequence, it calls page.internalInitialize() and
> internalPrepareForRender(false)
> - this creates the link, but it also creates the ListView and prepares
> it for rendering. This in turn polls the ListView's model and creates
> list items. It also marks the ListView as "prepared for render", which
> is the crucial point.
> - The link's request listener runs and adds an item to the list.
> - After the request listener handler, the page render handler runs
> - That handler renders the page, including the ListView
> - ... but it doesn't call onBeforeRender() on the ListView anymore,
> because it's already marked as "prepared for render"! So it doesn't
> pick up the new, up-to-date list from its model.
> I'm not sure if I'm "doing it wrong", but then it doesn't seem quite
> right that onBeforeRender() gets called before invoking the listener,
> but not actually before rendering. There's probably some kind of logic
> behind the decision to run onBeforeRender() only when this hasn't yet
> happened, right? Is there a general way to "unprepare" the component
> in onClick()?
> ---
> Re: #internalPrepareForRender(false) should not mark the page as rendered
> (thus the false parameter).
> The problem is, I think, not that the component is being marked as
> *rendered*, but as *prepared for render*. From class Component:
> protected void onBeforeRender()
> {
> setFlag(FLAG_PREPARED_FOR_RENDER, true);
> onBeforeRenderChildren();
> setRequestFlag(RFLAG_BEFORE_RENDER_SUPER_CALL_VERIFIED, true);
> }
> Note the first line. This causes subsequent invocations of
> internalBeforeRender() to skip the relevant part.
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