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https://issues.apache.org/jira/browse/WICKET-5677?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14100578#comment-14100578
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Carl-Eric Menzel edited comment on WICKET-5677 at 8/18/14 12:21 PM:
--------------------------------------------------------------------
This is the new method's javadoc, different from my original proposal:
{code}
/**
* This method is called whenever a component is re-added to the page's
component tree, if it
* had been removed at some earlier time, i.e., if it is already
initialized
* (see {@link org.apache.wicket.Component#isInitialized()}).
*
* This is similar to onInitialize, but only comes after the component
has been removed and
* then
* added again:
*
* <ul><li>onInitialize is only called the very first time a component
is added</li>
* <li>onReAdd is not called the first time, but every time it is
re-added after having been
* removed</li>
* </ul>
*
* You can think of it as the opposite of onRemove. A component that
was once removed will
* not be
* re-initialized but only re-added.
*
* Subclasses that override this must call super.onReAdd().
*/
protected void onReAdd()
{code}
was (Author: cmenzel):
This is the new method's javadoc, different from my original proposal:
/**
* This method is called whenever a component is re-added to the page's
component tree, if it
* had been removed at some earlier time, i.e., if it is already
initialized
* (see {@link org.apache.wicket.Component#isInitialized()}).
*
* This is similar to onInitialize, but only comes after the component
has been removed and
* then
* added again:
*
* <ul><li>onInitialize is only called the very first time a component
is added</li>
* <li>onReAdd is not called the first time, but every time it is
re-added after having been
* removed</li>
* </ul>
*
* You can think of it as the opposite of onRemove. A component that
was once removed will
* not be
* re-initialized but only re-added.
*
* Subclasses that override this must call super.onReAdd().
*/
protected void onReAdd()
> Components should have onAdd to complement onRemove
> ---------------------------------------------------
>
> Key: WICKET-5677
> URL: https://issues.apache.org/jira/browse/WICKET-5677
> Project: Wicket
> Issue Type: Improvement
> Components: wicket
> Affects Versions: 6.16.0, 7.0.0-M2
> Reporter: Carl-Eric Menzel
> Assignee: Carl-Eric Menzel
>
> When a component is removed from the tree, onRemove is called on it and all
> its children, so they can do cleanup. When a component is added to the page,
> there is no similar call that could do initializations.
> Note: onInitialize sounds similar, but is actually rather different:
> onInitialize is called exactly once, the very first time the component is
> added to the page's component tree. It is basically a delayed constructor to
> allow superclasses to depend on (abstract) methods implemented by subclasses
> while giving the subclass's constructor a chance to run.
> onInitialize is not called again if a component is removed from the hierarchy
> and then added again. This happens, for example, in wizards, and in pages
> that replace panels to show different views.
> A good example is FencedFeedbackPanel, with the issue reported in
> WICKET-5265: in onRemove, the FFP clears the fence marker in its fence
> component. Stepping forward in a wizard where a step contains such an FFP
> causes onRemove to be called. Going backwards then re-adds the step panel and
> its FFP, but the fence is now broken, because the FFP has no way of knowing
> that it was re-added.
> I tried working around it using onConfigure and onBeforeRender. But due to
> the way Wicket traverses the component tree, it is not always guaranteed that
> this will be called soon enough, i.e. before an outer FFP has already
> "stolen" the feedback messages that should have been protected by the fence.
> I therefore propose adding a method onAddToPage that is called:
> - whenever a component or one of its parents is added to the page component
> tree, i.e. when it gets a connection to the page.
> - never more than once per add
> - never before the parent components are initialized.
> If a component is added to a container before the container is added to the
> page, this method should NOT be called - only when there is a path to the
> page.
> I have an implementation of this that is tested and fixes the problem in
> WICKET-5265. I'll push it to a branch as soon as I can. It's currently based
> on wicket-6.x but is easily portable to 7. It's not an API break, since only
> non-abstract methods are added.
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