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https://issues.apache.org/jira/browse/WICKET-1213?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12549696
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Peter Ertl commented on WICKET-1213:
------------------------------------
here's an example of how this could be used -- you might get an better idea of
what I want to achieve with this patch...
this is some code inside my template page:
@Override
public AjaxRequestTarget newAjaxRequestTarget()
{
final AjaxRequestTarget target = super.newAjaxRequestTarget();
target.addListener(new AjaxRequestTarget.IListener()
{
@SuppressWarnings({"RawUseOfParameterizedType"})
public void onBeforeRespond(final Map map, final AjaxRequestTarget target)
{
// always render the feedback component that belongs to this template
// no need to include it in all pages that use this template
target.addComponent(feedbackPanel);
}
@SuppressWarnings({"RawUseOfParameterizedType"})
public void onAfterRespond(final Map map, final
AjaxRequestTarget.IJavascriptResponse response)
{
//
// set the focus on the first form component that has errors
// this is very convenient for the user as he doesn't have to click on
the erroneous field first
//
// this has to be rendered in onAfterRespond to be sure the dom
component for setting focus on has
// already been rendered in the dom structure of the browser
//
final FormComponent focus = (FormComponent)
visitChildren(FormComponent.class, new IVisitor()
{
public Object component(final Component component)
{
final FormComponent formComponent = (FormComponent) component;
if (formComponent.hasErrorMessage() &&
formComponent.getOutputMarkupId())
return formComponent;
return CONTINUE_TRAVERSAL;
}
});
if (focus != null)
target.focusComponent(focus);
}
});
return target;
}
another possible example (using common functionality specific to your
application this time)
@Override
public AjaxRequestTarget newAjaxRequestTarget()
{
return new CustomAjaxRequestTarget();
}
so inside your pages you could for example do this:
public void onClick(final AjaxRequestTarget target)
{
final CustomAjaxRequestTarget customTarget =
(CustomAjaxRequestTarget)target;
// change some setting on the page
// ..
// let the user take notice of the change (the heavily-used effect from
Ruby on Rails we probably all know)
customTarget.applyYellowFadeEffect(component);
// make it even more obvious (some freaky javascript :-)
customTarget.letScreenShakeUpAndDown();
// even half-blind people should see that (another crazy js)
customTarget.zoomInAndOutAgain(component);
}
this way you could provide some common ajax functionality to your application
which is easy to use and implementation details are perfectly hidden
> enable subclassing of AjaxRequestTarget
> ---------------------------------------
>
> Key: WICKET-1213
> URL: https://issues.apache.org/jira/browse/WICKET-1213
> Project: Wicket
> Issue Type: Wish
> Components: wicket
> Reporter: Peter Ertl
> Attachments: AjaxRequestTarget_with_subclassing.patch
>
>
> In my wicket programming experience so far I always didn't feel quite
> comfortable with the ajax part.
> I had some issues in particular with these as an example:
> - "Always include a common feedback panel from my template page"
> --> add 'target.addComponent(feedbackPanel)' just _everywhere_ (very
> cumbersome and not elegant at all)
> - add a listener using AjaxRequestTarget#addListener
> --> not possible without subclassing the request cycle (which is *yuk* if
> you ask me) to catch the short moment in between AjaxRequestTarget is
> instantiated and AjaxRequestTarget#onRespond() is called
> - automatically set focus on the first form component with errors
> --> add bulky code into all onSubmit() and onError() to check for errrors
> and call AjaxRequestTarget#setFocus
> - add some common function like AjaxRequestTarget#yellowFade(FormComponent)
> --> have some utility method and call it like this:
> AjaxUtil.yellowFade(target) -- not nice as functionality like this should
> really belong to the request target
> I found that all these issues can be solved very elegantly if you could just
> catch the moment where AjaxRequestTarget is instantiated.
> I attached a very little patch (!) which solves all that issues and makes
> ajax just a lot more powerful inside wicket *imho*
> also, it will not break current code but is just an enhancement you will not
> notice unless you need it.
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