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From simon <simon.kitch...@chello.at>
Subject Re: Adding a property to a component and rendering it ... the magic way?
Date Mon, 17 Dec 2007 08:59:01 GMT
Hi Ole,

It is good to know that Facelets adds attributes automatically.

Yes, I guess it would be possible to modify
  HtmlRendererUtils.renderHtmlAttributes
to also look into the component it is passed for extra attributes that
it should write. It does mean retrieving the FacesContext from the
current thread and using that to get the configuration data (the names
of "magic" attributes) but that doesn't seem too evil to me.

But a ResponseWriter-based approach can do very much the same thing.

The advantage of doing it in HtmlRenderUtils is that it should work
better for components that output multiple HTML tags. In this case, the
renderer would normally invoke this method only for the "main" element.

However the advantage of doing it in ResponseWriter is that it will work
for all JSF components, not just the MyFaces ones. I think that is
extremely useful..

Regards,

Simon

On Mon, 2007-12-17 at 00:22 -0600, Ole Ersoy wrote:
> Good News - The tag attributes are automatically added to the UIComponent.attributes
map (At least they are by facelets).  That means it's possible to skip adding <f:attribute>
tags.
> 
> WRT the responseWriter feature, I think it would be sweet if we could configure valid
pass through attribute keys.  So for example:
> 
> <application>
>     <passthroughAttributes>
> 	<attribute name="comingOnThroughBeibe"/>
>     </passthroughAttributes>
> </application>
> 
> Then if the responseWriter saw the "comingOnThroughBeibe" key on one of the UIComponent.getAttributes()
entries it would render it.
> 
> I think that would have to be implemented on the HtmlRenderer utility methods though
(Moving away from the custom response writer idea a bit)?  A custom utility method would be
used by the renderer developer to pass through attributes that are "Hard Coded" for pass through,
as is currently done with the HTML constants, + any configured pass through attributes.
> 
> Thoughts?
> 
> Cheers,
> - Ole
> 
> 
> 
> 
> simon wrote:
> > Hmm..interesting suggestion, Andrew.
> > 
> > So a custom responsewriter could potentially be written to allow the
> > insertion of new attributes onto the html tag for any component?
> > 
> > Is this what you were thinking of?
> > 
> > startElement(String ename, UIComponent component) {
> >    // start xml element
> >    // if (component not in already-processed list)
> >    //   for each key in component.getAttributes()
> >    //     if key.startsWith("tunnelledAttribute:")
> >    //       output (key, value) as xml attributes
> >    // store component in already-processed list
> > }
> > 
> > Then:
> >   <h:someTag ..>
> >     <f:attribute name="tunnelledAttribute:foo" value="bar"/>
> > 
> > That might be interesting to add to the standard MyFaces
> > ResponseWriter...
> > 
> > Regards,
> > 
> > Simon
> > 
> > On Fri, 2007-12-14 at 19:54 -0700, Andrew Robinson wrote:
> >> Most renderers will not give you access to the root element to be able
> >> to add attributes. However, if the renderers are correctly using the
> >> response writer, they should be calling startElement(String,
> >> UIComponent). By subclassing this, you can trap the call, look for you
> >> attributes and add them to the element.
> >>
> >> -Andrew
> >>
> >> On Dec 14, 2007 7:07 PM, Ole Ersoy <ole.ersoy@gmail.com> wrote:
> >>> Hi,
> >>>
> >>> I have a attribute that I just need to get passed through to the corresponding
html element.  For example:
> >>>
> >>> <h:form id="registrationForm"
> >>>         anAdditionalAttribute="I need to get through to the form element">
> >>> </h:form>
> >>>
> >>>
> >>> In the rendered output I would like:
> >>>
> >>> <form
> >>>         ...
> >>>         anAdditionalAttribute="I need to get through to the form element">
> >>> </form>
> >>>
> >>>
> >>> I think the process for doing this (Excluding component registration, etc.)
is first to subclass the form component and add the "anAdditionalAttribute" to the subclass.
 Then subclass the corresponding renderer and render this attribute.
> >>>
> >>> Does anyone know if there's a quicker/magic way to get the job done?
> >>>
> >>> Thanks,
> >>> - Ole
> >>>
> >>>
> >>>
> > 
> > 


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