On Fri, 2007-12-14 at 20:07 -0600, Ole Ersoy 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?
Every component has an "attributes" property that is a map that anything
can be stored in. It is common for properties that are not used by the
component itself (just the renderer) to be stored in this map, rather
than be on the component. The renderer can then retrieve them by:
component.getAttributes().get("anAdditionalAttribute");
So that saves subclassing the component...
But the hard part is that to allow the tag to accept another attribute,
you need to subclass the tag class, and create a new taglib. Then your
page will need to use
<foo:form ...>
rather than
<h:form ...>
An alternative would be to write a custom tag that can be used to store
values into the attributes map of its enclosing component. Then
something like:
<h:form ....>
<foo:attribute name="anAdditionalAttribute" value="I need.."/>
could be used rather than creating a special tag for it.
As it happens, in MyFaces the standard f:attribute tag currently does
exactly this. Interestingly, it possibly shouldn't: the official JSF
docs say that it should only affect:
"the closest parent UIComponent custom action"
which I guess means it should walk up the component tree to find a
subclass of UICommand. I'll investigate what the Sun RI implementation
does...
If using f:attribute is acceptable to you, that avoids creating a new
tag class too, leaving just the renderer code to be done.
Regards,
Simon
