How-To dinamically add an attribute using "c:if" tag?

Question

Hi,
I have a problem with f:attribute tag.
I need to dinamically add an attribute to a h:panelGroup tag according to the value of a ELExpression. For example the fragment below should output an HTML page with two radio controls; depending to the clicked radio, the "foo" section or the "baz" section is showed (this is controlled client-side vie the javascript function called in the onclick event of the "foobaz" component):
<h:selectOneRadio id="foobaz" layout="lineDirection" value="#{myBean.foobazMode}" onclick="showHideFooBaz(this);">
  <f:selectItem itemValue="#{myBean.fooMode}" itemLabel="Show Foo"/>
  <f:selectItem itemValue="#{myBean.bazMode}" itemLabel="Show Baz"/>
</h:selectOneRadio>
<h:panelGroup id="foo">
  <c:if test="#{myBean.bazVisibile}">
    <f:attribute name="style" value="display: none"/>
  </c:if>
</h:panelGroup>
<h:panelGroup id="baz">
  <c:if test="#{myBean.fooVisibile}">
    <f:attribute name="style" value="display: none"/>
  </c:if>
</h:panelGroup>Well, the problem is this not work.
So my idea was to develop a new AttributeTag with a JSP body content in order to write:
<h:panelGroup id="foo">
  <my:attribute name="style">
    <c:choose>
      <c:when test="#{myBean.fooVisibile}">
        <f:verbatim>display: block</f:verbatim>
      </c:when>
      <c:otherwise>
        <f:verbatim>display: none</f:verbatim>
      </c:otherwise>
    </c:choose>
  </my:attribute>
</h:panelGroup>
...but don't work too.
Starting from the SUN JSF-RI AttributeTag, I developed my version extending from BodyTagSupport class instead of TagSupport one.
public class AttributeTag extends BodyTagSupport
    public int doStartTag() throws JspException {
        return (EVAL_BODY_INCLUDE);
    public int doEndTag() throws JspException {
       // Locate our parent UIComponentTagBase
        UIComponentClassicTagBase tag = UIComponentELTag.getParentUIComponentClassicTagBase(pageContext);
        if (tag == null) {
                throw new JspException("com.sun.faces.NOT_NESTED_IN_UICOMPONENT_TAG_ERRO");
        // Add this attribute if it is not already defined
        UIComponent component = tag.getComponentInstance();
        if (component == null) {
                throw new JspException("com.sun.faces.NO_COMPONENT_ASSOCIATED_WITH_UICOMPONENT_TAG");
        FacesContext context = FacesContext.getCurrentInstance();
        ELContext elContext = context.getELContext();
        String nameVal = null;
        Object valueVal = null;
        boolean isLiteral = false;
        int result = EVAL_PAGE;
        if (name != null) {
            nameVal = (String) name.getValue(elContext);
        if (value != null) {
            if (isLiteral = value.isLiteralText()) {
                valueVal = value.getValue(elContext);
        else
                BodyContent bodyContent = null;
                String content = null;
                String trimContent = null;
                if (
                        (bodyContent = this.getBodyContent()) == null
                        || (content = bodyContent.getString()) == null
                        ||  (trimContent = content.trim()).length() == 0
                        || (
                                trimContent.startsWith("<!--")
                        return result;
                valueVal = trimContent;;
                bodyContent.clearBody();
                isLiteral = true;
        if (component.getAttributes().get(nameVal) == null) {
            if (isLiteral) {
                component.getAttributes().put(nameVal, valueVal);
            else {
                component.setValueExpression(nameVal, value);
        this.release();
        return result;
}So guy, have you any idea of how to solve my problem?
Any help is very very appreciated!!
Regards,
-- Anthony

Answer 1

Hi BalusC
The first one is not for me because the "rendered" attribute is set on the server-side: the current "invisibl"e section would not be included in the renderer page (what I want is render the page displaying the current visible section and to switch to another section at client-side)
...but...
The second solution you propose is OK!!!! and so simple!!
Yeah man I really really thank you (sorry I didn't find the "?:" expression in the JSP manual http://java.sun.com/products/jsp/syntax/2.0/syntaxref20.html. Now looking again - and better - I find it as "ChoiceExpression")
Again, thanks!!!
-- Anthony