Spec oversight? Using dynamic-attributes in XML tag files

Question

I have a couple of tagfiles that generate form elements with specific conventions for the 'name' and 'value' attribute. Basically, a data binding framework.
Dynamic attributes are useful because you can delegate all the usual html attributes to the generated HTML form element: SELECT, INPUT, id, class etc.
The usual way to do this is to concatenate all the "pass-through" attributes to a string, and append this string to the element generated:
<input type="hidden" name="foo" ${dynattrs}/>I'm wondering how to do this in a tagfile in XML format (mytag.tagx), since the XML format forbids syntax like in the example above.
jsp:attribute won't help much, if it's nested inside a c:forEach: it won't apply to the right element.

Answer 1

Ran into the same problem with 'optional attributes'. (see post "JSP 2.0 Tag files outputting elements with conditional attributes" http://forum.java.sun.com/thread.jspa?forumID=45&threadID=681033)
Found a solution that is not very elegant but does work and saves you the trouble of reverting to Java Tags. Consider the following tag-file that outputs an html input-tag with conditional attributes:
<?xml version="1.0" encoding="utf-8"?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2"
     xmlns:c="http://java.sun.com/jsp/jstl/core">
     <jsp:directive.attribute name="name" required="true" type="java.lang.String"/>
     <jsp:directive.attribute name="id" required="false" type="java.lang.String"/>
     <jsp:directive.attribute name="value" required="false" type="java.lang.String"/>
     <jsp:directive.attribute name="disabled" required="false" type="java.lang.Boolean"/>
     <jsp:directive.attribute name="hint" required="false" type="java.lang.String"/>
     <jsp:directive.attribute name="cssClass" required="false" type="java.lang.String"/>
     <jsp:text><![CDATA[<input type="text" name="]]><c:out value="${name}"/><![CDATA["]]></jsp:text>
     <c:if test="${!empty id}"><![CDATA[ id="]]><c:out value="${id}"/><![CDATA["]]></c:if>
     <c:if test="${!empty cssClass}"><![CDATA[ class="]]><c:out value="${disabled?(cssClass + '-disabled'):cssClass}"/><![CDATA["]]></c:if>
     <c:if test="${disabled}"><![CDATA[ disabled="disabled"]]></c:if>
     <c:choose>
          <c:when test="${!empty value}"><![CDATA[ value="]]><c:out value="${value}"/><![CDATA["]]></c:when>
          <c:when test="${!empty hint}"><![CDATA[ value="]]><c:out value="${hint}"/><![CDATA[" onfocus="if(this.value==']]><c:out value="${hint}"/><![CDATA[')this.value='';"]]></c:when>
     </c:choose>
     <jsp:text><![CDATA[/>]]></jsp:text>
</jsp:root>In answer to your question: Yes, it looks like an oversight. Using the jsp:attribute tag in a c:forEach doesn't work because the attribute is then applied to the forEach tag. You would have to put the attribute-tag inside a jsp:body tag (inside the forEach). Then it would apply not to the forEach tag but to the tag enclosing the forEach. However, this doesn't work either, or at least it doesn't work in Tomcat 5.5. Could be a bug though, JSP 2.0 is still very buggy (for instance, using a tagfile inside another tagfile from the same taglib doesn't seem to work either...)
Anyway, if you ever find a good solution please let me know by posting to this topic!
TIA