Problem using tags as an attribute for other tags.

Question

Hi there,
I'd like to know if there is a way to use a tag as an attribute for an other tag.
Exemple :
<user:testparent param="<user:param param='1' />" >
When doing so, the value of param is <user:param param='1'/>, and not the value that should be returned by the <user:param /> tag.
Is there a way to use the value returned by this tag as a parameter ?
With text, the correct value returned by the tag is used, so I guess it's possible to do so with custom tags.
Thanks.

Answer 1

Okay, here is an example of the process...
I have this Class that acts as the parent to all the tags that I use:
package net.thelukes.steven.scriptbits;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;
//Other Imports ...
public abstract class ScriptBitsTag extends BodyTagSupport  {
     public int doAfterBody() throws JspException {
          return TagSupport.SKIP_BODY;
     public int doEndTag() throws JspException {
          return TagSupport.EVAL_PAGE;
     /* All subclasses of ScriptBitsTag should call super.doStartTag()
      * at the begining of their own doStartTag();
     public int doStartTag() throws JspException {
          initAttributes();
          return TagSupport.SKIP_BODY;
     public abstract  void setAttributeValue(String attributeName, String attributeValue);
     public abstract String getAttributeValue(String attributeName);
     /* Use this method to initialize attributes at the start of tag execution */
     public abstract void initAttributes();
     //...So, for example, I will have a sb:slidingFrame tag that looks like this:
package net.thelukes.steven.scriptbits;
// Imports...
public class SlidingFrameTag extends ScriptBitsTag {
     private java.util.Map<SlidingFrameAts,String> attributes =
               new java.util.EnumMap<SlidingFrameAts,String>(SlidingFrameAts.class);
     public int doStartTag() throws JspException {
          super.doStartTag();
          //... Do initialize here
          return TagSupport.EVAL_BODY_INCLUDE;
     public int doEndTag() throws JspException {
          //... Do work that depends on nested parameter values here...          
          return TagSupport.EVAL_PAGE;
     //Normal setXXX methods for attributes... <sb:slidingFram windowID="..." >
     public void setWindowID(String name) {
          windowName = name;
     //Do What should happen when nested tag does its work...
     //     <sb:slidingFrame><sb:attribute .../></slidingFrame>
     //For me, just put values in proper place in map...
     public void setAttributeValue(String name, String value) {
          SlidingFrameAts attrib = SlidingFrameAts.valueOf(name);
          if (attrib == null)
               return;
          else if (attrib == SlidingFrameAts.useDefaultStyleSheet)
               this.setUseDefaultStylesheet(Boolean.valueOf(value));
          else if (attrib == SlidingFrameAts.offX)
               attributes.put(attrib, value);
          else {
               nonDefaultInit = true;
               attributes.put(attrib, value);
     public String getAttributeValue(String name) {
          return attributes.get(SlidingFrameAts.valueOf(name));
     //Set Default values for all attributes.
     public void initAttributes() {
}So now I have a tag that is designed to be nested inside ScriptBitsTags and provide attributes for them:
package net.thelukes.steven.scriptbits;
//includes
public class ScriptBitsAttributeTag extends BodyTagSupport {
     private String attName = null;
     private String attVal  = null;
     //Normal set methods for in tag attribes: <sb:attribute name="..." value="..."/>
     public void setName(String name) {
          attName = name;
     public void setValue(String value) {
          attVal = value;
     public int doEndTag() throws JspException {
          //If value not set yet, it should come from the tag's body
          //<sb:attribute name="...">Some Value</sb:attribute>
          if (attVal == null) {
               if (bodyContent != null && bodyContent.getString() != null) {
                    attVal = bodyContent.getString().trim();
               } else {
                    //If not found in body, then use empty string for value...
                    //(or some appropriate value....)
                    attVal = "";               
          setAttribute();
          return TagSupport.EVAL_PAGE;
     //Assign the attribute to the this tag's parent.
     private void setAttribute() {
          ScriptBitsTag parentTag =
               (ScriptBitsTag)TagSupport.findAncestorWithClass(this, ScriptBitsTag.class);
          parentTag.setAttributeValue(attName, attVal);          
}The TLD has the SlidingFrame tag look like this:
  <tag>
    <description>Sliding Menu Window</description>
    <display-name>SlidingWindow</display-name>
    <name>slidingWindow</name>
    <tag-class>net.thelukes.steven.scriptbits.SlidingFrameTag</tag-class>
    <body-content>jsp</body-content>
    <!-- attributes available for in tag sb:slidingFram windowID="..." for example -->
    <!-- set required to false to allow the attribute to be set by sb:attribute tag -->
  </tag>The rest of the tld is pretty standard... In my JSP I then have:
<sb:slidingFrame windowID="sliding_frame">
  <%-- Attribute Set for this sliding frame --%>
  <sb:attribute name="speed">
    <c:out value="${sessionScope.speedV}"/>
  </sb:attribute>
  <%-- Content of the sliding frame --%>
  Menu Item A<br/>
  Menu Item B<br/>
  Menu Item C<br/>
  <hr/>
  Menu Item A<br/>
</sb:slidingFrame>In this case, instead of doing:
<sb:slidingFrame speed="<sb:attribute value='whatever'/>">I nested the attribute tag between sb:slidingFrame's open and close tag. You have to make sure that any work you want to do that depends on the value of speed is done in the doEndTag so as to make sure it occurs after the nested tag does its work.