Custom JSTL Tag (extending BodyTagSupport) to generate javascript array when pass a java list

[Micale Raj]

Dear Friends,

I want to create a custom JSTL tag ( extending BodyTagSupport ) to generate javascript array when pass a java list. I'm new to JSTL and don't know how to start this. I want this new javascript variable to accessed by java script functions.
I think this is possible. How to do this ?

[Bear Bibeault]

Micale Raj wrote:I want to create a custom JSTL tag

There's no such thing as a "custom JSTL tag". The JSTL is a predefined tag library. I assume you mean a "custom tag"?

extending BodyTagSupport

You don't want to use BodyTagSupport -- that's JSP 1. You want to use JSP 2's SimpleTagSupport.

I'm new to JSTL and don't know how to start this.

That doesn't matter because this has nothing to do with the JSTL.

I want this new javascript variable to accessed by java script functions. I think this is possible. How to do this ?

You can emit any output you want, including JavaScript markup.

[Micale Raj]

Thanks for the reply. It should be custom tag. I can't use SimpleTagSupport since my project using JSP 1 . I'm trying to do this as following. But I'm getting error : No property editor found for the bean "java.util.List"

public class ListToJavaScriptArray extends BodyTagSupport {

	private List<String> list;

	public ListToJavaScriptArray(){
		super();
	}
	public void setList(List<String> list) {
		this.list = list;
	}

	public void release(){
		list = null ;
	}

	public int doStartTag() throws JspTagException {
		try {
			pageContext.getOut().write("");
			String text = "<script language=\"JavaScript\">var testList;" ;
			for( int k = 0 ; k < list.size() ; k++ ){
				text += " testList["+k+"]= " + list.get(k)+ ";";
			}
			text = "<script language=\"JavaScript\">";
			pageContext.getOut().write( text );
		} catch (IOException e) {
			throw new JspTagException(e.getMessage());
		}
		return EVAL_BODY_INCLUDE;

	}

}

The taglib.tld
<tag> <name>listToJavaScriptArray</name> <tag-class>ui.tags.ListToJavaScriptArray</tag-class> <body-content>JSP</body-content> </tag>

in Jsp Page,
<%@ taglib uri="/WEB-INF/taglib.tld" prefix="custom" %> <custom:listToJavaScriptArray list="a,b,c"/> ..... <script type="text/javascript"> function load() { // for test alert("Page is loaded " + testList ); } window.onload=load; </script>

[Bear Bibeault]

JSP 1? That's over 10 years old. There is no excuse for using something so old. What is the reason for this?

[Stefan Evans]

Extend your tld file to define the attribute of type list
That should look something like:

<attribute>
        <description>List to convert to javascript array.</description>
	<name>list</name>
	<required>true</required>
	<rtexprvalue>true</rtexprvalue>
	<type>java.util.List</type>
    </attribute>

Looking at your usage in the JSP page. How do you expect "a,b,c" to become a List?
That looks like a comma separated string to me...
# <custom:listToJavaScriptArray list="a,b,c"/>

[Micale Raj]

Stefan Evans wrote:Extend your tld file to define the attribute of type list
That should look something like:

<attribute>
        <description>List to convert to javascript array.</description>
	<name>list</name>
	<required>true</required>
	<rtexprvalue>true</rtexprvalue>
	<type>java.util.List</type>
    </attribute>

Looking at your usage in the JSP page. How do you expect "a,b,c" to become a List?
That looks like a comma separated string to me...
# <custom:listToJavaScriptArray list="a,b,c"/>

Thanks for the help.
I tried it and it worked. :)
You are right about jsp part. It's a comma separated string. I used a java.util.List from request build the array. Now it's working. Thank you very much ! :)