Passing a hashmap to a tag file

[Nauman Hasan]

Hi folks,

I am using Tag Files with JSP and ran into a puzzling issue. Just as background I am using JDK 1.6 and Apache Tomcat 6.0.33. In short the same code in tag seems to be causing a exception. So what I am wondering is if there is translation occuring in between the JSP and Tag file (even with tag attribute is marked as dynamic). Thanks for your help!

In the main JSP page I have the following (snippets)

<%@ taglib prefix="tags" tagdir="/WEB-INF/tags" %>
...
<c:forEach items="${myMap}" var="myItem">
	<br/>Item:${myItem.key}:${myItem.value}:${myItem}
</c:forEach>
...
<tags:replacements color="blue" replaceMap="${myMap}">

The output is

Item:start:myStart:start=myStart
Item:mid:myMid:mid=myMid
Item:end:end:end=end 

In the tag file I have following code snippets

<%@ attribute name="replaceMap" rtexprvalue="true" %>
...
<c:forEach items="${replaceMap}" var="rm">
	<br/>:${rm}:
</c:forEach>
...
<c:forEach items="${replaceMap}" var="rm1">
	<br/>Item:${rm1.key}:${rm1.value}:${rm1}
</c:forEach>

If don't put in the last forEach then I get

:{start=myStart:
: mid=myMid:
: end=end}: 

Otherwise there is an exception

Dec 4, 2011 7:41:21 AM org.apache.catalina.core.ApplicationDispatcher invoke
SEVERE: Servlet.service() for servlet jsp threw exception
javax.el.PropertyNotFoundException: Property 'key' not found on type java.lang.String
	at javax.el.BeanELResolver$BeanProperties.get(BeanELResolver.java:214)
	at javax.el.BeanELResolver$BeanProperties.access$400(BeanELResolver.java:191)
	at javax.el.BeanELResolver.property(BeanELResolver.java:300)
	at javax.el.BeanELResolver.getValue(BeanELResolver.java:81)
	at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:54)
	at org.apache.el.parser.AstValue.getValue(AstValue.java:123)
	at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
	at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:938)
	at org.apache.jsp.tag.web.replacements_tag._jspx_meth_c_005fforEach_005f1(replacements_tag.java:193)
	at org.apache.jsp.tag.web.replacements_tag.doTag(replacements_tag.java:107)

Any help would be appreciated.

~Nauman

[Stefan Evans]

You are missing a vital element in the declaration of the attribute in your tag file:

<%@ attribute name="replaceMap" rtexprvalue="true" type="java.util.Map" %>  

Unless you specify the type, it assumes the attribute you are declaring is a String.
Doing a <c:forEach> over a String is valid (assumes it is a comma separated list of strings, and so returns each element as a String)
Hence why the first loop 'works' but the second one failed.

[Nauman Hasan]

You sir and fabulous!

Thanks it works now

~Nauman