Here is a patch to org.apache.struts.taglib.template.InsertTag that allows
nested templates to work correctly.
Basically I wanted to get the effect of subclassing a template. Here is an
example, show what didn't work and what this patch fixes.
<!-- file template-base.jsp -->
<%@ page language="java" %>
<%@ taglib uri="/WEB-INF/struts-template.tld" prefix="template" %>
<HTML>
<BODY>
<H1>Title is <template:get name="title"/></H1>
</BODY>
</HTML>
<!-- file template-derived.jsp. This is a specialization of template-base,
which puts quotes around the template parameter. -->
<%@ page language="java" %>
<%@ taglib uri="/WEB-INF/struts-template.tld" prefix="template" %>
<template:insert template="template-base.jsp">
<template:put name="title">
'<template:get name="title"/>'
</template:put>
</template:insert>
<!-- page.jsp, inserts template-derived -->
<%@ page language="java" %>
<%@ taglib uri="/WEB-INF/struts-template.tld" prefix="template" %>
<template:insert template="template-derived.jsp">
<template:put name="title" content="Success" direct="true"/>
</template:insert>
<!-- end of example -->
When I display page.jsp in a browser, It will display
Title is ''
This is because the <template:get> tag in template-derived.jsp can't access
the value that inserted by <template:put> in page.jsp. The reason it doesn't
work is because InsertTag pushes a new ContentMap onto the ContentMapStack in
doStartTag(), so when <template:get> tries to access the "title" value put
there in page.jsp, it's not visible. This prevents templates from being
derived from like this.
The solution is simple. Just don't push the new ContentMap onto the stack
until the InsertTag.doEndTag() method. The GetTag and PutTag classes are
already written to support this, since the PutTag access the map from its
parent InsertTag rather than off the stack. I just moved the
ContentMapStack.push() call to doEndTag(), and now the above example works as
expected. GetTag has access to the ContentMap created by the inserting
page, but not to its immediate parent InsertTag's ContentMap.
Here is the patch.
Adam
Index: InsertTag.java
===================================================================
RCS file:
/home/cvspublic/jakarta-struts/src/share/org/apache/struts/taglib/template/InsertTag.java,v
retrieving revision 1.11
diff -u -r1.11 InsertTag.java
--- InsertTag.java 12 Mar 2002 05:55:08 -0000 1.11
+++ InsertTag.java 6 Apr 2002 08:48:18 -0000
@@ -128,23 +128,23 @@
}
/**
- * Process the start tag by pushing this tag's map onto the
- * content map stack.
- * See org.apache.struts.taglib.template.util.ContentMapStack.
+ * Process the start tag by creating this tag's map.
*/
public int doStartTag() throws JspException {
map = new ContentMap();
- ContentMapStack.push(pageContext, map);
return EVAL_BODY_INCLUDE;
}
/**
- * Process the end tag by including the template.
+ * Process the end tag by pushing this tag's map onto the
+ * content map stack and including the template.
+ * See org.apache.struts.taglib.template.util.ContentMapStack.
*/
public int doEndTag() throws JspException {
-
+
+ ContentMapStack.push(pageContext, map);
String prefix = "";
ApplicationConfig config = (ApplicationConfig)
pageContext.getServletContext().getAttribute(Action.APPLICATION_KEY);
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