Sometimes you want to check in your JSP page fragment which page loaded it. Fortunately this is simple with JSTL.
[xml]<c:if test="${fn:indexOf(pageContext.request.requestURI,’foo.jsp’) != -1}">
The request URI ${pageContext.request.requestURI} contains foo.jsp.
</c:if>[/xml]
Simple but something I always forget how to do. 🙂
JSTL sets its vars in the pageContext. For example:
pageContext.setAttribute("foo", bar);
Therefore to get a JSTL variable use the pageContext within a tag or a JSP page. For example:
// get item from pageContext and put in request
atg.servlet.DynamoHttpServletRequest drequest = atg.servlet.ServletUtil.getDynamoRequest(request);
drequest.setParameter("foo", pageContext.getAttribute("foo"));
Note that getAttribute assumes the variable is in the page scope. If you want to get a variable from for example the request scope you would do this.
pageContext.getAttribute("foo", javax.servlet.PageContext.REQUEST_SCOPE);
For further reading please see PageContext.
I was getting a JSP compilation problem that I could not solve.
org.apache.jasper.JasperException: Unable to compile class for JSP
at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:375)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
org.apache.jasper.JasperException: Unable to compile class for JSP
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:572)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:303)
java.lang.NumberFormatException: For input string: "${status.index}"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:447)
at java.lang.Integer.valueOf(Integer.java:553)
at org.apache.jasper.compiler.JspUtil.coerceToInt(JspUtil.java:752)
at org.apache.jasper.compiler.Generator$GenerateVisitor.convertString(Generator.java:2949)
The major problem was this was happening on the server but not locally. The compilation problem was occurring for this line.
<uportal:module definition="${module}" moduleIndex="${status.index}"/>
The moduleIndex value is “${status.index}”. Locally when the JSP compiler encounters this it knows to call my setter for moduleIndex that takes a String parameter. But on the server the JSP compiler seemed to insist on using the setter for moduleIndex that takes an integer parameter, hence the compilation problem.
I finally posted on the Sun Forums and with the help of evnafets I came up with two solutions.
Based on this excellent post I came up with the following instructions for upgrading from JSTL 1.1.
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
In DSP to display formatted HTML text you use the valueishtml converter attribute. For example:
<dspel:valueof param="displayName" valueishtml="true"/>
For example “foo & bar” becomes “foo & bar”.
In JSTL to do this you tell JSTL not to escape the XML. For example:
<c:out value="${displayName}" escapeXml="false" />
(Photo: Singur suflet pustiu by dani81_const)
This article, Expression Language Overview” href=”http://www.informit.com/articles/article.aspx?p=30946″>InformIT: The JSTL Expression Language > Expression Language Overview, informed me on how to test if something is empty or not.
Empty?
<c:if test="${empty foo}">...</c:if>
Not empty?
<c:if test="${not empty foo}">...</c:if>
I was wondering how do get the current URI using JSTL and found this forum thread, JSTL EL for current page URL?.
If you want the actual URI of the JSP that is being rendered:
<c:out value="${pageContext.request.requestURI}"/>
If you want the original URI, which is probably the case, then:
<c:out value="${requestScope['javax.servlet.forward.request_uri']}"/>
In DSP if you want the original URI you can use the OriginatingRequest bean which implements the HttpServletRequest.
<dsp:valueof bean="/OriginatingRequest.requestURI" />
Sometimes in a JSP/DSP page you will want to get the size of a collection and unless you are within a Range, ForEach or similar droplet you won’t have access to this value.
Struts has a nice solution using the bean:size tag. JSTL 1.1 has a nice solution using the fn:length function.
Here is an example of how to use Struts, DSPEL and JSTL to get the size of a collection.
<dspel:getvalueof param="book.pages" var="pages"
vartype="java.util.Collection"/>
<bean:size id="numPages" name="pages"/>
Number of Pages: <c:out value="${numPages}"/>
Number of Pages: <dspel:valueof value="${numPages}"/>
Here is an example of how to use JSTL 1.1 and DSPEL to get the size of a collection.
<dspel:getvalueof param="book.pages" var="pages"
vartype="java.util.Collection"/>
Number of Pages: <c:out value="${fn:length(pages)}"/>
Often we are accessing repository items in a JSP page like this.
<dspel:droplet name="RQLQueryForEach" var="query">
<dspel:param name="repository" bean="/betweengo/repository/Repository"/>
<dspel:param name="itemDescriptor" value="Account"/>
<dspel:param name="queryRQL" value="ALL"/>
<dspel:setvalue param="account" paramvalue="element"/>
<dspel:oparam name="output">
<dspel:valueof param="account.name"/><br/>
</dspel:oparam>
</dspel:droplet>
With JSTL we could try to display the name like this.
<c:out value="${query.account.name}"/>
If you are using JSP 2.0 you can display it even more simply.
${query.account.name}
However since account is a RepositoryItem object and there is no get method for the name property (i.e. it’s not a JavaBean object) the above will fail and produce an exception.
To get around this you can extend ATG’s RQLQueryForEach class by overriding the protected setElementParameter. In addition to setting the element parameter in the request you can set a new parameter which we will call “item”. This item is of class atg.beans.DynamicBeanMap and wraps a RepositoryItem.
public class RQLQueryForEachEL extends RQLQueryForEach {
protected void setElementParameter(DynamoHttpServletRequest pRequest,
String pElementName, Object pValue) {
super.setElementParameter(pRequest, pElementName, pValue);
DynamicBeanMap itemBean = new DynamicBeanMap(pValue, true);
pRequest.setParameter("item", itemBean);
}
}
Now we can access the repository item with JSTL like this.
${query.item.name}