Zen Water by darkpatator

Sometimes you want to check in your JSP page fragment which page loaded it.  Fortunately this is simple with JSTL.

<c:if test="${fn:indexOf(pageContext.request.requestURI,'foo.jsp') != -1}">
  The request URI ${pageContext.request.requestURI} contains foo.jsp.
</c:if>

Simple but something I always forget how to do.

Related posts:

1. JSTL for current URI
2. Get JSTL Vars from PageContext
3. Getting the request parameter

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"));

Related posts:

1. JSP Dynamo Request Retrieval
2. Accessing RepositoryItems with JSTL
3. JSTL for current URI

In JSP:

<%=request.getParameter("foo")%>
<img src="<%=request.getParameter("foo")%>">

In JSTL:

<c:out value="${param.foo}"/>

In DSP:

<dspel:valueof param="foo"/>

Related posts:

1. Comparison of DSP and DSPEL
2. Accessing RepositoryItems with JSTL
3. Display formatted HTML text

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.

1. The correct solution is to upgrade my application to use JSTL 1.1.  Then the JSTL expressions such as “${status.index}” will be evaluated by the container.  Then I don’t have to have a setter that takes a String parameter, the JSTL expression, and evaluate it myself.  I can just use a setter that takes an integer parameter.
2. The quick, hack solution which is to get rid of the setter that takes an integer parameter.  Wherever the application passes in an integer parameter, I change it to pass in a String representation of that integer.

Related posts:

1. Accessing JavaBean’s Getters and Setters
2. Size of collection in a JSP/DSP page
3. Accessing RepositoryItems with JSTL

1. Update URI in JSP pages to use JSTL 1.1.

   <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

2. Install in WEB-INF/lib the two JSTL 1.1 jars, standard.jar and jstl.jar.  You can get these from The Jakarta Site – Standard 1.1 Taglib Downloads.
3. Update the start of web.xml to look like this.

   <?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">

Related posts:

1. JSTL for current URI
2. Trim White Space from JSP
3. Size of collection in a JSP/DSP page

<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" />

Related posts:

1. Accessing RepositoryItems with JSTL
2. Trim White Space from JSP
3. Getting the request parameter

(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>

Related posts:

1. Get JSTL Vars from PageContext
2. JSTL for current URI
3. Upgrading to JSTL 1.1

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']}"/>

Related posts:

1. Get JSTL Vars from PageContext
2. Testing Which Page Loaded your JSP Page Fragment
3. Upgrading to JSTL 1.1

(Photo: leaf pile by oeimah)

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 " href="http://struts.apache.org/1.3.8/struts-taglib/tagreference.html#size">" href="http://struts.apache.org/1.3.8/struts-taglib/tagreference.html#size">" href="http://struts.apache.org/1.3.8/struts-taglib/tagreference.html#size"><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)}"/>

Related posts:

1. Trim White Space from JSP
2. ATG ForEach Output with Separators Between Items
3. Jumping to different parts of a page using a dropdown

  <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}

Related posts:

1. DynamicBeanMap
2. Comparison of DSP and DSPEL
3. ATG Currency Converter Not Working With JSTL c:set