JavaServer Pages (JSP) and JSTL - conditional attribute - how to
Hi,
I'm writing JSP document, so the jsp must be well formed.
I want to set the background of even and odd table rows by adding a class only on even rows (to avoid unnecessary source - network traffic).
Something like
if (even)
<tr class="even>
else
<tr>
How can this be done in JSP documents?
I've tried many approaches with JSTL,... but the "problem" is that condition can only be checked with <c:if> and <jsp:attribute> within <c:if> sets the attribute to <c:if>.
What am I missing?
Any ideas?
# 1
<tr class="<%= even ? "even" : "odd" %>">Untested tho, I don't use JSP. Maybe you've to use ${even ? 'even' : 'odd'}. But you hopefully got the point.
# 2
this might work and is the current "solution"
but the point is to omit the
class="odd"
since it is not necessary and causes additional network traffic
even rows should be
<tr class="even">
odd rows should be
<tr>
(without any class)
# 3
Well, it's a small change ..
<tr<%= even ? " class=even" : "" %>>Remove the first > after tr. The dumb parser of this forum doesn't handle nested < and > correctly. But you got the point? Just move "class=" to the expression and keep the other hand empty ..
Message was edited by:
BalusC
# 4
this doesn't work in jsp document since as a well formed xml all attributes must have name and valuethe whole jsp expression is recognized as attribute name and the jsp document does not compile
# 5
try this:<tr <c:if test="${even}">class="even"</c:if>>
# 6
I wanted to say without the closing ">" that comes right after "<tr"
# 7
unfortunately this also does not compileexception says there must be an attribute specification after tr
# 8
you have to put these lines at the top of JSP:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
And it must work because on my machine does. If not paste here the JSP fragment.
# 9
as I already mentioned - I'm writing jsp documents
so here are the fragments
<?xml version="1.0" encoding="UTF-8" ?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" xmlns:ebp="EBP.tld" xmlns:c="http://java.sun.com/jsp/jstl/core" xmlns:fmt="http://java.sun.com/jsp/jstl/fmt" version="2.0">
<jsp:directive.page session="false" language="java" contentType="application/xhtml+xml; charset=UTF-8"
pageEncoding="UTF-8" />
.....
<tr <c:if test="${!empty clazz}"><jsp:text> class="${clazz}"</jsp:text></c:if> >
........
and the (german) exception
com.ibm.ws.jsp.JspCoreException: /WEB-INF/jsp/umappe/auftragsTRs.jspx(39,9) /WEB-INF/jsp/umappe/auftragsTRs.jspx(39,9) Nach dem Elementtyp "tr" msen Attributspezifikationen, ">" oder "/>" folgen.
at com.ibm.ws.jsp.translator.document.Jsp2Dom.parseToDom(Jsp2Dom.java:334)
at com.ibm.ws.jsp.translator.document.Jsp2Dom.getJspDocument(Jsp2Dom.java:166)
at com.ibm.ws.jsp.translator.JspTranslator.<init>(JspTranslator.java:67)
# 10
try this:
<tr <c:if test="${!empty clazz}">class=<c:out value="${clazz}"/></c:if> >Which are the implementations for JSTL ? (apache ?)
# 11
I think there is Apache JSTL running in Websphere, but I don't think it is a JSTL problem.
The jsp source
<tr <c:if test="${!empty clazz}">class=<c:out value="${clazz}"/></c:if> >
is not well formed xml as it must be for jsp document so it can not be parsed as indicated also by part of stacktrace in error message:
at com.ibm.ws.jsp.translator.document.Jsp2Dom.parseToDom(Jsp2Dom.java:334)
at com.ibm.ws.jsp.translator.document.Jsp2Dom.getJspDocument(Jsp2Dom.java:166)
at com.ibm.ws.jsp.translator.JspTranslator.<init>(JspTranslator.java:67)
# 12
is not well formed xml as it must be for jsp document
so it can not be parsed as indicated also by part of
stacktrace in error message:
It is not necessary to be well formed xml so that JSP to work. Just do not put the constraint for well formed and it will compile and work.
# 13
maybe well formed would be like this:
<tr <c:if test="${!empty clazz}"><c:out value="class=${clazz}"/></c:if> >
# 14
tags within tags can not be well formed so the
<c:if in <tr breaks xml
I need to write the jsp as a jsp document. One point is that jsp documents do not produce any whitespace.
I believe there is no way to come around the
<tr class="odd">, although it is useless code (<tr> would be enough).
# 15
You also can do this class alternation for rows from javascript (in onload function). So, you will have no traffic regarding this.
# 16
unfortunately not since the whole application is designed to work completely without javascript as well as with (the user can turn off javascript at any time)
