The following tag of JSTL can be used to set a value to a variable in a request scope.
<c:set var="value" scope="request" value="someValue"/> I want to check conditionally, if the variable value being set is empty or not and display the result accordingly something like the following, using <c:when>...</c:when>.
<c:choose> <c:when test="${not empty value}"> <c:out default="None" value="${value}"/> </c:when> <c:otherwise> <c:out default="None" value="None"/> </c:otherwise> </c:choose> I want to reduce the line of code using a ternary expression like,
<c:out default="None" value="${not empty value ? value : 'None'}"/> It is evaluated as it actually means but if I interchange the order of the expressions like,
<c:out default="None" value="${empty value ? 'None' : value}"/> then it is a syntax error indicating,
"${empty value?'None':value}" contains invalid expression(s): javax.el.ELException: Error Parsing: ${empty value?'None':value}
So why does this happen?
I'm using the JSTL 1.1 library and the following taglib is included,
<%@taglib prefix="c" uri=""%> 1 Answer
I tested the following page in Tomcat 5.59, JSP 2.0 and JSTL 1.1. It ran without any errors.
<%@taglib uri="" prefix="c"%> <c:set var="value" scope="request" value="someValue"/> <c:out default="None" escapeXml="true" value="${not empty value ? value : 'None'}" /> <c:out default="None" escapeXml="true" value="${empty value ? 'None' : value}" /> <c:set var="value" scope="request" value="" /> <br/> <c:out default="None" escapeXml="true" value="${not empty value ? value : 'None'}" /> <c:out default="None" escapeXml="true" value="${empty value ? 'None' : value}" /> 
