How to evaluate a scriptlet variable in EL?

Question

I was wondering if there was anyway of using JSP in <c:if> statement.

E.g.

<c:if test="${ param.variable1 == 'Add' <% JSP variable clause %>}">

So I want my JSP variable to checked against as well.

Any suggestions? I have tried ignorantly just sticking in the clause, obviously it did not work.

Thanks

Heartstricken

Answer 1

So you want to evaluate a scriptlet variable in EL? Store it as a request attribute. The below example will make it available as ${foo}.

<%
    String foo = "some";
    request.setAttribute("foo", foo);
%>

<c:if test="${param.variable1 == 'Add' && foo == 'some'}">

However, this makes no sense. You should avoid scriptlets altogether and use JSTL/EL to prepare this variable. So if you make the functional requirement more clear, e.g. "How do I do this (insert scriptlet code snippet) using JSTL/EL?", then we'll be able to suggest the right approach.

For example, you could use <c:set> to set a variable in EL scope.

<c:set var="foo" value="some" scope="request" />

Or if the JSP is forwarded by a servlet, then use request.setAttribute() over there right away.

String foo = "some";
request.setAttribute("foo", foo);
request.getRequestDispatcher("/WEB-INF/your.jsp").forward(request, response);

This will then be available as ${foo} the same way.

See also:

• Our EL wiki page
• Difference between <%= foo %> and ${ foo }
• Use EL ${XY} directly in scriptlet <% XY %>
• What are implicit objects? What does it mean?
• Generate an HTML Response in a Java Servlet

Bosket

Just trying to experiment I tried not adding it to the request scope figuring it would be available in the page scope anyways. So I explicitly requested it from the page scope using in the EL: pageScope.var. Sure enough, it didn't work. Weirdly, when simply using var in the EL it does work without having to place the variable in the scriptlet code in request scope. What am I missing? – Aciculate

Why use request context? Simpler, more local, is <% pageContext.setAttribute("var", "some"); %> – Larisa