Question

I have something like in my JSP page :

<% if(id!=null) { %>
     <input type="hidden" name="id" value="<%= id %>" />
<%
}
%>

When I want to edit a user id should be non null, then I want that input in my HTML.
However, when I want to add a user id should be null, and so I don’t what that input.

It works great with that code. But I would like to use JSTL i tried using c:if and c:when :

<c:choose>
    <c:when test="${id != null }">
        <input type="hidden" name="id" value="<%=id%>" />
    </c:when>
    <c:otherwise>
        <br/>
    </c:otherwise>
</c:choose>

The problem is that this code displays <br /> when id is null or non null (add and edit) … And I don’t see why it doesn’t work.

Thanks for your help,

S

Answer 1

The problem is that your variable id is not in a scope which jstl can reach.
You need to do:

pageContext.setAttribute("id", id);

Also, it’s better to test against empty:

<c:when test = "${!empty id}">

And lastly, you should use jstl when outputting the value of id:

<input type="hidden" name="id" value="${id}" />