JSP Custom Tag and Expressions for parameters

Question

This should be an easy question. I am trying to use an expression for a
          parameter to a jsp or custom jsp tag. When I hard code a value for the
          parameter, the tag works fine but when I use the expression, the expression
          gets evaluated but the tag itself does not resulting in the tag being shown
          in my output.
          For example:
          <jsp:forward page="www.slashdot.org"/> works
          <jsp:forward page="<%=request.getParameter("DESTINATION")%>"/>
          places the following into my html output
          <jsp:forward page="www.slashdot.org"/>
          Can someone please tell me what I am doing wrong or at least offer some
          debugging hints?
          Thanks in advance!
          Jacob Meushaw
          

Answer 1

I have experienced almost this exact same problem, but with a custom
          tag. And I did make sure that my attribute specified
          <rtexprvalue>true</rtexprvalue>. Here is the weird part.
          If I do the following JSP code everything works fine:
          <% String foo = request.getParameter("bar"); %>
          <mytag:custom param="<%= foo %>"/>
          But if I do this:
          <mytag:custom param="<%= request.getParameter("bar") %>"/>
          I get the following in my html output:
          <mytag:custom param="whatever bar is set to in the request"/>
          It appears that the JSP container only does a one pass evaluation.
          Is this the spec of is this a bug?
          Jacob Meushaw wrote:
          >
          > This should be an easy question. I am trying to use an expression for a
          > parameter to a jsp or custom jsp tag. When I hard code a value for the
          > parameter, the tag works fine but when I use the expression, the expression
          > gets evaluated but the tag itself does not resulting in the tag being shown
          > in my output.
          >
          > For example:
          >
          > <jsp:forward page="www.slashdot.org"/> works
          >
          > <jsp:forward page="<%=request.getParameter("DESTINATION")%>"/>
          > places the following into my html output
          > <jsp:forward page="www.slashdot.org"/>
          >
          > Can someone please tell me what I am doing wrong or at least offer some
          > debugging hints?
          >
          > Thanks in advance!
          >
          > --
          > Jacob Meushaw
          Jeff Smith
          [email protected]
          BEA Systems, Inc.
          720-565-6613