How do I pass a parameter to a JSP via a cross-context JSTL import?

Question

I've come across a few other questions that describe a similar, but not identical situation, to mine. This question, for instance, shows pretty much the same problem, except that I'm not using portlets - I'm just using boring ol' JSP+JSTL+EL+etc.

I have two application contexts, and I'd like to import a JSP from one to the other. I know how do that:

<c:import context="/" url="/WEB-INF/jsp/foo.jsp"/>

However, I also want to pass a parameter to the imported foo.jsp. But this code:

<c:import context="/" url="/WEB-INF/jsp/foo.jsp">
    <c:param name="someAttr" value="someValue"/>
</c:import>

does not seem to properly send the parameter to foo.jsp; if foo.jsp is something like*

<% System.out.println("foo.jsp sees that someAttr is: "
                      + pageContext.findAttribute("someAttr")); %>

then this gets printed out:

foo.jsp sees that someAttr is: null

whereas I want to see this:

foo.jsp sees that someAttr is: someValue

so, obviously, someAttr can't be found in foo.jsp.

How do I fix this?

---

*(yes, I know, scriplets==bad, this is just for debugging this one problem)

Answer 1

Your context must start with a / also. Thus, in your case the code would become like this,

<c:import context="/theOtherContext" url="/WEB-INF/jsp/foo.jsp">
    <c:param name="someAttr" value="someValue"/>
</c:import>

Mind the leading slash in context name. Furthermore, try this instead.

<% System.out.println("foo.jsp sees that someAttr is: "
                      + request.getParameter("someAttr")); %>

As we are setting param not an attribute. For setting pageContext's attribute we have <c:set> but that is not the sub-tag of <c:import>. I hope you are getting my point.

One more thing to point out is, as you are trying to import a JSP page using relative URL from some other external web application in the same server. You must tell the name of the context after the /. In case, you don't want to then you should provide an absolute URL, I believe.

Answer 2

You're setting it as a request parameter, so you should also be getting it as request parameter.

Since you seem to dislike scriptlets as well, here's an EL solution:

${param.someAttr}

Note that <c:import> doesn't add any extra advantages above <jsp:include> in this particular case. It's useful whenever you want to import files from a different context or an entirely different domain, but this doesn't seem to be the case now. The following should also just have worked:

<jsp:include page="/WEB-INF/jsp/foo.jsp">
    <jsp:param name="someAttr" value="someValue" />
</jsp:include>

This way the included page has access to the same PageContext and HttpServletRequest as the main JSP. This may end up to be more useful.