Re: Passing parameters to included JSP files

Wednesday, October 17, 2012, 10:19:23 PM, Ionut Prunache wrote:

> Yes, that's correct, I'm only seeing "param1" in both page2.jsp and
> page3.jsp. I should have mentioned that i'm using tomcat as application server.
>
> I found out why it's not working, at least for me, after some
> debugging. The problem comes from the combination of Freemarker's
> CustomParamsRequest and apache's implementation of request wrapping
> and forwarding. CustomParamsRequest is used to wrap the page's
> HttpServletRequest and pass parameters when performing an ftl
> include_page. It holds the parameters in a map separated from the
> wrapped request that it only modifies at construction time. From
> then on it never updates that map, not even if the wrapped request gets changed.
> And that's where it conflicts with apache's implementation.
> Apache's implementation does not wrap around Freemarker's 
> CustomParamsRequest wrapper when performing an include,  instead it
> just creates a new ApplicationHttpRequest, it's request wrapper, and
> replaces the request wrapped by CustomParamsRequest.

They don't create a new ServletRequestWrapper to wrap the original
request... the modify the current request. Ouch. But, the Servlet (and
JSP) sepc. is rather vague, so it's not like formally they violate
anything.

> Because CustomParamsRequest never checks that it's request changes
> and always serves it's initial parameters, any new parameters added
> by the changes are never visible.
>
> I managed to make it work by hacking  CustomParamsRequest and
> rebuilding freemarker.jar. I'm using this for now and i hope it's
> good enough until i manage to complete the transition from JSP to ftl.

So what it should do is, checking if the wrapped request was replaced,
and if it was, re-build the internal parameter map. Right?

> On Wed, Oct 17, 2012 at 7:12 PM, Daniel Dekany <[email protected]> wrote:
> Wednesday, October 17, 2012, 3:06:30 PM, Ionut Prunache wrote:
>
>> I'm working on a project for replacing an existing JSP code base
>> with Freemarker. I'm trying to do it progressively, that is I still
>> want to be able to include some JSP files from my new Freemarker templates.
>>
>> The JSP pages that I include directly from .ftl files work fine,
>> but there is a problem when a JSP page included from an ftl tries to
>> include another JSP page and pass it some parameters. The second JSP
>> file loads but doesn't receive the parameters from the calling JSP,
>> it only gets the parameters that the .ftl passed to the first JSP.
>>
>> Here is a short example of the flow:
>>
>> page1.ftl
>> ...
>> <@include_page path="/WEB-INF/jsp/page2.jsp" inherit_params=true params={"param1": "param1"}/>
>> ...
>>
>> page2.jsp
>> ...
>> <jsp:include page="/WEB-INF/page3.jsp">
>>     <jsp:param name="param2" value="${someVar}"/>
>> </jsp:include>
>> ...
>>
>> request.getParameterNames() only contains param1 for both page2.jsp
>> and page3.jsp. I expect page3.jsp to see both param1 and param2.
>
> Just to be sure, you are seeing "param1" only, in both page2.jsp and
> page3.jsp, right? (When you try that, just print them, because
> getParameterNames might have its own problems.) Then in page2.jsp, the
> jsp:include didn't add "param2" to the request. That's the jsp:include
> implementation's doing, and I don't see why it's happening. What's the
> class of the request object in page2.jsp and in page3.jsp?
>
>> Is there a way for this to work? If so, what am i doing wrong?
>>
>> Thanks
>> Ionut
>
> --
> Best regards,
>  Daniel Dekany
>
>
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-- 
Best regards,
 Daniel Dekany


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