--- On Tue, 6/10/08, Gamble, Wesley (WG10) <[EMAIL PROTECTED]> wrote:
> I'm not clear on the distinction between EL and OGNL.
OGNL is an EL, it's just not JSP EL.
> As a rule of thumb, would it be correct to say that OGNL is
> only valid within Struts tags, and I should never expect OGNL
> interpolation in any other context?
Yes, with the caveat that OGNL is also valid inside S2 configuration files when
surrounded by ${}, the JSP EL escapes.
(Don't ask, I don't know.)
> I thought that OGNL allowed me to get session attributes
> via the $(#session.attributeId} syntax?
Why? Is that somewhere in the S2 docs? If so, I'll fix it, because it's wrong.
${} (in the context of a JSP page) is JSP EL, evaluated by the container. "#"
is an OGNL character used to access a named value and is valid only inside OGNL
expressions... but.
But if you're running a JSP 2.1+ (2.2? I can never remember) container and
attempt to use OGNL things will blow up, because # is a JSF/JSP 2.1+ escape, so
the container tries to evaluate the following expression.
> I'm able to do what I want with this:
> <s:set name="companyId" value="#session.companyId" />
> <tiles:insertDefinition name="${companyId}_compensation" />
>
> Why does this work?
Because the first tag is using pure OGNL properly, and the second one is using
JSP EL properly, but...
> Am I using OGNL in the first line (#session.companyId) to set
> a JSP variable which I can then access in the 2nd line?
The <s:set.../> creates a variable in the stack context.
The reason the <tiles.../> works is because (a) if you already/still have a
normal JEE *scoped* variable (i.e., in session, request, etc.) it will find it
via the normal JSP EL lookup, and/or (b) S2 uses a custom request mapper that
will go to the stack context when a value isn't found in any of the normal JEE
scopes.
> The 2nd line looks like OGNL as well to me, but maybe it's EL.
It shouldn't look like OGNL.
I'd strongly recommend spending some time with the S2 docs (and potentially
some JEE docs if necessary); they should be able to clear up all these issues.
Dave
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