First of all thanks a lot for the good and well structured reply. I tried
<s:set name="a" value="%{'/jsp/'+#parameters.file.toString()}" />
but the result is still the same. I also wrote an own static method that
prints out the result and it is also "/jsp/[Ljava.lang.String;@1bd2184".
However, a static concatenation method will most probably work, but I
hope it is not the only way to do it.
In JIRA I only found a three year old issue asking for the concatenation
via "+" in the property tag. I cannot imagine String concatenation not
being supported. I am going to create a JIRA issue for that tomorrow,
unless someone can tell me another way than using a static concatenation
method.
Best,
Anton
Jeromy Evans wrote:
> I don't have the full solution, but lets think about this for a moment
> instead of using trial-and-error...
>
> By default, every struts2 tag either expects the attribute to be a
> string literal, an OGNL expression evaluated as a string or an OGNL
> expression evaluated as an object. We don't really know which without
> checking the docs or code, but as we're performing an operation we can
> take the safe path state that we're using an OGNL expression.
>
> <s:set name="a" value="%{insert_expression}" />
>
> Now that we know we're using an expression we discount all the attempts
> that aren't valid OGNL and write some OGNL to concatenate a string
>
> <s:set name="a" value="%{'/jsp/'+#parameters.file}" />
>
> ie. a string literal concatenated to the root object parameters' member
> named file
>
> You said you tried this and got:
>
> "/jsp/[Ljava.lang.String;@1bd2184"
>
> The concatenation has worked, but it evaluated #parameters.file as an
> object reference rather than a string. Now you've isolated the problem
> to this sub-expression. That sucks, so now think of a way to instruct it
> that we want to value to be evaluated as a string.
>
> Does <s:set name="a" value="%{#parameters.file}" /> work? It should, so
> the problem is specific to the concatenation operation.
>
> Maybe we need to force evaluation of a string prior to concatenation
> (haven't tried this:)
>
> <s:set name="a" value="%{'/jsp/'+#parameters.file.toString()}" />
>
> ie. call toString() prior to concatentation. One of two things will
> happen: it will work because the result is strongly-type as a string, or
> it will concatenate another reference to a string object
>
> If that doesn't work, at this stage I'd search JIRA for a known problem
> and resort to something more reliable like calling a static method
>
> <s:set name="a" value="[EMAIL PROTECTED]@concatenate('/jsp/',
> #parameters.file)}" />
>
> Hope that helps,
> Jeromy Evans
>
> PS: s:text evaluates the name attribute as a string,whereas s:set
> evaluates the value attribute as an object. This accounts for the
> different behaviour. I find this inconsistency between tags is one of
> the most frustrating aspects of how OGNL is used by struts2.
>
> Anton Pussep wrote:
>> Results in the same as
>>
>> <s:set name="a" value="'/jsp/'#parameters.file" />
>>
>> which means that a remains unset.
>>
>> Same for:
>>
>> <s:set name="a" value="/jsp/%{#parameters.file}" />
>> <s:set name="a" value="'/jsp/'%{#parameters.file}" />
>> <s:set name="a" value="%{/jsp/#parameters.file}" />
>> <s:set name="a" value="%{'/jsp/'#parameters.file}" />
>>
>> Best,
>> Anton
>>
>> Saul Qunming Yuan wrote:
>>
>>> Hi
>>>
>>> You may want to try the following to set variable "a":
>>>
>>> <s:set name="a">
>>> <s:text name="/jsp/%{#parameters.file}" />
>>> </s:set>
>>>
>>> just a thought.
>>>
>>> Saul
>>>
>>> Anton Pussep wrote:
>>>
>>>> Hello,
>>>>
>>>> I am trying to concatenate strings in tag attributes and get results
>>>> that I don't understand:
>>>>
>>>> <s:text name="/jsp/%{#parameters.file}" />
>>>>
>>>> prints out "/jsp/test.jsp", whereas
>>>>
>>>> <s:set name="a" value="'/jsp/' + #parameters.file" />
>>>> <s:text name="#a" />
>>>>
>>>> prints out "/jsp/[Ljava.lang.String;@1bd2184", same for
>>>>
>>>> <s:set name="a" value="%{'/jsp/' + #parameters.file}" />
>>>>
>>>> whereas the following does not work:
>>>>
>>>> <s:set name="a" value="'/jsp/'#parameters.file" />
>>>>
>>>> What is the way to concatenate strings in the set tag and why
>>>> doesn't it
>>>> work the same way as it does in the text tag?
>>>>
>>>> Best,
>>>> Anton
>>>>
>>>>
>>>>
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