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Posted to user@struts.apache.org by Antonio Petrelli <an...@gmail.com> on 2007/11/04 17:17:25 UTC

[OT] Re: EL expressions and string concatenation

2007/11/4, Adam Hardy <ah...@cyberspaceroad.com>:
> I want to concatenate 2 vars into a string in EL but since one is a Long, EL
> can't do it, and throws a NumberFormatException because it wants them both to be
> Longs so it can do arithmetic addition instead.

You could set a string variable this way:
<c:set var="myStringVariable"><c:out value="${category.id}"/></c:set>

Antonio

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Re: [OT] EL expressions and string concatenation

Posted by Adam Hardy <ah...@cyberspaceroad.com>.
Antonio Petrelli on 05/11/07 08:14, wrote:
> 2007/11/4, Adam Hardy <ah...@cyberspaceroad.com>:
>> Antonio Petrelli on 04/11/07 16:17, wrote:
>>> 2007/11/4, Adam Hardy <ah...@cyberspaceroad.com>:
>>>> I want to concatenate 2 vars into a string in EL but since one is a
>> Long, EL
>>>> can't do it, and throws a NumberFormatException because it wants them
>> both to be
>>>> Longs so it can do arithmetic addition instead.
>>> You could set a string variable this way:
>>> <c:set var="myStringVariable"><c:out value="${category.id}"/></c:set>
>> That's not quite the minimalist approach I was thinking of, but it is one
>> approach.
> 
> 
> 
> Anyway I wonder what does it prevent you from using <c:url> and <c:param>...

To keep the JSP short and clear. Instead of these tags:

<c:url value="edit.html" var="url1">
   <c:param name="category.id">${category.id}</c:param>
</c:url>
<a href="${url1}">xxxxx......</a>

do it with JSTL-EL:

<a href="${pc:url(pc:concat('edit.html?category.id=', category.id))}">


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Re: [OT] EL expressions and string concatenation

Posted by Antonio Petrelli <an...@gmail.com>.
2007/11/4, Adam Hardy <ah...@cyberspaceroad.com>:
>
> Antonio Petrelli on 04/11/07 16:17, wrote:
> > 2007/11/4, Adam Hardy <ah...@cyberspaceroad.com>:
> >> I want to concatenate 2 vars into a string in EL but since one is a
> Long, EL
> >> can't do it, and throws a NumberFormatException because it wants them
> both to be
> >> Longs so it can do arithmetic addition instead.
> >
> > You could set a string variable this way:
> > <c:set var="myStringVariable"><c:out value="${category.id}"/></c:set>
>
> That's not quite the minimalist approach I was thinking of, but it is one
> approach.



Anyway I wonder what does it prevent you from using <c:url> and <c:param>...

Antonio

Re: [OT] EL expressions and string concatenation

Posted by Adam Hardy <ah...@cyberspaceroad.com>.
Antonio Petrelli on 04/11/07 16:17, wrote:
> 2007/11/4, Adam Hardy <ah...@cyberspaceroad.com>:
>> I want to concatenate 2 vars into a string in EL but since one is a Long, EL
>> can't do it, and throws a NumberFormatException because it wants them both to be
>> Longs so it can do arithmetic addition instead.
> 
> You could set a string variable this way:
> <c:set var="myStringVariable"><c:out value="${category.id}"/></c:set>

That's not quite the minimalist approach I was thinking of, but it is one approach.

Another approach which saves that whole line is to write another taglib function 
and use it like this:


<a href="${pc:url(pc:concat('/category/edit.html?id=', category.id))}">


where pc: is my taglibrary, but I'd like to avoid a proliferation of these 
taglib functions in my app.


regards
Adam

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