[Webwork-user] I18n and more

[Rickard O. <ri...@jb...>]

Hey

Following Edwins advice I have begun converting the JavaWorld article on
i18n to WebWork. It is pretty straightforward, aside from the fact that the
original really is *JSP* with all that comes with that *shiver*. So, a bit
of "shaping up" has been done, which made it easier to read, but also a
little bigger in terms of number of classes.

Nevertheless, it was fairly easy to do so, and I'm very glad I did it
because it showed two things that are missing from WebWork. Two tags to be
precise.

First of all, currently generic components are now done as small
jsp:included JSP's which are customized with parameters. They all have a
"label" parameter which denotes the label of the component. The problem is
that it is not possible to have dynamic content for the label in any easy
way. The reason is the way it is supplied, which is as a jsp:param.
jsp:param has an attribute "value" which has a runtimeexpression as value.
This does indeed allow for extraction of dynamic content for the value, but
it would be nicer to be able to use WebWork properties.

I.e. instead of:
<jsp:param name="label"
value="<%=((SomeAction)pageContext.getAttribute("result")).getTexts().getStr
ing("somefield.label")%>"/>
I would want to do:
<jsp:param name="label"><webwork:property
name="texts:somefield.label"/></jsp:param>
i.e. let the body of the param tag be its value.

This is not how jsp:param works, but I have already created a webwork:param
which works like the way I want it to for the URL tag. What I will do now is
to adapt it to also work with a new webwork:include tag, which will be a
replacement for jsp:include. By doing this we can i18n'alize components'
labels much easier. I hope you see how by the above.

The second thing that is needed is a "quick action" for formatting output.
The Actions in WebWork are somewhat coarsegrained and are used for either
page or component processing. However, in the i18n example there is a place
where a currency is converted to another currency, and the currency name is
appended. E.g. $1 is converted into 8.93 SEK. This kind of field-by-field
processing is a bit cumbersome to do as Actions. I have actually done that
with this particular example, and it looked something like this:
<jsp:include page="i18n.ConvertPrice?result=price.jsp" flush="true>
   <jsp:param name="price" value="1"/>
</jsp:param>
where price.jsp is:
<taglib ...>
<webwork:property name="realPrice"/>

So, all that happens in ConvertPrice is that a conversion to a given locales
currency is done. To use actions and includes for this is somewhat awkward
and obscure.

Here's is a suggestion for an alternative solution. Introduce a tag "action"
which takes an action name as parameter, and which is executed as usual, but
its result from execute() is ignored and instead the action is made
available (for use by the property tag, for example) during the execution of
its body. Like this:
<webwork:action name="i18n.ConvertPrice">
  <webwork:param name="price"><webwork:property name="cd:price"/>
  <!-- at this point the ConvertPrice action has been instantiated, its
setPrice method has been called, and execute() has also been called -->
  <webwork:property name="realPrice/> <!-- call getRealPrice on action to
print out the converted price including currency type indication -->
</webwork:action>

This would allow the MVC paradigm to be preserved, but allow for much more
lightweight usage than the usual action->jsp model. The above is somewhat
flawed still (how to determine when to call execute(), what happens if
execute() wants to show some error view, etc.) so if you have any ideas on
the above, speak up :-)

regards.
  Rickard