I think the Barracuda project has done things in this area
http://barracuda.enhydra.org/
I am currently beginning to implement struts and have also been reading
about the alternatives. Each is developing in its own direction. I like
the Barracuda design. It is more OO and does not rely on jsp.
----- Original Message -----
From: "Ted Husted" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Friday, June 01, 2001 9:46 AM
Subject: Re: Proposed feature: Bean property transformations
> What I'm missing is a comprehensive, general package for converting data
> types and formatting properties for presentation. Most of this
> functionality is available somewhere in java and javax space, but it's
> spread around.
>
> What would be most useful, I think, is a single, generic package that
> provided
>
> (1) validation of Strings using regular expressions (a la David
> Winterfeldt's servlet), with direct support for native and JDBC
> datatypes,
>
> (2) binary to String and String to binary conversions for all native and
> standard types, and support for adding others,
>
> (3) given a formatting specification ("00#.##") and data of any
> supported type, return a formatted presentation String,
>
> (4) support for locale-senstive transformations with (3),
>
> (5) support for extending the formatting specification for unusual
> circumstances, and
>
> (6) provide simple date-calculation methods and a countdown presentation
> format (seconds, minutes, hours, or days from now until then).
>
> We could then use this helper object during the validation cycle to
> convert incoming Strings to the other types needed by business-logic
> objects, AND pass through the functionality from a <bean:writeTransform
> > tag, that could pull a property from a given bean, transform it, and
return a formatted String for direct use by the view.
>
> If there is not something like this already out there, I've very
> interested in getting started on this package, since I really, really
> need it for my own projects. Could be a nice addition to the Commons ...
>
> I'm cross-posting this to Struts user in case someone can suggest a
> package that already provides this functionality.
>
> -- Ted Husted, Husted dot Com, Fairport NY USA.
> -- Custom Software ~ Technical Services.
> -- Tel 716 737-3463.
> -- http://www.husted.com/about/struts/
>
>
> Ron Smith wrote:
> >
> > I've been thinking of implementing this feature lately and I haven't
> > seen it proposed on this list yet. Any comments?
> >
> > Summary:
> > Provide a means to flexibly plug in transformations that could
> > be applied to JavaBean properties for presentation in a JSP page.
> > What transformation to apply to which JavaBean property
> > is specified in the Struts JSP tags (e.g. bean:write).
> > Transformations are Java classes that are responsible for taking
> > a JavaBean property or any other Object, applying whatever
> > transformation, and returning the transformed Object for
> > presentation in a JSP page.
> > Some example transformations are to format a date in a specific
> > format, format decimal numbers, or even to sort a collection in
> > a particular order before iterating over the collection's objects.
> >
> > Motivation:
> > Separating business entity code from presentation-specific code
> > is a good thing. Consider a business entity class called Order. If
> > we want to display the orderPlacedDate attribute in 4 different
> > date formats on a JSP page, we could add 4 different methods to
> > the Order class to support these 4 different formats. But we quickly
> > end up with a very cluttered Order class and the Order class is too
> > coupled to the presentation details.
> > One approach I've used is to create presentation wrapper classes
> > which hold references to the business entity objects and are
> > responsible for all of the presentation specific formatting. The
> > JSP pages access the presentation wrapper classes and not the business
> > entity classes. For sites that access many different business entity
> > classes, this can become very tedious.
> > A better approach would be to be able to plug-in specific types of
> > presentation transformations to be applied to specific JavaBean
> > properties that are to be displayed in a JSP page without having to
> > create unecessary wrapper classes.
> >
> > Details:
> > Transformations are coded in transformation classes, all of which
> > implement
> > a Transformation interface. This interface has one public method:
> > Object transform(Object inObj)
> > This method is responsible for applying whatever transformation is
> > needed
> > to the passed in object and returning a transformed version of the
> > object for presentation in a JSP page.
> > The transformation objects would be created at initialization based on
> > the
> > configuration file, and could be initialized with some parameters from
> > the
> > configuration file (e.g. the date format string to be used for a date
> > transformation). Each transformation has a name associated with it, and
> > is
> > registered in a hash table based on the name.
> >
> > Some of the Struts custom JSP tags would be modified to take an
> > additional
> > transformation parameter which indicates what transformation is to be
> > applied. For example:
> > <bean:write name="order" property="orderPlacedDate"
> > transformation="shortDateFormat"/>
> > In the above example, the orderPlacedDate property is retrieved
> > from the order bean, then the Transformation named "shortDateFormat"
> > is looked up in the transformations registry, and applied to the
> > property. Whatever was returned by the transformation is what gets
> > displayed on the web page.
> >
> > Another benefit is that because the transformation objects exist
> > throughout the life of the application, some objects such as DateFormat
> > and NumberFormat can be cached in the transformation objects for
> > efficiency purposes.
> >
> > There's more details, but that's the basic idea.
> >
> > Ron
>
