FYI: there is no need to 'maintain' ActionForm in Struts unless you
need to, this is the common mistake.
Business object can be placed in the ActionForm as one field and its
properties accessed and set in OGNL like fashion
via BeanUtils.
http://sandbox.sourcelabs.com/kosta/sashstarter-2.0/docs/presentation/html/img19.html
http://sandbox.sourcelabs.com/kosta/sashstarter-2.0/docs/presentation/html/img20.html
http://sandbox.sourcelabs.com/kosta/sashstarter-2.0/docs/presentation/html/img21.html
It is even easier with Struts' "nested" taglib
Jim Steinberger wrote:
Paul, thanks a lot for your insight; I'm finding it very very helpful.
The only thing I'm really not excited about with this approach is the
number of times my domain-properties are going to be repeated throughout
my page classes and/or value-objects.
After struggling to maintain Struts ActionForms in the face of
domain-changes, seeing how HTML forms can be tied directly to
domain-objects via OGNL in Tapestry was a big selling point behind
getting me to switch.
I'm just pouting, though -- I appreciate the necessity of a data-buffer
at the UI level, particularly when dealing with a persistence mechanism
that can potentially leave objects in an indeterminate state.
Thanks again,
Jim
-----Original Message-----
From: Paul Cantrell [mailto:[EMAIL PROTECTED]
Sent: Tuesday, May 02, 2006 10:09 PM
To: Tapestry users
Subject: Re: Insert/Update pages and Hibernate
Jim --
My suggestion would be to keep all the user-entered values around in
an object that's not the manufacturer, but is solely a value object
that is very specific to this particular UI. In most cases, this is
the page class itself:
class CreateEditManufacturer extends BasePage {
public abstract get/setName();
public abstract get/setFlavor();
public abstract get/setBossesFavoriteMarxBrother();
...etc...
public IPage saveManufacturer() {
try {
getManufacturer().setName(getName());
getManufacturer().setBossesFavoriteMarxBrother
(getBossesFavoriteMarxBrother());
...etc...
getManufacturerService().createManufacturer();
} catch (Exception e) {
setError("Could not create Manufacturer: " + e.getMessage());
return this;
}
}
}
But perhaps you have a multi-page process or something, where it
becomes simpler to build up the user's responses in a _value object_:
class CreateEditManufacturer extends BasePage {
@Persist("server")
public abstract ManufacturerEntryForm get/
setManufacturerEntryForm();
public IPage saveManufacturer() {
try {
values = getManufacturerValues();
getManufacturer().setName(values.getName());
getManufacturer().setBossesFavoriteMarxBrother
(values.getBossesFavoriteMarxBrother());
...etc...
getManufacturerService().createManufacturer();
} catch (Exception e) {
setError("Could not create Manufacturer: " + e.getMessage());
return this;
}
}
}
class ManufacturerEntryForm implements Serializable { // *not*
persistable!
...
}
Either way, the point is that you keep the user's input in a value
object of some kind, page or otherwise, that is -- this is the key --
modeled after the user interface, *not* after the domain object. The
value object is a transcription of what the user entered.
Only when you're ready to do something committable do you apply
changes from the UI to the domain. So you're not cloning the domain
object; you're just not eagerly applying changes to the domain at
each step.
This is not an "always the right answer" practice; it's just a
"usually works best" practice.
But yes, in any case, you're quite right: Hibernate doesn't do any
kind of in-memory rollback on your objects! No matter what approach
you take, you *cannot* manipulate a domain object unless you're
prepared to either (1) commit it or (2) discard it.
Cheers,
Paul
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--
Thanks,
Konstantin Ignatyev
http://www.kgionline.com
PS: If this is a typical day on planet earth, humans will add fifteen million
tons of carbon to the atmosphere, destroy 115 square miles of tropical
rainforest, create seventy-two miles of desert, eliminate between forty to one
hundred species, erode seventy-one million tons of topsoil, add 2.700 tons of
CFCs to the stratosphere, and increase their population by 263.000
Bowers, C.A. The Culture of Denial:
Why the Environmental Movement Needs a Strategy for Reforming Universities and Public Schools.
New York: State University of New York Press, 1997: (4) (5) (p.206)
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