Object itself could be such a buffer (or rather working copy of an object) and later it can be merged with Hibernate session /session.merge() / when necessary
For the comparison fairness I simply pointed to the fact that Struts does not require all the object fieds to be duplicated in ActionForm as people often do. James Carman <[EMAIL PROTECTED]> wrote: This is exactly what they're trying to avoid, putting "business objects" into their page logic. The problem with that, as pointed out earlier, is that it can leave your business objects in an invalid state (they have an identifier assigned to them, but the record isn't actually in the database). So, they're trying to come up with a "buffer" to avoid such a situation. -----Original Message----- From: Konstantin Iignatyev [mailto:[EMAIL PROTECTED] Sent: Wednesday, May 03, 2006 1:38 AM To: Tapestry users Subject: Re: Insert/Update pages and Hibernate 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/i mg19.html http://sandbox.sourcelabs.com/kosta/sashstarter-2.0/docs/presentation/html/i mg20.html http://sandbox.sourcelabs.com/kosta/sashstarter-2.0/docs/presentation/html/i mg21.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 > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > > -- 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) --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
