@Persist("flash")
http://tapestry.apache.org/tapestry5/tapestry-core/guide/persist.html
and, since I can peddle my own wares
@Persist("flashcookie")
http://wiki.apache.org/tapestry/Tapestry5HowToUsePersistentFieldStrategy
I've had one (or two) too many glasses of wine. May your night be as good as
mine :)
--nK
On Tue, Apr 22, 2008 at 9:54 PM, Christoph Jäger <
[EMAIL PROTECTED]> wrote:
> Hi,
>
> Sorry for this long post. I spent quite some time now to try to figure out
> how to use forms to edit/update objects the "right" way (you know, simple,
> stable, elegant, easy to read, easy add things, ...). I use Tapestry
> 5.0.11. I am almost satisfied with what I came up with now, but some
> improvements need to be done. Maybe someone on this list can help with some
> ideas.
>
> As an example, lets have a PersonEdit page, with a PersonDao injected. You
> can create new Person entries or edit existing ones. To edit an existing
> person, there is a PageLink on a PersonSearch page, which has the Person's
> primary id as context. To create a new Person, a PageLink with 0 as context
> is used. To make this work, we have onActivate() and onPassivate() methods
> in PersonEdit:
>
> void onActivate(int id)
> {
> _id = id;
> if (id == 0)
> {
> _person = new Person();
> }
> else
> {
> _person=personDao.get(id);
> }
> }
>
> int onPassivate()
> {
> return _id;
> }
>
> This way we can avoid using @Persist on the Person property (because, for
> instance, we want a user to be able to open two browser windows, viewing two
> different Person entries side by side and edit and save both of them. I
> think this would be problematic if we use @Persist, but please correct me if
> I am wrong).
>
> Now, editing an existing user works like this:
>
> - click the "edit user XYZ" PageLink on the PersonSearch page
> - in onActivate(), the personDao is used to query the Person from the
> database
> - an HTML form is rendered to let the user edit the values
>
> Up to here everything looks perfect.
>
> - the user edits the Person's data and hits the "save" button
>
> - onActivate() is called, a fresh Person is loaded from the database
> - for each field in the HTML form, validation is done (if defined), and a
> property in the fresh Person instance is set if the validation was
> successful
> - onValidateForm() is called if existing to allow for cross-field
> validation
> - if all validations were successful, onSuccess() is called. Here we call
> _person=personDao.save(_person). This save method returns a new Person
> instance, exactly as it was written to the database (primary id may be
> generated by the database, time stamps or version numbers updated, ...). We
> use this new Person's id : _id=_person.getId() to make sure we have the
> correct if for the next onPassivate()
> - onPassivate() is called
> - result sent to browser, redirect
> - onActivate() loads Person again
> - new form is rendered
>
> This is good, but I think it could be improved.
>
> 1. The Person is loaded from the database twice (using personDao.get()),
> and saved once. The save() method of personDao already gives us a new, fresh
> instance of Person, it seems like a waste to load it again after the
> redirect.
>
> 2. During validation, we check if there is already a Person with the same
> userid (in onValidateForm(), or in onValidateFromUserId()) and warn the user
> if this is the case. But what happens if a new Person with this userId is
> added just after onValidateForm() is called, but before onSuccess() is
> called, where we want to save? To make our program solid, we have to take
> this into account. In case save() does not work, we do not want to see some
> exception page, but the form, as it was filled, with a hint what might have
> gone wrong, so the user can try again. To make this possible, we have to
> move the save() to onValidateForm(), because there we can still record form
> errors (I think there is a JIRA for an improvement to this situation).
>
> 3. We want to give the user feedback of what happened. After clicking the
> save button, we want to show a message like "Successfully saved new person
> information" above the form (at the same place you would see error messages
> like: "The first name is mandatory"). The only thing that comes to my mind
> is to use @Persist to save the message from the onSuccess() or
> onValidateForm() through the redirect to the next page render. But now I
> have problems to make sure this @Persist'ed message is cleared and is only
> presented to the user directly after the save button was clicked.
>
>
> I think to find a nice solution for these issues (you know, easy things
> should be easy to do, and a form like this does not sound very complex to
> me, so there should be an easy solution), a @Persist, which persists values
> just through the redirect would be very helpful. The problem is, I have no
> idea how this could work. But maybe an option like this already exists (I am
> sure I am not the first to have problems like this), and I just didn't find
> it.
>
> Any ideas are welcome,
>
> Thanks,
>
> Christoph Jäger
>
>
>
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