Hi,
In search of best practice for an "edit" page, here's my 3rd attempt.
It's looking pretty clean-cut to me, but I'm looking for suggestions
on how to improve it further.
private Long _personId;
@Persist("client")
// Persistence is needed here because this is a detached Entity
Bean. When we call the service to
// accept our changes, it will need its id and version fields intact
to be able to do optimistic
// locking check and a successful merge. "client" is used so that
even if you use the Back button
// to get to this page, we will have the right Person object.
private Person _person;
void onActivate(Long id) throws Exception { _personId = id; }
Long onPassivate() { return _person.getId(); }
void setupRender() throws Exception {
if (!_form.getHasErrors()) {
_person = getPersonService().findPerson(_personId);
}
}
void onValidate() throws Exception {
if (...a bit of validation logic detects an error...) {
_form.recordError(...);
}
}
Object onSuccess() {
try {
getPersonService().changePerson(_person);
_nextPage.onActivate(_personId);
return _nextPage;
}
catch (Exception e) {
_form.recordError(ExceptionUtil.getRootCause(e));
return null;
}
}
void cleanupRender() {
_form.clearErrors();
}
Some notes:
1. Detached object - Person is a detached entity. I am deliberately
avoiding refreshing it every time in setupRender() because a) it would
overwrite the user's changes, and b) it would defeat optimistic
locking: if someone else has changed the object then I DO want
getPersonService().changePerson(_person) to reject the transaction
when Save is pressed.
2. Thread-safety - I'm using "client" persistence to avoid the whole
thread-safety issue caused by the user opening a new window or tabs in
same browser (T5 can't tell them apart so they share the same
HttpSession).
3. onPrepareFromForm() - I'm avoiding it because it gets called too
often (something to do with "rewind"?). setupRender() seems better
for the job. Any downside t this?
4. cleanupRender() - if/when 5.0.7 uses flash persistence on the
form's ValidationTracker then I'll ditch this method.
Suggestions please!
Thanks,
Geoff
