Jeremy JGR. Grumbach wrote:
Thanks also for the answer,
I'm using Velocity so no problem with the null values.
And yes that's a way to manage exceptions, but I as said in my previous
post, I was looking for something more generic, without specific code in
all my actions.
If you want a generic exception handling solution I'd look at two things:
1) AOP using Spring
2) The S2 Exception interceptor
Spring AOP can be configured to give advice to all your actions.
Basically the advice just catches exceptions and then returns a result
code. That keeps any exception handling code out of your action. The
advice can be as complex as you want it to be. This is a bit
disadvantageous in that it's not S2 specific so you end up working
harder to do things like add error messages to the Action's error maps.
The S2 Exception interceptor (and the exception configuration that goes
along with it) give you an S2-specific way to implement a basically the
same thing: a generic fault barrier at the action-layer.
It's documented here:
http://struts.apache.org/2.0.11/docs/exception-configuration.html
If that specific interceptor doesn't do what you want, I suspect that a
modestly customized version of its code will.
But none of that does what (I thought) you were originally asking which
was to preserve the contents of the submitted form data "automatically"
between a processing action and a view action.
Doing that in a generic fashion takes a little more work since the
form-data that needs to be preserved is different depending on the
view/process actions involved (sometimes the user is entering a NewCar,
sometimes they're entering a NewCustomer).
I suppose you could come up with a generic interface (like
"SubmittedFormData") that would give your customized exception
interceptor something to work with.
For example:
In ProcessForm.action
---------------------
1) your custom exception interceptor catches any exceptions thrown below
the action and that have propagated up to the action. This is your
fault barrier.
2) your custom exception interceptor looks for an object in the action
that implements "SubmittedFormData". If it finds it, it adds that
object to the session.
3) your custom exception interceptor then does anything else appropriate
(like add errors to the Action).
4) your custom exception interceptor returns the result code of your
choice (probably INPUT in your case)
In ViewForm.action
------------------
1) You custom interceptor retrieves any "SubmittedFormData" object from
the session and pushes it onto the stack.
2) It then shows the view
And then in your view you can reference specific properties of the
SubmittedFormData object, regardles of what kind of object it actually
is (NewCar, NewCustomer, etc).
The only thing that has to know the *actual* object type is your view
code that references real properties of the SubmittedFormData object.
Everything else (the interceptor, the session storage/retrieval code,
etc.) else just works with a "SubmittedFormData" object.
----
I still feel like I'm missing something here. Is the above more of what
you had in mind?
- Gary
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