multiple instances of one ActionForm

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multiple instances of one ActionForm
7 answers - 931 bytes -
Hi!
Is there any standard ways to manage multiple
instances of one form with Struts? I have application
which is supposed to take theorerically unlimited
number of person's descriptions. Every time user
clicks "add one more person" he/she gets exactly the
same form (with the same validation rules) to fill. At
the end user clicks "finish" and all data is saved.
I'm sure this is quite common task. So far I can't see
any mechanism in Struts supporting multiple instances.
And if I manage instances manually in Action class I
loose some built-in functionality, like forms
prepopulation. Any hints/ideas?
Cheers,
Leo
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No.1 | | 1191 bytes | |
If you need to save document from Microsoft Word, you open "File Save"
dialog. When you need to save another file, do you create another
"File Save" dialog? Do all these dialogs remain allocated until you
shut down the system?

ActionForm is not a business object.

Michael.

8/8/05, Leo Asanov <leonidasanov (AT) yahoo (DOT) comwrote:
Hi!

Is there any standard ways to manage multiple
instances of one form with Struts? I have application
which is supposed to take theorerically unlimited
number of person's descriptions. Every time user
clicks "add one more person" he/she gets exactly the
same form (with the same validation rules) to fill. At
the end user clicks "finish" and all data is saved.
I'm sure this is quite common task. So far I can't see
any mechanism in Struts supporting multiple instances.
And if I manage instances manually in Action class I
loose some built-in functionality, like forms
prepopulation. Any hints/ideas?

To unsubscribe, e-mail: user-unsubscribe (AT) struts (DOT) apache.org
For additional commands, e-mail: user-help (AT) struts (DOT) apache.org
No.2 | | 1374 bytes | |
8/8/05, Leo Asanov <leonidasanov (AT) yahoo (DOT) comwrote:
Michael,

I don't see the analogy with "Save As" dialog. And
ActionForm is not a businees object indeed. Don't know
what to do with this valuable information though

If there is nothing in Struts which can help me then
it is the information I am looking for.
Although I would appreciate any ideas on application
design for my case. Lets consider a simple example -
multi-formed survey.
Form 1: Person's details
Form 2: Person's address details
Form 3: Is there any relatives?
Form 4: Relative's details
Form 5: Is there any more relatives?
If "yes" - go to Form 4.

Form 6: Some other details
Form 7: Finish a survey

What options do I have? I could manually process forms
in Form4 Action class and save instances in session,
for example, but then "Back" wouldn't work as
expected.

I see. I misunderstood you.

Why do you think you need multiple action forms? You can use one
action form with session scope, and nested beans for each html form.
For relatives' details you would have arraylist or a map.

Michael.

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No.3 | | 1262 bytes | |
Leo Asanov wrote:
Is there any standard ways to manage multiple
instances of one form with Struts? I have application
which is supposed to take theorerically unlimited
number of person's descriptions. Every time user
clicks "add one more person" he/she gets exactly the
same form (with the same validation rules) to fill. At
the end user clicks "finish" and all data is saved.
I'm sure this is quite common task. So far I can't see
any mechanism in Struts supporting multiple instances.
And if I manage instances manually in Action class I
loose some built-in functionality, like forms
prepopulation. Any hints/ideas?

Do you mean multiple instances of the same form on the same page? If so you
can use a single form with all the people's details. If you use nested
properties in your form bean you can easily keep each person's data
separated out.

If you just want to have your 'add one more person' button display a page
with a form to enter that person's details (i.e. multiple instances of the
same form being used one per request) you don't need to do anything special
besides make sure your form bean implements reset() appropriately.

L.
No.4 | | 1411 bytes | |
ActionForm does not have to correlate to HTML form one-to-one. You can
create one ActionForm with session scope and use nested DT/B for
each HTML form. For relatives' form you can use a list of nested DT
It is even simpler that you do not need to render a particular
relative, you just enter them.

Michael.

8/9/05, Leo Asanov <leonidasanov (AT) yahoo (DOT) comwrote:
Yes, I am talking about one form per request
situation. I don't really see how I can use it as it
is. ActionForm object will be overriden with the
latest one and all previous data will be lost.

Ideally I would prefer to have all data stored in the
session automatically and only when user clicks
"finish" I would take all ActionForm objects from the
session and save them into database. Without multiple
instances of one form it can easily be done.

Cheers,
Leo

If you just want to have your 'add one more person'
button display a page
with a form to enter that person's details (i.e.
multiple instances of the
same form being used one per request) you don't need
to do anything special
besides make sure your form bean implements reset()
appropriately.

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No.5 | | 1240 bytes | |
You may lose *automatic* validation remember that there is no technical
reason you have to use ActionForms at all, and if you do use them there is
nothing that says you have to associate them with Action Mappings.

For instance, I have seen some situations where developers didn't want the
auto-population to occur for one reason or another, and this is something
that cannot currently be disabled. So, they wound up doing something like
this in their Actions:

MyActionForm af = new MyActionForm();
RequestUtils.populate(af, request);
ActionErrors errors = af.validate();
if (errors != null && !errors.isEmpty()) {
request.setAttribute(Globals.ERRR_KEY, errors);
return mapping.findForward("validationFailed");
}

You could do the same if you wanted multiple ActionForms per page you
can instantiate as many as you want and deal with them manually like this.

The only "catch" is that the taglibs expect a single ActionForm per page
that is under a specific key in request. There is nothing to stop you
from putting other ActionForms in request under different keys, but only
one can be The True ActionForm per se, the rest you will have to deal
with manually.
No.6 | | 1045 bytes | |
Could you just put all of your completed ActionForms in a
session-scoped collection, then loop through that collection when the
user clicks "Finish"? This isn't a standard procedure, to my
knowledge, but it would be the first approach I would take given
similar requirements.
-- Jeff

8/10/05, Leo Asanov <leonidasanov (AT) yahoo (DOT) comwrote:
Yes, I am talking about one form per request
situation. I don't really see how I can use it as it
is. ActionForm object will be overriden with the
latest one and all previous data will be lost.

Ideally I would prefer to have all data stored in the
session automatically and only when user clicks
"finish" I would take all ActionForm objects from the
session and save them into database. Without multiple
instances of one form it can easily be done.

Cheers,
Leo

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No.7 | | 1058 bytes | |
8/10/05, Leo Asanov <leonidasanov (AT) yahoo (DOT) comwrote:
That's the first thing I thought of. But in that case
you loose "Back" function (and maybe something else as
well).

Do you need it?

You could do something if user presses "back"
on the page, but you can't do much if he clicks "back"
in the browser unless you write your own request
handler.

Back/Forward navigates between resources. Resource is an Action, not a
JSP nor an ActionForm. So, to use default Back/Forward functionality
you need to define as many action mappings as you have "navigatiable"
pages. For each action mapping you can have own actionform.

, conversely, you can serve all content from one action, in this
case you can prevent a user to use Back button at all, if you use
redirection and all your GET requests are the same.

Michael.

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