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Posted to user@struts.apache.org by Roger Nell <ro...@yahoo.com> on 2002/03/26 17:01:59 UTC
Form processing work flow
What is the pattern for processing a form?
Given:
MyForm extends ActionForm
MyFomAction extends Action
MyForm.jsp displays the form
using Struts 1.1 beta
1. Prior to calling MyFormAction.execute(), a MyForm() object is
created by struts. In 1.0.x I would create the form object here. The
struts example app was modified to accomodate this change.
2. In MyFormAction.execute() I call the form's set methods to setup
the form's properties.
3. I save the form in the request attributes
4. The form is displayed by MyForm.jsp
5. The user hits submit button.
6. MyForm.reset() is called on a newly created MyForm().
7. MyForm set methods are called on the form in step #6
8. I see the MyForm saved to the request attributes in step #3.
9. Struts calls MyForm.execute() with the form created in step #6
The problem is that struts is not giving me back the Form object
saved in the request attributes in step #3 after the submit. Instead
I get a new form obbject that was created in step #6. I want the one
saved in the request attributes because it contains information
needed to save the form back to the database or for a multipage form.
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Re: Form processing work flow
Posted by Nicolas De Loof <ni...@cgey.com>.
Object saved to request scope are destroyed when the request is completed
(when the JSP has produced the HTML response). So you cannot get your
"saved" Form after that.
You have to put it in the session scope so that you can get it back for
future requests.
> The problem is that struts is not giving me back the Form object
> saved in the request attributes in step #3 after the submit. Instead
> I get a new form obbject that was created in step #6. I want the one
> saved in the request attributes because it contains information
> needed to save the form back to the database or for a multipage form.
>
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Movies - coverage of the 74th Academy Awards®
> http://movies.yahoo.com/
>
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> To unsubscribe, e-mail:
<ma...@jakarta.apache.org>
> For additional commands, e-mail:
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RE: Form processing work flow
Posted by Alex Paransky <al...@individualnetwork.com>.
The data you put into the request is lost after the request is finished.
When you press the submit button a new request is created, thus your newly
created MyForm is what you get in the action. There two options if you want
to keep the "old" data from the previous instance of the MyForm object:
1. Put the MyForm object into the session (you can either change the scope
on your action, or do it your self). Then, in the next action you would get
the same form you put into the request earlier. At the end of the "saving"
step, you can remove the form from the request to free up the memory.
2. Keep the form at the request scope and layout enough <input hidden fields
to "forward" the data to the next action. When the submit occurs, struts
will pick up all the fields and populate the new instance of MyForm before
giving it to you. If you need an student_id field in order to update
student information, then pass it as a hidden variable.
Both of these tend to work equally well for what you are trying to do. I
use option 1, since during the "load" stage the form is loaded with a lot
more information than is actually "directly" modified by the user. For
example, MyForm might contain a Collection of options to be used for a
dropdown list on the MyForm.jsp view. So, if you use option 2, that data
might be lost if the user makes a mistake and is reverted back to the
MyForm.jsp or MyFormAction via the struts validate(...) and input=
combination on the action.
In my development, I found that I wanted to keep the "load" and "execute" of
the form in the same action. So, I created a "custom" action which uses the
parameter= attribute to determine what to do. Then for my MyFormLoad.do and
MyFormExecute.do I use the same physical java class, but as different
actions with different options. In other words, to signal a load and keep
the form in the session I pass parameter="+load+keepForm", as a result
loadForm(...) method is called in my action. When I need to execute the
form, I pass parameter="+execute+removeForm", which performs
executeForm(...) and then removes (clears) the form from the session.
There are other methods for form control. Some of them include setting
flags in the session to indicate that a load need not be performed anymore.
Others use "immutable" form fields pattern. I have yet to find a "standard"
method that would (cleanly) accommodate:
1. Custom non trivial form loading
2. Proper form validation
3. Clean method for separating user input fields from display fields
This pattern seems to be working ok for me, so far, there are problems, such
as the input= parameter points to a .jsp page and not to a formLoad.do
(because that would re-set) the form with all user's input. Your mileage
may vary.
-------------
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-----Original Message-----
From: Roger Nell [mailto:rogernell@yahoo.com]
Sent: Tuesday, March 26, 2002 8:02 AM
To: struts-user@jakarta.apache.org
Subject: Form processing work flow
What is the pattern for processing a form?
Given:
MyForm extends ActionForm
MyFomAction extends Action
MyForm.jsp displays the form
using Struts 1.1 beta
1. Prior to calling MyFormAction.execute(), a MyForm() object is
created by struts. In 1.0.x I would create the form object here. The
struts example app was modified to accomodate this change.
2. In MyFormAction.execute() I call the form's set methods to setup
the form's properties.
3. I save the form in the request attributes
4. The form is displayed by MyForm.jsp
5. The user hits submit button.
6. MyForm.reset() is called on a newly created MyForm().
7. MyForm set methods are called on the form in step #6
8. I see the MyForm saved to the request attributes in step #3.
9. Struts calls MyForm.execute() with the form created in step #6
The problem is that struts is not giving me back the Form object
saved in the request attributes in step #3 after the submit. Instead
I get a new form obbject that was created in step #6. I want the one
saved in the request attributes because it contains information
needed to save the form back to the database or for a multipage form.
__________________________________________________
Do You Yahoo!?
Yahoo! Movies - coverage of the 74th Academy Awards.
http://movies.yahoo.com/
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<ma...@jakarta.apache.org>
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<ma...@jakarta.apache.org>
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