Re: AW: AW: using multiple action forms in one action. Best practice?

[Bill Keese]

It's hard for me to answer because I don't really understand your 
application.  JSP1 is for picking a region, and then JSP2 is for picking 
stores within that region, right? And then after picking the stores, you 
display a confirmation page with the map and the list of picked stores?

When you hit the "save" button on the confirmation page, the input to 
the SaveAction is both the selected region and the selected stores, 
right?  So you are combining the information entered on two previous forms.

If it was me, I would have 3 separate actions and 3 separate action-forms:
  1. select-region
  2. select-stores
  3. confirm-dialog
The confirm-dialog ActionForm would contain both the region information 
and the list of stores.  Thus I would only use one ActionForm per 
Action, and I wouldn't use session variables.

Bill
Martin Kindler wrote:
Hi Bill,
so you say, it is good practice to use the two forms in one action as I do
in my current solution? Sure, one has to hide the internals from AF1 to an
action primarily designed to use AF2 to keep the address module generic.
Perhaps I should make the calling ActionForms implement a specific
interface.
If I really want a fully generic address module I would have to split the
action(s) in two, simply because the actions designed for the address module
need a generic API. I cannot rely (for full genericity) on a "calling"
module to use AF1. In my current situation I will probably ignore this as it
is a straightforward refactoring which can be done when need occurs. 
As to the question request vs. session scope I understand the problems which
might occur using session scope.
I do not see a solution which would also fulfil the modularization
requirement.

Thanks!
Martin
 

-----Ursprüngliche Nachricht-----
Von: Bill Keese [mailto:[EMAIL PROTECTED] 
Gesendet: Dienstag, 16. November 2004 02:10
An: Struts Users Mailing List
Betreff: Re: AW: using multiple action forms in one action. 
Best practice?

Hi Martin,
   

From this JSP I want to access a (hopefully) generic module 
     

to get the 
   

access points. This "module" has to get some information (e. g. a 
region to prefilter the addresses or access points already 
     

existing) 
   

from JSP1.
     

I think you should  generate the input to the generic module, rather 
than passing the ActionForm directly:

  // get data from ActionForm1 needed to look up addresses
  AddressLookupInfo info = getAddressInfoFromActionForm1(AF1);
  // lookup addresses
  List res = AddressLookup.getAddresses(info);
   ...
Then your module can still be generic.
   

I could take the necessary information from AF1 to some 
     

POJO (or bean) 
   

on model level (or controller level) and transfer it to 
     

AF2. This is 
   

probably the "cleanest" solution but means to split each 
     

action into 
   

two, just to do
the data transfer.
     

You shouldn't need to split each action into two.  Action1's 
job is to 
handle the input from ActionForm1, and then do the setup to display 
JSP2, right?  So, just create the ActionForm2 manually inside Action1:

 // Create AF2 as an input/output form
 ActionForm2 af2 = new ActionForm2();
 session.setAttribute("actionForm2", af2);
 // ... and pre-populate it with the data the user has already input
 ActionForm1 af1 =
          (ActionForm1) getActionForm(mapping, form, 
request, session);
 af2.loadDataFromAF1(af1);

 // forward control to JSP2
 return (mapping.findForward("jsp2"));
   

My current solution simply accesses both action forms, AF1 and AF2
(getting
the one not available as the "form"-parameter by MyForm mf = 
(MyForm)session.getAttribute("AFi");
but my feeling is that this is not really good style.

     

I guess it depends on whether you consider the two forms to represent 
one logical command or two logical commands.

The other thing to consider, though, is whether or not you 
want to store 
the ActionForms at session scope.   Session scope is 
problematic because 
you might end up accessing old data (if the user previously 
quit in the 
middle of a wizard).  Also, I imagine things would fail in a 
distributed 
application where the user's requests are randomly routed to multiple 
servers.    The alternative is to use request level scope, 
but in this 
case the information entered in Form#1 has to be embedded in 
the output 
of JSP2 as hidden HTML variables.

Bill
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