Jing Zhou wrote:
----- Original Message ----- From: "Rob" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, July 16, 2003 6:57 PM
Subject: dificult problem, preventing population (repost)
I have the following scenario occuring.
I have a form with several fields on it (the fields are sourced to a collection in an
ActionForm). I have a button that allows the removal of fields from the form (items
from the collection). If a user removes a field from the form and then double
submits/clicks back and reloads then an exception is thrown from BeanUtils.populate()
because it attempts to take details from the (now removed field) and populate it into
the object that is stored in the position it was located in the collection. Obviously
since the collection is now smaller this results in an IndexOutOfBoundsException.
Is there any way to examine the transaction token from the form prior to the form
bean being populated and then avoid population of the form bean if the token is not
valid?
There are three steps involved when using transaction token: 1) Setting token; 2) Checking token; 3) Resetting token;
It looks right if we could perform the second step in a subclass of the RequestProcessor so that the token is checked before form bean population. But where do we put the first step and the third step? If we put them in an action class, then how does the derived request processor know when it should check the token? If we put them all in the derived request processor, that is not correct either, because they are business logics not applicable to every action mappings.
The real *bad* guy is the browser's Back button your users
are using. The browser's tool bar and address bar are
intended to help load document oriented resources. They
are useless for application oriented resources in our
concepts. One good practice I saw is to turn off the
tool bar and address bar. It gives you the look and feel of *real* applications. Of course, you must provide navigation
buttons for your applications.
Sometimes, business people would say they *want* the tool bar or address bar (actually they do not know what really they want in many times :-) In such case, you have to find a way to disable the Back button. If you try the JavaScript location.replace() in the second page, it will forget the past - no back any more.
As you see, it is not easy to get a *correct* solution and my suggestion may not be applicable to your case. But I am interested in any further thoughts.
Help with this problem would be greatly appreciated.
Rob
Jing Netspread Carrier http://www.netspread.com
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