Hi Inge.

I use the FlowSynchronizer pattern that Sohail linked to,
and here's how I avoid code duplication.

In my T3 apps the FlowSyncronizer is stored in the Visit object.
My border component includes the token in every page:
<input jwcid="@Hidden" value="ognl:page.visit.flowSynchronizer.token"/>

In addition, I didn't like the exceptions, so instead:
    private boolean resubmit;
    public void setToken(String token)
    {
        // first compare the token
        if (this.token == null || !this.token.equals(token))
        {
            resubmit = true;
        }
        else
        {
            // reset token on match -> subsequent duplicate submission will fail
            this.token = null;
            resubmit = false;
        }
    }

My BasePage class has:
    public boolean isResubmit()
    {
        // check if this cycle is a resubmit (before doing inserts etc)
        Visit visit = (Visit)getVisit();
        return visit.flowSynchronizer.isResubmit();
    }

Then in any page where you need to know, just call isResubmit().

Cheers,
Nick.


Inge Solvoll wrote:
This is one of the cases where it would be really really sweet to be able to
extend components, including specifications...

On 3/2/06, Geoff Longman <[EMAIL PROTECTED]> wrote:

You could craft your own Form component that handles the hidden and
use the tapestry-flash thingy to save the token

Geoff

On 3/2/06, Inge Solvoll <[EMAIL PROTECTED]> wrote:

I've tried to copy the token-approach from struts into Tapestry, to

avoid

crashes when the user hits the "refresh"-button in the browser. Using

this

approach, the html rendered can only be submitted once. My problem is

that

the code I've written so far requires too much code copying and

repeating,

and I was wondering if someone has ideas on how to make the

implementation a

bit less intrusive for my pages.

I could include this code in my base class that all my page classes

inherit

from, but then I would have to inject WebRequest into every single page

in

my application, and that's not the tapestry way to do page design, is

it?

I'm pretty sure that this is functionality that I need in all my pages
(refresh of a post causes crash most of the times in my tapestry code).
Maybe this can be done with a servlet filter, or better, with a HiveMind
service that intercepts the request?

Here's my code so far:

public void pageBeginRender(PageEvent event) {
   if (getRequestCycle().isRewinding()) {
     String token = getRequest().getParameter("token");
     if (token == null || !token.equals(getToken())) {
       log.error("Token for page is not valid, redirect to obtain last

good

state");
       throw new PageRedirectException(this);
     }
   }
   else {
     setToken(generateToken());
   }

}

.html:
<input jwcid="@Any" type="hidden" name="token" value="ognl:token"/>

.page:
<property name="token" persist="session"/>


An article on the subject:
http://www.javalobby.org/java/forums/m91956568.html




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