RE: how to persist id parameter?

[Gurps <g...@gurpal.co.uk>]

Patrick Casey wrote:
> 
> 
> 	I'd warn against using persistent ID objects as keys for edit forms.
> The problem is that Tapestry persists properties on a page/session key. So
> for any given session, page "foo" has a set of persistent properties.
> 
> 	Lets say though that you have a page called "editUser".
> 
> 	You have a list of users.
> 	User clicks open in new tab on bob. 
> 	editUser -> Bob opens up. Key = Bob
> 	User clicks open in new tab on ted.
> 	editUser -> ted opesns up. Key = Ted.
> 	User update's bob's entry. 
> 	User presses save.
> 	Ted's record just got updated.
> 
> 	The solution turns out to be stuffing the edited in the form via a
> hidden field. Stuff it on "top" of the form so it bootstraps the record
> during rewind just like you're doing, but don't trust the page to persist
> it
> for you; send it out with the form so you can guarantee it comes back with
> the form.
> 
> 	--- Pat
> 
>> -----Original Message-----
>> From: Steven Wisener [mailto:swisener@gmail.com]
>> Sent: Tuesday, July 19, 2005 7:26 PM
>> To: Tapestry users; Jer Kah
>> Subject: Re: how to persist id parameter?
>> 
>> I think he got that far...the problem is posting back to the form. I
>> made the ID property persistent to solve the problem (it is stored in
>> the session, so it won't be null on the second page render), but you
>> should be able to use a Hidden component as well:
>> 
>> In your form, add:
>> 
>> <span jwcid="@Hidden" value="ognl:id"
>> listener="ognl:listeners.initObject"
>> />
>> 
>> If the rest of the components rely on the object being initialized,
>> make sure it appears first in the form. Your page class should look
>> something like this:
>> 
>> public void pageBeginRender(PageEvent event) {
>>     if (getId() != null) {
>>         initObject(event.getRequestCycle());
>>     }
>> }
>> 
>> public void initObject(IRequestCycle cycle) {
>>     setObject(getObjectFromDatabase(getId());
>> }
>> 
>> So here's the basic flow: The first time the page is loaded, the id
>> property is set and initObject loads it. When the form is submitted,
>> the id is not set yet in pageBeginRender, so initObject is not called.
>> When the render hits the Hidden component however, initObject is
>> called because it is its listener method. As long as you only need the
>> object loaded after the Hidden component is rendered in the rewind,
>> you should be golden. I haven't actually tested this out yet, but I
>> think it should work.
>> 
>> --Steven
>> 
>> 
> 
> 
> 

how exactly would you "stuff" the parameter?
Thanks
-- 
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