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From Michael McGrady <m...@michaelmcgrady.com>
Subject Re: Why doesn't ActionForm's constructor have access to HttpServletRequest?
Date Tue, 03 Feb 2004 07:17:41 GMT
I think you really want something other than an ActionForm if you want to 
do this.  Why anyone would use an ActionForm to do this makes no sense to 
me.  If you want the request object, then it is in the Action.  That is 
where it should be.

At 06:59 PM 2/2/2004, Martin Cooper wrote:
>I can't read Craig's mind ;-) , but I would say that the main reason an
>ActionForm's constructor doesn't get passed the request (or anything else)
>is because it is (intended to be) a form *bean*. One of the primary
>characteristics of a JavaBean is that is that it must have a no-args
>constructor. That allows it to be instantiated from anywhere. Passing a
>request instance to the constructor presupposes that an ActionForm is
>constructed only in the context of a request.
>
>A secondary reason, in my mind, is that passing a request to the constructor
>would encourage people to stash it away as member data, which would not be
>too cool if the bean was created in session scope...
>
>--
>Martin Cooper
>
>
>"Jeff Skubick" <jeff.skubick@mci.com> wrote in message
>news:003a01c3e9dd$43229550$92a238a6@mcilink.com...
>Is the absence of a reference to the HttpServletRequest object that
>triggered the creation of a new ActionForm object in its constructor a
>historical artifact or oversight, or was it an intentional decision whose
>motivation and rationale remains 100% valid and relevant today?
>
>At the moment, I'm in a quandry. I see no way to usefully use nested form
>beans to encapsulate administrable users in my web app without somehow
>getting a hold of a list of objects representing those administrable users
>from the session context of the user who's administering them (the list's
>composition depends partially upon the user doing the administration) so I
>can prepopulate the list for its initial display.
>
>On the other hand, I'm worried that ActionForm's original creator was
>absolutely determined to keep ActionForm's constructor from ever knowing
>anything about the user or request that triggered its creation in the first
>place for some reason, like Struts casually re-using old ActionForm
>instances to satisfy new requests. On the other hand, I know it might just
>be a historical artifact that seemed like a good idea at the time, but
>doesn't really have any major implications either way.
>
>So... if I implement my own RequestProcessor class that overrides the
>default processActionForm method to call my own ActionForm-extending bean's
>constructor an explicitly pass it a reference to the HttpServletRequest
>object so it can fetch the HttpSession object and find the object that tells
>it everything else it needs to know to pre-populate the form bean prior to
>display, am I violating any sacred assumption made by other parts of Struts?
>Or am I OK?
>
>
>
>
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