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From "Craig R. McClanahan" <craig...@apache.org>
Subject Re: REPOST: Forcing the ActionForm to populate a field before the other
Date Thu, 02 Jan 2003 16:56:17 GMT


On Thu, 2 Jan 2003, Toni Charlot wrote:

> Date: Thu, 2 Jan 2003 10:10:32 -0500
> From: Toni Charlot <developer@fdplus.com>
> Reply-To: Struts Users Mailing List <struts-user@jakarta.apache.org>,
>      developer@fdplus.com
> To: struts-user@jakarta.apache.org
> Subject: REPOST: Forcing the ActionForm to populate a field before the
>     other
>
> I would like to have a setter method called before another.  What's the
> best way to do that in the ActionForm

There are no guarantees on the order that the setters are called.  This is
for two reasons:

* There is no rule in the HTTP or HTML specs defining the order
  in which the request parameters are sent, so it's totally up
  to the client.  And they really do operate differently.

* There is no rule in the servlet spec saying that the input order
  has to be preserved, so it's totally up to the container to decide
  how to implement this.  And they really do operate differently.

More fundamentally, though, the only reason that the setter order would
matter is if there are side effects (setting one property affects the
semantics of setting a different one).  Designing your form beans in this
way is a very poor architectural decision -- the whole point of a form
bean is to simply represent the input values that the user actually
entered on the form.  Any functionality that tries to assign "meaning" to
these inputs should be done in business logic (which can pull data out of
the form bean in any order that you need), not in the form bean itself.

>
> Thank you.

Craig McClanahan



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