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From Andrew Hill <andrew.david.h...@gridnode.com>
Subject Re: Wouldn't validation be better performed by Actions rather than ActionForms?
Date Mon, 21 Mar 2005 03:51:08 GMT
Yes.

I always validate in Actions and not in the form itself (though I often 
delegate to a seperate helper class from the action (and configure the 
helper in a subclass of ActionMapping and have an abstract action 
superclass manage its lifecycle)).

Validating in the form I find to be troublesome. I still prefer to have 
good old fashioned hand coded forms (nice and solid to compile against!) 
but the point where validate() is called is simply never the point at 
which I wish to validate, and my actions would usually need to do some 
work to prepare for the view so I dont want struts going off and 
forwarding back to the input for me. Yes I could set things up using 
seperate setup actions as my 'input' url, but its just a nuisance. (My 
actions do have a tendency towards being page controllers...)

Havent got around to learning to use the validator stuff. My validation 
  (after the trivial data type checking stuff) usually needs to to 
require actual code as it can be quite convulted depending on the 
requirements.

As for dispatch actions... hehe Im not making *that* mistake again. 
urrrgh! Ill stick with a normal action and an 'if' statement in future 
thanks :-)



Lawrie Gallardo wrote:
> I'm still relatively new to Struts, but I can't help but feel that 
> validation would be better performed by Action classes rather than 
> ActionForm classes.
> 
> It seems to me that, ideally, you want
> 1. Validation,
> 2. Transformations (ie convert separate day, month and year HTML fields 
> to Java Date object), and
> 3. Mapping of ActionForm fields (/HTML parameters) to Domain POJOs / DTOs
> to all be configured in the same config file (to minimise duplication) 
> and to be implemented in the same class rather than scattered between 
> multiple config files and classes.
> 
> Now, if my understanding is correct:
> 1. There is always a one-to-one mapping between an ActionForm and an 
> ActionMapping,
> 2. Struts best practice is to have each Action class handle all possible 
> operations for the HTML request it deals with using DispatchLookupAction 
> or something similar,
> 3. Almost noone creates ActionForms manually any more - they use 
> DynaActionForm (or validating variations of this). And for those who do 
> still create ActionForms manually, they don't offer anything in the way 
> of reuse, and are basically throw-away classes.
> 
> Now if this is the case, would it not be better to have the ActionForm 
> as basically a dum data holder and have the validation method in the 
> Action classes instead? The strus-config.xml file could contain all the 
> required declarative validation, transformation and mapping info, and 
> the Action class could contain any validation, transformation, and 
> mapping operations that were too complicated to be set up declaratively.
> 
> Is it just down to design decisions made in early versions of Struts and 
> backward compatibility that things are the way they are? Or are there 
> good arguments for having the validation method in ActionForm? Am I 
> missing something here?
> 
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