validation in the form vs. validation in the business domain object

[James Hoffa <jm...@yahoo.com>]

What ideas do people have about where is the best
place to perform validation of items that come back
from ActionForms?

Example: check to see if the user's choice of
motherboard, memory, and cpu are compatible with each
other.

Following the struts example, it seems like the
validate() method in an ActionForm is used only for
light validation (i.e. checking to see if something
was left blank, or checking for alpha and numeric
chars). This approach seems correct to me, since there
should not be business logic inside the ActionForm. 

That leaves most of the work to the business domain
object since any nontrivial application will not have
business logic in the Action class either.

The business domain object, in many cases, will be
accessed remotely from the Action class.

Does it make sense for the business domain object to
return an ActionErrors object(it is serializable)?  I
am not 100% comfortable yet with the idea of importing
ActionErrors into the business object since it couples
it to struts to a certain extent, and it could
potentially be large.

Is the only alternative to send back a list of generic
error codes from the business object that each map to
an ActionError and the Action class could add the
ActionErrors? (i think i'd  rather import actionerrors
in this case) 

What are some of the "best practices" people have
found to work for this problem?

Craig and ALL Struts creators:  Struts is really
great. Thank you for all of your hard work. It is
definitely something to be proud of.

__________________________________________________
Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail
http://personal.mail.yahoo.com/

Re: validation in the form vs. validation in the business domain object

[David Winterfeldt <dw...@yahoo.com>]

I think it is reasonable to have a feature request to
have ActionError have a constructor that takes an
Object array since especially since MessageResources
can do this.  So you could either send a proposal to
the e-mail list or the better place would probably be
to submit the request through bugzilla so it doesn't
get lost.  

As far as having more than four args, I think this was
a decision based on how many args to support in the
tags, but I'm not sure.  The MessageResources
getMessage(Locale locale, String key, Object args[])
directly passes in the object array to an instance of
java.text.MessageFormat.  So if ActionError could take
an Object[] then it could call the method in
MessageResources that takes an array and it doesn't
look like MessageFormat has any limitations for the
number of arguments it can handle.

David

--- William Jaynes <wj...@mediaone.net> wrote:
> David,
> 
> Barracuda does this nested Exception procedure (as I
> believe you
> probably know already). I've been playing with their
> forms package a bit
> in a Struts app of mine. I like the scheme, in
> general, but the problem
> I have with their particular implementation is as
> follows... The
> Validator classes that throw the
> ValidationExceptions set the exception
> message to be a resource key. At some point in the
> Action class I check
> for validation exceptions and iterate through any
> that exist. I use
> getMessage() to get the key and add a new
> ActionError to the
> ActionErrors object. The problem comes with messages
> that need
> substitutions. If I have a resource message like
> "Date should be between
> {0} and {1}" I need some scheme for the Validator
> class to communicate
> the specific parameters that go along with the
> resource key. Seems to me
> that the ValidationException class needs a property
> like
> MessageArguments (possibly an array of Objects,
> since that is ultimately
> what MessageResources needs) that the Validator
> class can set and the
> Action class can get as it iterates through the
> exceptions.
> 
> I've coded extensions to the Barracuda classes for
> this, but it's
> awkward and means I need to always use my own
> versions of Validator
> classes.
> 
> On the Struts side of things, I find that if I have
> a resource key and
> an array of Objects that are the substitutions to be
> used in the
> message, there's no ActionError constructor that
> will let me pass in the
> array. Instead I have to manipulate things and use
> one of the existing
> constructors that specify each replacement value
> explicitly. Of course I
> could extend and make my own, but it seems
> reasonable that ActionError
> should have such a constructor. It would also permit
> more than 4
> substitutions, if anyone would need more.
> 
> Just my thoughts,
> Will
> 
> 
> ----- Original Message -----
> From: "David Winterfeldt" <dw...@yahoo.com>
> To: <st...@jakarta.apache.org>
> Sent: Wednesday, June 20, 2001 3:05 AM
> Subject: Re: validation in the form vs. validation
> in the business
> domain object
> 
> 
> > Someone I know extended Exception and they throw
> > nested exceptions that eventually are passed back
> to
> > the Struts layer and then an ActionError is
> > constructed for each exception.  Something like
> that
> > seems like a clean way to keep things separated. 
> I
> > did something similiar on a project with a Swing
> and
> > EJBs.
> >
> > David
> >
> > --- James Hoffa <jm...@yahoo.com> wrote:
> > > What ideas do people have about where is the
> best
> > > place to perform validation of items that come
> back
> > > from ActionForms?
> > >
> > > Example: check to see if the user's choice of
> > > motherboard, memory, and cpu are compatible with
> > > each
> > > other.
> > >
> > > Following the struts example, it seems like the
> > > validate() method in an ActionForm is used only
> for
> > > light validation (i.e. checking to see if
> something
> > > was left blank, or checking for alpha and
> numeric
> > > chars). This approach seems correct to me, since
> > > there
> > > should not be business logic inside the
> ActionForm.
> > >
> > > That leaves most of the work to the business
> domain
> > > object since any nontrivial application will not
> > > have
> > > business logic in the Action class either.
> > >
> > > The business domain object, in many cases, will
> be
> > > accessed remotely from the Action class.
> > >
> > > Does it make sense for the business domain
> object to
> > > return an ActionErrors object(it is
> serializable)?
> > > I
> > > am not 100% comfortable yet with the idea of
> > > importing
> > > ActionErrors into the business object since it
> > > couples
> > > it to struts to a certain extent, and it could
> > > potentially be large.
> > >
> > > Is the only alternative to send back a list of
> > > generic
> > > error codes from the business object that each
> map
> > > to
> > > an ActionError and the Action class could add
> the
> > > ActionErrors? (i think i'd  rather import
> > > actionerrors
> > > in this case)
> > >
> > > What are some of the "best practices" people
> have
> > > found to work for this problem?
> > >
> > > Craig and ALL Struts creators:  Struts is really
> > > great. Thank you for all of your hard work. It
> is
> > > definitely something to be proud of.
> > >
> > >
> __________________________________________________
> > > Do You Yahoo!?
> > > Get personalized email addresses from Yahoo!
> Mail
> > > http://personal.mail.yahoo.com/
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Get personalized email addresses from Yahoo! Mail
> > http://personal.mail.yahoo.com/
> 


__________________________________________________
Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail
http://personal.mail.yahoo.com/

Re: validation in the form vs. validation in the business domain object

[William Jaynes <wj...@mediaone.net>]

David,

Barracuda does this nested Exception procedure (as I believe you
probably know already). I've been playing with their forms package a bit
in a Struts app of mine. I like the scheme, in general, but the problem
I have with their particular implementation is as follows... The
Validator classes that throw the ValidationExceptions set the exception
message to be a resource key. At some point in the Action class I check
for validation exceptions and iterate through any that exist. I use
getMessage() to get the key and add a new ActionError to the
ActionErrors object. The problem comes with messages that need
substitutions. If I have a resource message like "Date should be between
{0} and {1}" I need some scheme for the Validator class to communicate
the specific parameters that go along with the resource key. Seems to me
that the ValidationException class needs a property like
MessageArguments (possibly an array of Objects, since that is ultimately
what MessageResources needs) that the Validator class can set and the
Action class can get as it iterates through the exceptions.

I've coded extensions to the Barracuda classes for this, but it's
awkward and means I need to always use my own versions of Validator
classes.

On the Struts side of things, I find that if I have a resource key and
an array of Objects that are the substitutions to be used in the
message, there's no ActionError constructor that will let me pass in the
array. Instead I have to manipulate things and use one of the existing
constructors that specify each replacement value explicitly. Of course I
could extend and make my own, but it seems reasonable that ActionError
should have such a constructor. It would also permit more than 4
substitutions, if anyone would need more.

Just my thoughts,
Will


----- Original Message -----
From: "David Winterfeldt" <dw...@yahoo.com>
To: <st...@jakarta.apache.org>
Sent: Wednesday, June 20, 2001 3:05 AM
Subject: Re: validation in the form vs. validation in the business
domain object


> Someone I know extended Exception and they throw
> nested exceptions that eventually are passed back to
> the Struts layer and then an ActionError is
> constructed for each exception.  Something like that
> seems like a clean way to keep things separated.  I
> did something similiar on a project with a Swing and
> EJBs.
>
> David
>
> --- James Hoffa <jm...@yahoo.com> wrote:
> > What ideas do people have about where is the best
> > place to perform validation of items that come back
> > from ActionForms?
> >
> > Example: check to see if the user's choice of
> > motherboard, memory, and cpu are compatible with
> > each
> > other.
> >
> > Following the struts example, it seems like the
> > validate() method in an ActionForm is used only for
> > light validation (i.e. checking to see if something
> > was left blank, or checking for alpha and numeric
> > chars). This approach seems correct to me, since
> > there
> > should not be business logic inside the ActionForm.
> >
> > That leaves most of the work to the business domain
> > object since any nontrivial application will not
> > have
> > business logic in the Action class either.
> >
> > The business domain object, in many cases, will be
> > accessed remotely from the Action class.
> >
> > Does it make sense for the business domain object to
> > return an ActionErrors object(it is serializable)?
> > I
> > am not 100% comfortable yet with the idea of
> > importing
> > ActionErrors into the business object since it
> > couples
> > it to struts to a certain extent, and it could
> > potentially be large.
> >
> > Is the only alternative to send back a list of
> > generic
> > error codes from the business object that each map
> > to
> > an ActionError and the Action class could add the
> > ActionErrors? (i think i'd  rather import
> > actionerrors
> > in this case)
> >
> > What are some of the "best practices" people have
> > found to work for this problem?
> >
> > Craig and ALL Struts creators:  Struts is really
> > great. Thank you for all of your hard work. It is
> > definitely something to be proud of.
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Get personalized email addresses from Yahoo! Mail
> > http://personal.mail.yahoo.com/
>
>
> __________________________________________________
> Do You Yahoo!?
> Get personalized email addresses from Yahoo! Mail
> http://personal.mail.yahoo.com/

Re: validation in the form vs. validation in the business domain object

[David Winterfeldt <dw...@yahoo.com>]

Someone I know extended Exception and they throw
nested exceptions that eventually are passed back to
the Struts layer and then an ActionError is
constructed for each exception.  Something like that
seems like a clean way to keep things separated.  I
did something similiar on a project with a Swing and
EJBs.

David

--- James Hoffa <jm...@yahoo.com> wrote:
> What ideas do people have about where is the best
> place to perform validation of items that come back
> from ActionForms?
> 
> Example: check to see if the user's choice of
> motherboard, memory, and cpu are compatible with
> each
> other.
> 
> Following the struts example, it seems like the
> validate() method in an ActionForm is used only for
> light validation (i.e. checking to see if something
> was left blank, or checking for alpha and numeric
> chars). This approach seems correct to me, since
> there
> should not be business logic inside the ActionForm. 
> 
> That leaves most of the work to the business domain
> object since any nontrivial application will not
> have
> business logic in the Action class either.
> 
> The business domain object, in many cases, will be
> accessed remotely from the Action class.
> 
> Does it make sense for the business domain object to
> return an ActionErrors object(it is serializable)? 
> I
> am not 100% comfortable yet with the idea of
> importing
> ActionErrors into the business object since it
> couples
> it to struts to a certain extent, and it could
> potentially be large.
> 
> Is the only alternative to send back a list of
> generic
> error codes from the business object that each map
> to
> an ActionError and the Action class could add the
> ActionErrors? (i think i'd  rather import
> actionerrors
> in this case) 
> 
> What are some of the "best practices" people have
> found to work for this problem?
> 
> Craig and ALL Struts creators:  Struts is really
> great. Thank you for all of your hard work. It is
> definitely something to be proud of.
> 
> __________________________________________________
> Do You Yahoo!?
> Get personalized email addresses from Yahoo! Mail
> http://personal.mail.yahoo.com/


__________________________________________________
Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail
http://personal.mail.yahoo.com/