Re: a question about MVC concept

["David Morris" <David.Morris@xxxxxxxxxxxxx>]

Patrick,

What has worked for me in several environments is to have edits that
are
related to the database (model) and view. An edit is basically a
message
and a field. A field has a value, a name, and container. The view can
perform edits if any are associated with values being displayed. The
model
is edited in all cases on direct updates or the edit process can be
triggered
by a trigger (if the caller went through another interface). I have
used RPG
and with other databases, stored procedures. In either case, the
trigger only
performs validations if it came through an unsupported interface.

I wrote a framework to do this in RPG that we still use. I also worked
some
on a Java based framework that is now part of the Jakarta Commons
Validator
framework. It is based on the same principles and would be a good place

to start looking. I have used that framework with Struts where the
expectation
is that it will only be used to support the View, which is OK but you
should also
use this to support the Model.

David Morris

>>> P.Goovaerts@Clipper.Be 09/17/02 01:23AM >>>
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As the Controller is responsible to delegate requests and responses,
the
View responsible to display results and request-forms and the Model
responsible to handle data, where do we put testing of inputfields,
processing of resultvalues etc?
example:
FormA : request parameter
FormB : response data (db-record details)
FormC : confirmation form for datachanges

1) User enters parameter in FormA and submits.
2) Controller forwards parameter to Model
3) Model retrieves data from db
4) Model signals Controller succesfull retrieval
5) Controller forwards FormB to browser
6) FormB is displayed in browser
7) User changes data in FormB and submits
...
8) ??? tests data and processes specific vars (varC = varA * varB)
...
9) FormC is displayed in browser

one can do this in the Controller or Model.  I think the Model should
do
this because
(A) it must stay independent of Controller
(B) Model can be used by ClientServer java application too



"   I don't have problems, only challenges...  "

Patrick Goovaerts