[Zope-dev] Stumped about handling this particular exception...

[Tres Seaver]

Jim Fulton wrote:
> Amos Latteier wrote:
> >
> 
> (snip)
> 
> > It may be that ZPublisher doesn't have much business validating form input.
> 
> I agree. ;)
> 
> > When I complain to Jim Fulton that the converters are pretty lame he
> > usually tells me that they are not for form validation, but for argument
> > marshalling.
> 
> Exactly.  Input validation, error reporting, and other UI activities
> should be done at a much higher level.  ZPublisher is a very low-level
> tool meant for basic communication.

Actually, the ideal would be to have as much of the shallow, "pure UI" type
validation happen on the client side:  required fields, valid integers / dates /
phone numbers, etc.  Only "deep" validations (those which depend on actual
business logic) should be done in Zope.  I recall a chunk of DTML from this list
which I used at one point (but can't find now :) to generate simple JavaScript
validations, based on the converter types.  Worked nicely, if in a fairly
limited scope.

> 
> Obviously, we made the mistake early on of introducting "required",
> which really is an input validation feature.  This was before we realized
> that we couldn't hope to do a good job of validation at such a low level.
> 
> 
> > Improving the ZPublisher converters is a worthwhile problem, IMO.
> 
> I agree,  It would be nice to do more sophisticated marshalling. ;)
> 
> > In
> > addition, making ZPublisher's error reporting more flexible is also a
> > worthwhile project.
> 
> Well, It would be worthwhile to make ZPublisher provide better hooks
> to let application handle errors detected by ZPublisher.  This is
> definately on the to do list.
> 
> I also think that a default value mechanism of some kind would
> make sense.  This would help in other situations too.

I personally would like to see the default behavior for exception handling be to
render the exception object as visible HTML.  While a Python backtrace might be
disconcerting to some users, the "sorry, this site is experiencing technical
difficulties" is hardly less so.


-- 
=========================================================
Tres Seaver         tseaver@palladion.com    713-523-6582
Palladion Software  http://www.palladion.com