[Erp5-dev] Validation of multiple fields on one form

[Mikolaj Antoszkiewicz]

Łukasz Nowak wrote:
> Hello,
> 
> On 2008-04-16, 16:12:59
> Mikolaj Antoszkiewicz <mikolaj at erp5.pl> wrote:
> 
>>> Hello,
>>>
>>> On 2008-04-16, 15:41:15
>>> Mikolaj Antoszkiewicz <mikolaj at erp5.pl> wrote:
>>>
>>>> Hello,
>>>>
>>>> I've just came across such an issue:
>>>>
>>>> I'm trying to validate if a given user (actually a pair First+Last
>>>> Name) was already saved (used) in the system.
>>>>
>>>> Well, the problem is that I'd like to check both fields at the
>>>> same time, but the validating script gets only a field value from
>>>> the field it's attached to.
>>>> I've used the Request object passed also to the validating script,
>>>> to get both last and first name values, but it looks a bit ugly.
>>>>
>>>> Is there any 'nicer' way of doing such a validation?
>>> As far as I understood you are trying to validate data of object,
>>> using user interface?
>>>
>>> Wouldn't it be nicer to use proper Constraint for this type, and
>>> invoke checkConsistency while validating object?
>>  >
>> Well, sure, but I doubt You'll find a user which has to enter daily
>> and in a hurry, few Persons and then an Event or two for each of
>> them, to validate each Person with the workflow transition.
>>
>> Also, after it's been successfully validated, Person object is still 
>> editable - so much for consistency check.
>>
>> Sure, it could be read-only after validation, but then each and every 
>> small change to it's details, would mean two additional transitions
>> (at least 7 clicks - if everything is valid :) ). So in a case where
>> there is a need for a 'mass' change in a group of Persons, I can
>> picture a regular user throwing a computer through the window and
>> jumping after it after first 30 cliks...
>>
>>> Using mass workflow transition with some asynchronous messaging
>>> would give possibility to:
>>>  a mass data insertion
>>>  b then mass data validation
>>>  c mass data edition, goto b until wrong objects left
>>>
>> No mass data operations on Person type objects is to be expected here.
>>
>>> And there might be some kind of tooltip on object, which would show
>>> checkConsistency messages on object, while edited by user (eg. list
>>> presence of duplications etc).
>>>
>> At which point that tooltip would appear?
> 
> All the time. As readonly field on view.
> 
>>> That's a way, we are implementing such constraining in our
>>> implementation.
>>>
>>> Regards,
>>> Luke
>> Anyway, You haven't mentioned what is 'not nice' in my approach?
>> Field validators are there exactly for validation of data using user
>> interface.
> 
> AFAIK you are validating object data in UI. What about if you provide
> another form, or dialog in which you forget to validate that data?
> 
Well, You got a point here...

> But as generic idea: I thinking only about convention, that data shall
> be validated on data layer, not on user interface layer. Checking for
> proper values in fields (eg. proper date in DateTimeField) is something
> else.
> 
Once more, You're absolutely right. but in case of a web-based 
application it's just too rough (from the user point of view) to do it 
with data layer validation.

> I think I *feel* what is the problem, and this is related with
> limitation of UI based on HTTP without some kind of client-side helper
> (eg. AJAX). You need to provide information based on data gathered in
> system, and let user to be able to make fast (1-2 sec), on-click,
> decision. So what you suggested might be acceptable workaround, until
> user-friendly generic layer would come :)
> 
> Just thinking, as we had similar problems.
> 
> Regards,
> Luke
>