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From Sylvain Wallez <>
Subject Re: [RT] Revisiting Woody's form definition
Date Wed, 30 Jul 2003 14:00:16 GMT
Marc Portier wrote:

> Sylvain Wallez wrote:


>> Validators currently exist only for datatypes, and not yet for 
>> bindings (this is on my todo list).
> yep, some nuance though:
> there should be only one validation cycle!
> what I mean is:
> - we probably do want to be able to express validation-rules by using 
> some of the syntax we currently find in the binding file, that is 
> based on the business-object models we want to manipulate
> - however: I don't see a reason for specific validation that only 
> kicks in when doing the save-binding (i.e. typically at the end of the 
> use case) since that would defy the whole idea of having a 
> woody-form-model that can validate *early* some user-input?

When the form is bound to application data, datatype validation isn't 
enough and there *must* be some application data-related validation 
before saving.

Let's take the simple use case of user registration :
- datatype-level validation : name is not longer than 20 characters (--> 
"please use a shorter name")
- application data-level validation : name doesn't already exist in the 
database (--> "this name is already used. Please choose another one").

Note that the second validation, although binding-specific, can be 
performed early and doesn't need to be delayed until the save-binding.

> having said that I still think the validators are tied to datatypes, 
> only some of those datatypes are to be retrieved or introspected from 
> the business domain directly (and can be expressed as such, including 
> business specific validation) 

I the above example, the second validation cannot be defined on the 
datatype, since it must be checked only when a *new* user is created and 
not everywhere a user name is input. It's therefore specific to the 
registration form.

> or am I missing something?
> (maybe all of this is introduced by 'binding' being a bad name for 
> what it currently is: it really just is run-time data-mapping, not 
> design-time typing) 

Uh ? What do you mean by "design-time" and "run-time" ?


Sylvain Wallez                                  Anyware Technologies 
{ XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }
Orixo, the opensource XML business alliance  -

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