[Zope3-dev] Re: Z3 schemas and validation?

[Jeffrey P Shell]

On Monday, September 8, 2003, at 03:42  PM, Garrett Smith wrote:

> Anthony Baxter wrote:
>> I'm trying to use the zope3 zope.schemas package outside zope3, but 
>> I've hit a pretty basic problem - how do I actually validate
>> the object conforms to the schema? The README.txt in the schema
>> package refers to a validateMapping function that no longer exists.
>> Is it a matter of something like (assuming the objects from
>> src/zope/schema/README.txt)
>> for name in IContact.names():
>>     IContact.get(name).validate(someone.__dict__[name])
>> Shouldn't this functionality be provided in some way, that's
>> less ugly for the programmer?
>
> I.e. something like this?
>
>   from zope.schema import validateObject
>
>   object = Foo() # implements schema IFoo
>   object.bar = u'aaa'
>   object.baz = 111
>
>   try:
>     validateObject(object, IFoo)
>   except ????:
>      ...
>
> I'm not sure what sort of exception would be raised if one or more 
> fields raised a ValidationError. I would assume the caller would want 
> to have a list of errors, rather than just the first error raised. 
> (What would be more Pythonic here -- a sequence of errors, chained 
> errors, or a new exception class?)

Formulator distinguishes between 'validate' and 'validate_all'.  The 
'validate_all' methods raise a 'FormValidationError', which is a list 
of individual 'ValidationError' objects (stored in the 
FormValidationError's instance attribute 'errors').

'validate' raises ValidationError at the first failure (I believe).

I like the 'validate_all' approach personally.  But I appreciate there 
are both options.