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

[Garrett Smith]

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?)

Alternatively (though personally I don't like it):

   errors = []
   validateObject(object, IFoo, errors)


  -- Garrett