[Zope3-Users] Re: zope.schema Question

[Tim Cook]

On Mon, 2008-07-07 at 00:46 +0200, Philipp von Weitershausen wrote:

> 
>    description=Object(
>        schema=IFoo,
>        ...
>        )
> 
> So the zope.schema.Object field is really about specifying objects that 
> provide a certain schema. It's not for *arbitrary* objects (use 
> zope.schema.Field or zope.interface.Attribute here).

Thanks Philipp.

Field doesn't work because it expects a unicode type.

Attribute works but I would like to be able to flag it as 'required'
which is not part of the Attribute class.

Object would work if it would allow types that subclass from the schema
given.

A concrete example:

IItemStructure(Interface)
   IItemTree(IItemStructure)
   IItemTable(IItemStructure)
   ...

ItemTree(ItemStructure)
  implements(IItemTree)

ItemTable(ItemStructure)
  implements(IItemTable)

...

Now I want to allow description to be any descendant of ItemStructure.
So I had hoped that:

    description=Object(
        schema=IItemStructure,
        title=_(u"Description"),
        description=_(u"Description of the activity."),
        required=True,
    )
  
would provide that functionality.  It still throws a WrongTypeError.

I feel like the answer lies somewhere in the zope.interface.implement*
functions but I lack the Zen to get the right combination.

Thanks,
Tim
             






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Timothy Cook, MSc
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