Hi,

On Sat, Apr 15, 2006 at 08:41:57AM -0700, Ruben Gutierrez wrote:
> I'm having trouble understanding some of the semantics or conventions with
> Zope. One simple question I have is how do I create a list of selectable
> values in a form. I understand you can use a Choice object, but I would like
> to populate the list with all available objects of a specific type, within a
> specific container. For example, I have a form which requests an address.
> How do I populate the State (e.g., CA, HI, NY) field from a list of stored
> State objects? I don't want to include all states, as some may not be
> relevant (maybe the form is region-specific). But, I also don't want to
> statically list the states in a Choice declaration, either.

Sounds like a classic use case for a vocabulary.

Not tested:

*configure.zcml*
[...]
   <utility
      name="States"
      factory="vocabularies.StatesFactory"
      provides="zope.app.schema.interfaces.IVocabularyFactory"
      />
[...]

*vocabularies.py*
from zope.interface import implements
from zope.schema.vocabulary import SimpleVocabulary, SimpleTerm 
from zope.app.schema.interfaces import IVocabularyFactory

class StatesFactory():
   implements(IVocabularyFactory)

   def __call__(self,context):
      terms=[SimpleTerm(name,title=name) for name in context.keys()]
      voc=SimpleVocabulary(terms)
      return voc


The vocabulary factory makes use of the provided context object (which is
the current content object when editing a form. Just use the vocabulary in a
choice field:

*interfaces.py*
[...]
class IMyObject(Interface):
   choice=Choice(
      title=u'States',
      vocabulary='States'
      required=True
   )
[...]


Regards,

Frank
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