zope.vocabularyregistry 1.1.1

zope.vocabularyregistry

This Zope 3 package provides a zope.schema vocabulary registry that uses utilities to look up vocabularies.

Component-based Vocabulary Registry

This package provides a vocabulary registry for zope.schema, based on the component architecture.

It replaces the zope.schema’s simple vocabulary registry when zope.vocabularyregistry package is imported, so it’s done automatically. All we need is provide vocabulary factory utilities:

>>> import zope.vocabularyregistry
>>> from zope.component import provideUtility
>>> from zope.schema.interfaces import IVocabularyFactory
>>> from zope.schema.vocabulary import SimpleTerm
>>> from zope.schema.vocabulary import SimpleVocabulary

>>> def makeVocabularyFactory(*values):
...     def vocabularyFactory(context=None):
...         terms = [SimpleTerm(v) for v in values]
...         return SimpleVocabulary(terms)
...     return vocabularyFactory

>>> zope.component.provideUtility(
...     makeVocabularyFactory(1, 2), IVocabularyFactory,
...     name='SomeVocabulary')

Now we can get the vocabulary using standard zope.schema way:

>>> from zope.schema.vocabulary import getVocabularyRegistry
>>> vr = getVocabularyRegistry()
>>> voc = vr.get(None, 'SomeVocabulary')
>>> [term.value for term in voc]
[1, 2]

If vocabulary is not found, VocabularyRegistryError is raised.

>>> try:
...     vr.get(None, 'NotAvailable')
... except LookupError as error:
...     print("%s.%s: %s" % (error.__module__, error.__class__.__name__, error))
zope.schema.vocabulary.VocabularyRegistryError: unknown vocabulary: 'NotAvailable'

We can also use vocabularies defined in local component registries. Let’s define some local sites with a vocabulary.

>>> import zope.component.hooks
>>> from zope.component import globalregistry
>>> from zope.component.globalregistry import getGlobalSiteManager

>>> from zope.interface.registry import Components
>>> class LocalSite(object):
...   def __init__(self, name):
...      self.sm = Components(
...          name=name, bases=(globalregistry.getGlobalSiteManager(), ))
...
...   def getSiteManager(self):
...       return self.sm

>>> local_site_even = LocalSite('local_site_even')
>>> local_site_even.sm.registerUtility(
...     makeVocabularyFactory(4, 6, 8), IVocabularyFactory,
...     name='SomeVocabulary', event=False)

>>> local_site_odd = LocalSite('local_site_odd')
>>> local_site_odd.sm.registerUtility(
...     makeVocabularyFactory(3, 5, 7), IVocabularyFactory,
...     name='SomeVocabulary', event=False)

Vocabularies defined in local component registries can be accessed in two ways.

1. Using the registry from within a site.

>>> with zope.component.hooks.site(local_site_even):
...     voc = getVocabularyRegistry().get(None, 'SomeVocabulary')
...     [term.value for term in voc]
[4, 6, 8]

2. Binding to a context that can be used to look up a local site manager.

>>> from zope.interface.interfaces import IComponentLookup
>>> zope.component.provideAdapter(
...    lambda number: ((local_site_even, local_site_odd)[number % 2]).sm,
...    adapts=(int, ), provides=IComponentLookup)

>>> context = 4
>>> voc = getVocabularyRegistry().get(context, 'SomeVocabulary')
>>> [term.value for term in voc]
[4, 6, 8]

Binding to a context takes precedence over active site, so we can look up vocabularies from other sites.

>>> context = 7
>>> with zope.component.hooks.site(local_site_even):
...     voc = getVocabularyRegistry().get(context, 'SomeVocabulary')
...     [term.value for term in voc]
[3, 5, 7]

If we cannot find a local site for given context, currently active site is used.

>>> from zope.interface.interfaces import ComponentLookupError
>>> def raisingGetSiteManager(context=None):
...    if context == 42:
...        raise ComponentLookupError(context)
...    return zope.component.hooks.getSiteManager(context)
>>> hook = zope.component.getSiteManager.sethook(raisingGetSiteManager)

>>> context = 42
>>> with zope.component.hooks.site(local_site_odd):
...     voc = getVocabularyRegistry().get(context, 'SomeVocabulary')
...     [term.value for term in voc]
[3, 5, 7]

CHANGES