z3c.breadcrumb 4.0

IBreadcrumb

Let’s define a interface and a content object.

>>> class IOffice(zope.interface.Interface):
...     """Office interface."""

>>> @zope.interface.implementer(IOffice)
... class Office(contained.Contained):
...     def __init__(self, label):
...         self.label = label
...         self.activeURL = True

>>> office = Office('Zope Foundation')
>>> office.__name__ = 'ZF'

There is a generic breadcrumb implementation which is registered by default. If we do not implement a custom IBreadcrumb the generic adapter will return the title or __name__ of the item. Let’s register the default adapter, this is normally done in configure.zcml:

>>> zope.component.provideAdapter(browser.GenericBreadcrumb)

And see what we get:

>>> request = TestRequest()
>>> breadcrumb = zope.component.getMultiAdapter((office, request),
...     interfaces.IBreadcrumb)
>>> breadcrumb.name
'ZF'

We can also implement a custom IBreadcrumb adapter and provide another name for the breadcrumb name:

>>> @zope.interface.implementer(interfaces.IBreadcrumb)
... @zope.component.adapter(IOffice, IHTTPRequest)
... class BreadcrumbForOffice(object):
...
...     def __init__(self, context, request):
...         self.context = context
...         self.request = request
...
...     @property
...     def name(self):
...         return self.context.label
...
...     @property
...     def url(self):
...         return absoluteURL(self.context, self.request)
...
...     @property
...     def activeURL(self):
...         return self.context.activeURL

Let’s register the custom IBreadcrumb adapter for IOffice:

>>> zope.component.provideAdapter(BreadcrumbForOffice)

And check the new breadcrumb name:

>>> breadcrumb = zope.component.getMultiAdapter((office, request),
...     interfaces.IBreadcrumb)
>>> breadcrumb.name
'Zope Foundation'

CustomNameBreadcrumb

Let’s define another interface and a content object.

>>> class IOfficeContainer(zope.interface.Interface):
...     """Container of offices."""

>>> @zope.interface.implementer(IOfficeContainer)
... class OfficeContainer(contained.Contained):
...     pass

>>> offices = OfficeContainer()
>>> offices.__name__ = 'offices'

If the custom name for this kind of object is always the same it would quickly get tedious to write a full IBreadcrumb implementation. As a shortcut you can use CustomNameBreadcrumb to get an adapter that acts like GenericBreadcrumb, but returns the name you want.

>>> adapter = browser.CustomNameBreadcrumb('Offices')
>>> adapter
<class 'z3c.breadcrumb.browser.CustomNameBreadcrumb('Offices')'>
>>> zope.component.provideAdapter(adapter,
...     adapts=(IOfficeContainer, IHTTPRequest))

>>> breadcrumb = zope.component.getMultiAdapter((offices, request),
...     interfaces.IBreadcrumb)
>>> breadcrumb.name
'Offices'

IBreadcrumbs

There is also a IBreadcrumbs adapter which knows how to collect breadcrumb informations for each item he traverses. We need to setup a little bit of infrastructure:

>>> root = rootFolder
>>> root['office'] = office

Register the IBreadcrumbs adapter:

>>> zope.component.provideAdapter(browser.Breadcrumbs,
...     (zope.interface.Interface, zope.interface.Interface),
...     interfaces.IBreadcrumbs)

Now we can collect breadcrumbs for our items. You can see the url is correct and the label Zope Foundation is collected by the custom IBreadcrumb adapter:

>>> breadcrumbs = zope.component.getMultiAdapter((office, request),
...     interfaces.IBreadcrumbs)
>>> from pprint import pprint
>>> pprint(list(breadcrumbs.crumbs))
[{'activeURL': True,
  'name': 'top',
  'url': 'http://127.0.0.1'},
 {'activeURL': True,
  'name': 'Zope Foundation',
  'url': 'http://127.0.0.1/office'}]

>>> breadcrumbs.__parent__ is office
True

Default breadcrumbs stops on virtual host root

>>> request._vh_root = office
>>> pprint(list(breadcrumbs.crumbs))
[{'activeURL': True,
  'name': 'Zope Foundation',
  'url': 'http://127.0.0.1'}]

If the breadcrumb of an item is a Null-adapter, then the item is ignored.

>>> from zope.traversing.interfaces import IContainmentRoot
>>> zope.component.provideAdapter(
...     lambda c, r: None,
...     (IContainmentRoot, IHTTPRequest),
...     interfaces.IBreadcrumb)

>>> request = TestRequest()
>>> breadcrumbs = zope.component.getMultiAdapter(
...     (office, request), interfaces.IBreadcrumbs)
>>> pprint(list(breadcrumbs.crumbs))
[{'activeURL': True,
  'name': 'Zope Foundation',
  'url': 'http://127.0.0.1/office'}]

4.0 (2025-04-14)

• Replace pkg_resources namespace with PEP 420 native namespace.

3.1 (2025-02-14)

• Add support for Python 3.12, 3.13.

• Drop support for Python 3.7, 3.8.

3.0 (2023-02-24)

• Drop support for Python 2.6, 2.7, 3.3, 3.4.

• Add support for Python 3.7, 3.8, 3.9, 3.10, 3.11.

2.0.0 (2015-11-09)

• Standardize namespace __init__

2.0.0a1 (2013-02-27)

• Added support for Python 3.3.

• Moved zope.app.testing dependency to zope.site.testing.

• Moved zope.app.container dependency to zope.container.

• Replaced deprecated zope.interface.implements usage with equivalent zope.interface.implementer decorator.

• Dropped support for Python 2.4 and 2.5.

1.1.1 (2010-12-12)

• Added needed but not declated test dependency on zope.app.container.

• Using Python’s doctest module instead of depreacted zope.testing.doctest.

1.1.0 (2009-05-29)

• Feature: Added ability to register a Null-adapter as a breadcrumb. A null-breadcrumb will cause the item not to be displayed in the breadcrumbs.

1.0.3 (2008-12-13)

• Bug: Fixed IBreadcrumbs to match implementation.

• Clean up dependencies.

1.0.2 (2008-01-23)

• Bug: Fixed the package’s long description.

• Feature: Use the correct DocFileSuite class that counts tests properly.

1.0.1 (2007-01-21)

• Bug: Test coverage brought up to 100%.

• Feature: Register default IBreadcrumbs adapter.

• Bug: Default IBreadcrumbs stops only on virtual host root, not on ISite object

1.0.0 (7/10/2007)

• Initial Release