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A pluggable breadcrumbs implementation based on adapters.

Project description

The z3c.breadcrumb package provides base classes for breadcrumb implementations. It allows you to write adapters for each content object which provides it’s own rules for providing the breadcrumb name, url and selection.

Detailed Documentation


The z3c.breadcrumb package provides base classes for breadcrumb implementations. It allows you to write adapters for each content object which provides it’s own rule for providing the breadcrumb name, url and selection.

Let’s do some imports we will use later.

>>> import zope.interface
>>> import zope.component
>>> from zope.publisher.interfaces.http import IHTTPRequest
>>> from zope.publisher.browser import TestRequest
>>> from zope.traversing.browser import absoluteURL
>>> from zope.container import contained
>>> from z3c.breadcrumb import interfaces
>>> from z3c.breadcrumb import browser


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)

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)
'Zope Foundation'


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)


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': ''},
 {'activeURL': True,
  'name': 'Zope Foundation',
  'url': ''}]
>>> breadcrumbs.__parent__ is office

Default breadcrumbs stops on virtual host root

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

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': ''}]


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 dependency to

  • Moved 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

  • 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

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