Getting started

To test the breadcrumbs’ features, we need to create some content. We used here dolmen.content contents, as our breadcrumbs’ behavior works only for IBaseContent objects:

>>> import dolmen.content
>>> from grokcore.component import testing

>>> class Container(dolmen.content.Container):
...    dolmen.content.name('A dummy container')

>>> testing.grok_component('container', Container)
True

We now create our contents in an hypothetical application:

>>> from zope.component.hooks import getSite

>>> app = getSite()
>>> app['cave'] = Container()
>>> app['cave']['pot'] = Container()

To finish, we create a view. As we use a viewlet, we need a view to display something:

>>> import grokcore.view

>>> class simpleView(grokcore.view.View):
...   grokcore.view.context(dolmen.content.IBaseContent)
...   def render(self):
...     return u'For test purposes'

>>> testing.grok_component('simpleview', simpleView)
True

Adapting

The component that allows to build URLs and Breadcrumbs is a multi adapter providing the IAbsoluteUrl interface. let’s have a closer look:

>>> from zope.component import getMultiAdapter
>>> from zope.publisher.browser import TestRequest
>>> from zope.traversing.browser.interfaces import IAbsoluteURL

>>> request = TestRequest()
>>> url = getMultiAdapter((app['cave'], request), IAbsoluteURL)

>>> url
<dolmen.app.breadcrumbs.url.DescriptiveAbsoluteURL object at ...>

>>> from zope.interface.verify import verifyObject
>>> verifyObject(IAbsoluteURL, url)
True

>>> url()
'http://127.0.0.1/cave'

>>> url.breadcrumbs()
({'url': 'http://127.0.0.1', 'name': ''},
 {'url': 'http://127.0.0.1/cave', 'name': u'cave'})

Rendering

Now, we have some contents in our application. We can call our view and render the viewlet using its manager.

>>> from dolmen.app.layout import master
>>> from dolmen.app.breadcrumbs import Breadcrumbs

>>> view = getMultiAdapter((app['cave'], request), name="simpleview")
>>> view
<simpleView object at ...>

The Breadcrumbs viewlet is registered for the dolmen.app.layout.Top manager:

>>> manager = master.Top(app['cave'], request, view)
>>> viewlet = Breadcrumbs(app['cave'], request, view, manager)
>>> viewlet
<dolmen.app.breadcrumbs.crumbs.Breadcrumbs object at ...>

Our contents have no title yet. If we render the viewlet, it uses the location in the parent (__name__):

>>> viewlet.update()
>>> print viewlet.render()
<div id="breadcrumb">
  <span class="you-are-here">You are here:</span>
  <span class="crumb">
    <a href="http://127.0.0.1/cave">cave</a>
  </span>
</div>

If we set a title, it uses the title:

>>> app['cave'].title = u"My cave with a fireplace"

>>> viewlet.update()
>>> print viewlet.render()
<div id="breadcrumb">
  <span class="you-are-here">You are here:</span>
  <span class="crumb">
    <a href="http://127.0.0.1/cave">My cave with a fireplace</a>
  </span>
</div>

It works with all kind of objects although the title will only be used for objects providing dolmen.content.IBaseContent:

>>> app['cave']['pot']['bone'] = object()
>>> bone = app['cave']['pot']['bone']
>>> viewlet = Breadcrumbs(bone, request, view, manager)

>>> viewlet.update()
>>> print viewlet.render()
<div id="breadcrumb">
  <span class="you-are-here">You are here:</span>
  <span class="crumb">
    <a href="http://127.0.0.1/cave">My cave with a fireplace</a>
    <span class="breadcrumb-separator">&rarr;</span>
  </span>
  <span class="crumb">
    <a href="http://127.0.0.1/cave/pot">pot</a>
    <span class="breadcrumb-separator">&rarr;</span>
  </span>
  <span class="crumb">
    <a href="http://127.0.0.1/cave/pot/bone">bone</a>
  </span>
</div>

If the object is not locatable, we raise a TypeError:

>>> unlocatable = Container()
>>> viewlet = Breadcrumbs(unlocatable, request, view, manager)
>>> viewlet.update()
Traceback (most recent call last):
...
TypeError: There isn't enough context to get URL information. This is probably due to a bug in setting up location information.

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