Breadcrumbs are a navigation component to help the user locate himself along a path of entities.
Breadcrumbs are displayed by default in the header section (see Layout and sections). With the default main template, the header section is composed by the logo, the application name, breadcrumbs and, at the most right, the login box. Breadcrumbs are displayed just next to the application name, thus they begin with a separator.
Here is the header section of the CubicWeb’s forge:
There are three breadcrumbs components defined in cubicweb.web.views.ibreadcrumbs:
The IBreadCrumbsAdapter adapter is defined in the cubicweb.web.views.ibreadcrumbs module. It specifies that an entity which implements this interface must have a breadcrumbs and a parent_entity method. A default implementation for each is provided. This implementation expoits the ITreeAdapter.
Note
Redefining the breadcrumbs is the hammer way to do it. Another way is to define an ITreeAdapter adapter on an entity type. If available, it will be used to compute breadcrumbs.
Here is the API of the IBreadCrumbsAdapter class:
If the breadcrumbs method return a list of entities, the cubicweb.web.views.ibreadcrumbs.BreadCrumbView is used to display the elements.
By default, for any entity, if recurs=True, breadcrumbs method returns a list of entities, else a list of a simple string.
In order to see a hierarchical breadcrumbs, entities must have a parent method which returns the parent entity. By default this method doesn’t exist on entity, given that it can not be guessed.