autobreadcrumbs 2.0.0
Django application to add breadcrumbs to your pages
License: MIT

.. _breadcrumb: http://en.wikipedia.org/wiki/Breadcrumb_%28navigation%29#Websites
.. _Django internationalization system: https://docs.djangoproject.com/en/dev/topics/i18n/

Introduction
============

**AutoBreadcrumbs** is a Django application to automatically build a breadcrumb in your website like
this : ::

  Home > Some page > Some child page

Each *crumb* displays a title with a link to represent a view, the crumb tree is determined from the urls map
of your project, their titles and links are determined from the associated view entries in the breadcrumbs
registry.

Requires
********

Since the **0.9** version, it requires at least Django 1.5, for Django 1.4 you
will have to use the **0.8.1.1**, you can find him in the github releases.

Links
*****

* Download his `PyPi package <http://pypi.python.org/pypi/autobreadcrumbs>`_;
* Clone it on his `Github repository <https://github.com/sveetch/autobreadcrumbs>`_;

Install
=======

In your *settings* file add **AutoBreadcrumbs** to your installed apps :

::

    INSTALLED_APPS = (
        ...
        'autobreadcrumbs',
        ...
    )

Import default settings: ::

    from autobreadcrumbs.settings import *

Then register his *context processor* :

::

    TEMPLATE_CONTEXT_PROCESSORS = (
        ...
        'autobreadcrumbs.context_processors.AutoBreadcrumbsContext',
        ...
    )

And finally, as for the *autodiscover* for the admin site
(``django.contrib.admin``), you will have to add these two lines in your
``urls.py`` project :

::

    import autobreadcrumbs
    autobreadcrumbs.autodiscover()

This is optional but if you don't do this, all ``crumbs.py`` file will be
ignored and only titles defined in ``settings.AUTOBREADCRUMBS_TITLES`` will be used.

Usage
=====

Note that this app will don't work correctly if you don't have a strong organisation in your
urls map.

* You must ensure that all your urls are correctly named (see
  `Naming URL patterns <https://docs.djangoproject.com/en/dev/topics/http/urls/#naming-url-patterns>`_);
* Different views must not use the same url;
* If you use url namespace, prefix all your crumb url name with it;
* Regroup your restricted views on some url paths and don't mix them with non-restricted view urls.

View registration
*****************

Registration
------------

The *context processor* makes a search from the current url that is splitted in segments which represent
the crumbs. For each segment, an entry is searched on his URL name in the breadcrumbs registry in this
step order :

#. If the name has an entry in ``settings.AUTOBREADCRUMBS_TITLES``, then use it;
#. If the name has an entry in a ``crumbs.py`` file in one of your apps, then use it;

If none of these steps succeeds to find the URL name, the ressource will be ignored and not be displayed
in the breadcrumbs.

If you need to *hide* a ressource from breadcrumbs, just set his URL name to a *None* value, this will act in
ignoring the ressource.

A crumb title value use the Django template system to be rendered and is aware of the context of the template
where it is called, so you can use all available template filters, tags and variables in your crumb titles.

Optionally a crumb entry can be a tuple containing the title and callable
function : ::

        'documents-private-doc': (ugettext_lazy('Sitemap'), lambda x,y: True),

The callable function is given two arguments, the url name and the Request
object. The callable must return a boolean, ``True`` if the crumb can be
displayed or ``False`` if the crumb must be ignored.

This form is generally used to check permission for private views, like this : ::

    def check_crumb_perm(name, request):
        if name == 'documents-private-doc' and request.user.is_anonymous():
            return False
        return True

    AUTOBREADCRUMBS_TITLES = {
        ...
        'documents-private-doc': (ugettext_lazy('Sitemap'), lambda x,y: True),
        ...
    }

App crumbs
~~~~~~~~~~

Applications should define their crumbs in a ``crumbs.py`` file like this :

::

    from autobreadcrumbs import site
    from django.utils.translation import ugettext_lazy

    site.update({
        ...
        'documents-index': ugettext_lazy('Sitemap'),
        ...
    })

Note the usage of ``ugettext_lazy`` to get translated strings, if you don't use the `Django internationalization system`_ in your
project you can avoid it, but if you plan to use it you must apply ``ugettext_lazy`` on your title strings.

Project crumbs
~~~~~~~~~~~~~~

Also you can register crumbs in your project settings :

::

    AUTOBREADCRUMBS_TITLES = {
        "pages-index1": u"My index",
        "pages-index2": u"My index alternative",
    }

Crumbs setted in project settings have the higher priority on application crumbs. As for `App crumbs`_ you should use
``ugettext_lazy`` on your title strings.

Crumbs with URL namespace
~~~~~~~~~~~~~~~~~~~~~~~~~

If you use URL namespace on some views, remember to prefixed their crumb's url name with the namespace followed by a colon character, like this : ::

    AUTOBREADCRUMBS_TITLES = {
        ...
        "mynamespace:pages-index1": u"My index",
        ...
    }

If you forget to do this, your crumb won't be finded or be filled with a wrong crumb (from an another app view with the same url name but without the namespace).


Template context
****************

In all your templates laying that have the global context, two additional variables (`autobreadcrumbs_elements`_ and
`autobreadcrumbs_current`_) will be added by the *context processor*.

autobreadcrumbs_elements
------------------------

This variable will contain the breadcrumb as a list of crumbs in the correct order, where each crumb will be
a ``BreadcrumbRessource`` instance. A ``BreadcrumbRessource`` instance contains the following attributes :

* ``path`` : relative path to the ressource URL;
* ``name`` : the ressource name (that is the name of the URL linked to the ressource), prefixed with the namespace if any;
* ``title`` : the ressource title to be displayed;
* ``view_args`` : argument list given to the ressource view;
* ``view_kwargs`` : named argument list given to the ressource view;

autobreadcrumbs_current
-----------------------

This variable will contains the ``BreadcrumbRessource`` instance of the current crumb, this instance is the same as
the last list item in the `autobreadcrumbs_elements`_.

Template tags
*************

These tags are avalaible after loading their library in your templates : ::

    {% load autobreadcrumb %}

current_title_from_breadcrumbs
  This simply returns the title from the current ressource.
autobreadcrumbs_tag
  Builds the breadcrumb HTML using the ``autobreadcrumbs_tag.html`` template.
autobreadcrumbs_links
  Builds the breadcrumb HTML using the template strings in ``settings.AUTOBREADCRUMBS_HTML_LINK`` and
  ``settings.AUTOBREADCRUMBS_HTML_SEPARATOR``.
currentwalkthroughto
  Returns the content tag if the current ressource walk through the given ressource URL name.

  Example : ::

      {% currentwalkthroughto 'index' %}This pas walk through the named url 'index'{% endcurrentwalkthroughto %}

  If the test fail, the tag return an empty string.