Add ability to get breadcrumbs from menus

navbuilder/templates/navbuilder/inclusion_tags/breadcrumbs.html

@@ -0,0 +1,5 @@
+{% load navbuilder_tags %}
+{% for crumb in navbuilder_breadcrumbs %}
+<a class="Crumb" href="{{ crumb.link.get_absolute_url }}" title="{{ crumb.link.title|default:crumb.title }}" target="{{ crumb.target|default:"" }}" data-slug="{{ crumb.link.slug|default:crumb.slug }}">{{ crumb.link.title|default:crumb.title }}</a>
+{% if not forloop.last %} > {% endif %}
+{% endfor %}

navbuilder/templatetags/navbuilder_tags.py

@@ -1,6 +1,7 @@
 from django import template
+from django.contrib.contenttypes.models import ContentType
 
-from navbuilder.models import Menu
+from navbuilder.models import Menu, MenuItem
 
 register = template.Library()
 
@@ -22,3 +23,48 @@ def render_menu(context, slug):
 def render_menuitem(context, obj):
     context["object"] = obj
     return context
+
+
+@register.inclusion_tag(
+    "navbuilder/inclusion_tags/breadcrumbs.html", takes_context=True
+)
+def navbuilder_breadcrumbs(context, slug):
+    """
+    Render the breadcrumbs, based on the current object. Prefer using the
+    structure of the menu designated by slug, but use any menu available.
+    Typical use case for this would be if the main menu has an about/terms
+    page, but it's mirrored in the footer menu in a much flatter layout. We
+    prefer the main menu structure. This also allows us to construct
+    breadcrumbs for items that don't show up in page menus at all.
+    """
+    context["navbuilder_breadcrumbs"] = []
+    if "object" not in context:
+        return context
+
+    def get_menuitems(item):
+        if item.parent:
+            struct = get_menuitems(item.parent)
+            struct.append(item)
+            return struct
+        return [item]
+
+    content_type = ContentType.objects.get_for_model(context["object"])
+    crumb_sets = []
+    for item in MenuItem.objects.filter(
+            link_content_type__pk=content_type.id,
+            link_object_id = context["object"].id):
+
+        crumb_sets.append(get_menuitems(item))
+
+    for crumb_set in crumb_sets:
+        menu = crumb_set[0].menu
+        if menu and menu.slug == slug:
+            context["navbuilder_breadcrumbs"] = crumb_set
+
+    if not context["navbuilder_breadcrumbs"]:
+        if crumb_sets:
+            context["navbuilder_breadcrumbs"] = crumb_sets[0]
+        else:
+            context["navbuilder_breadcrumbs"] = []
+
+    return context

navbuilder/tests/test_base.py

@@ -37,3 +37,39 @@ def load_fixtures(kls):
     kls.sub_menuitem = models.MenuItem.objects.create(
         **kls.sub_menuitem_data
     )
+
+
+def load_crumb_fixtures(kls):
+    kls.menu_data_2 = {
+        "title": "Menu 2",
+        "slug": "menu-2"
+    }
+    kls.menu_2 = models.Menu.objects.create(**kls.menu_data_2)
+
+    kls.link_data_2 = {
+        "title": "Link 2",
+        "slug": "link-2",
+        "url": "/link/2/"
+    }
+    kls.link_2 = Link.objects.create(**kls.link_data_2)
+
+    kls.menuitem_data_2 = {
+        "title": "Menu Item 2",
+        "slug": "menu-item-2",
+        "position": 2,
+        "menu": kls.menu_2,
+        "link": kls.link
+    }
+    kls.menuitem_2 = models.MenuItem.objects.create(**kls.menuitem_data_2)
+
+    kls.sub_menuitem_data_2 = {
+        "title": "Sub Menu Item 2",
+        "slug": "sub-menu-item-2",
+        "position": 2,
+        "parent": kls.menuitem_2,
+        "target": "blank",
+        "link": None
+    }
+    kls.sub_menuitem_2 = models.MenuItem.objects.create(
+        **kls.sub_menuitem_data_2
+    )

navbuilder/tests/test_breadcrumbs.py

@@ -0,0 +1,75 @@
+from django.core.urlresolvers import reverse
+from django.test import TestCase
+from django.test.client import Client
+
+from navbuilder import models
+from navbuilder.tests.test_base import load_fixtures, load_crumb_fixtures
+
+from django.template import Context, Template
+
+crumb_template_1 = Template(
+        "{% load navbuilder_tags %}"
+        "{% navbuilder_breadcrumbs 'menu-1' %}"
+        )
+
+crumb_template_2 = Template(
+        "{% load navbuilder_tags %}"
+        "{% navbuilder_breadcrumbs 'menu-2' %}"
+        )
+
+crumb_template_3 = Template(
+        "{% load navbuilder_tags %}"
+        "{% navbuilder_breadcrumbs 'menu-3' %}"
+        )
+
+
+class BreadcrumbsTestCase(TestCase):
+    def setUp(self):
+        self.client = Client()
+        load_fixtures(self)
+        load_crumb_fixtures(self)
+        # Reorganise the items
+        self.menuitem.link = None
+        self.sub_menuitem_2.link = self.link
+
+
+    def test_single_level(self):
+        # The link object maps to a single level in menu 2
+        out = crumb_template_2.render(Context({"object": self.link}))
+        self.assertHTMLEqual(out, """
+                <a class="Crumb" href="/link/1/" title="Link 1"
+                target="" data-slug="link-1">
+                    Link 1
+                </a>
+                """
+                )
+
+    def test_multilevel(self):
+        # The link object maps to the submenu in menu 1
+        out = crumb_template_1.render(Context({"object": self.link}))
+        self.assertHTMLEqual(out, """
+                <a class="Crumb" href="/link/1/"
+                title="Link 1" target="" data-slug="link-1">
+                    Link 1
+                </a>
+                >
+                <a class="Crumb" data-slug="link-1" href="/link/1/"
+                target="blank" title="Link 1">
+                    Link 1
+                </a>
+                """
+                )
+
+    def test_menu_slug_not_found(self):
+        # If we cannot identify the menu it comes from, take the first one.
+        out = crumb_template_3.render(Context({"object": self.link}))
+        self.assertIn("Link 1", out)
+
+    def test_no_matching_menuitem(self):
+        # If the object does not show up in any menu, render nothing
+        self.menuitem_2.link = None
+        out = crumb_template_3.render(Context({"object": self.link_2}))
+        self.assertHTMLEqual("", out)
+
+    def tearDown(self):
+        pass