Start the page chooser at the most relevant page

Using the new `Page.objects.first_common_ancestor()`, page choosers that
are restricted to a certain page type start at the most relevant parent
page to make selecting a page easier.

wagtail/wagtailadmin/tests/test_page_chooser.py

@@ -298,6 +298,84 @@ class TestChooserSearch(TestCase, WagtailTestUtils):
         self.assertEqual(response.status_code, 404)
 
 
+class TestAutomaticRootPageDetection(TestCase, WagtailTestUtils):
+    def setUp(self):
+        self.tree_root = Page.objects.get(id=1)
+        self.home_page = Page.objects.get(id=2)
+
+        self.about_page = self.home_page.add_child(instance=SimplePage(
+            title='About', content='About Foo'))
+        self.contact_page = self.about_page.add_child(instance=SimplePage(
+            title='Contact', content='Content Foo'))
+        self.people_page = self.about_page.add_child(instance=SimplePage(
+            title='People', content='The people of Foo'))
+
+        self.event_index = self.make_event_section('Events')
+
+        self.login()
+
+    def make_event_section(self, name):
+        event_index = self.home_page.add_child(instance=EventIndex(
+            title=name))
+        event_index.add_child(instance=EventPage(
+            title='First Event',
+            location='Bar', audience='public',
+            cost='free', date_from='2001-01-01'))
+        event_index.add_child(instance=EventPage(
+            title='Second Event',
+            location='Baz', audience='public',
+            cost='free', date_from='2001-01-01'))
+        return event_index
+
+    def get_best_root(self, params={}):
+        response = self.client.get(reverse('wagtailadmin_choose_page'), params)
+        return response.context['parent_page'].specific
+
+    def test_no_type_filter(self):
+        self.assertEqual(self.get_best_root(), self.tree_root)
+
+    def test_type_page(self):
+        self.assertEqual(
+            self.get_best_root({'page_type': 'wagtailcore.Page'}),
+            self.tree_root)
+
+    def test_type_eventpage(self):
+        """
+        The chooser should start at the EventIndex that holds all the
+        EventPages.
+        """
+        self.assertEqual(
+            self.get_best_root({'page_type': 'tests.EventPage'}),
+            self.event_index)
+
+    def test_type_eventpage_two_indexes(self):
+        """
+        The chooser should start at the home page, as there are two
+        EventIndexes with EventPages.
+        """
+        self.make_event_section('Other events')
+        self.assertEqual(
+            self.get_best_root({'page_type': 'tests.EventPage'}),
+            self.home_page)
+
+    def test_type_simple_page(self):
+        """
+        The chooser should start at the home page, as all SimplePages are
+        directly under it
+        """
+        self.assertEqual(
+            self.get_best_root({'page_type': 'tests.BusinessIndex'}),
+            self.tree_root)
+
+    def test_type_missing(self):
+        """
+        The chooser should start at the root, as there are no BusinessIndexes
+        """
+        self.assertEqual(
+            self.get_best_root({'page_type': 'tests.BusinessIndex'}),
+            self.tree_root)
+
+
 class TestChooserExternalLink(TestCase, WagtailTestUtils):
     def setUp(self):
         self.login()

wagtail/wagtailadmin/views/chooser.py

@@ -51,32 +51,38 @@ def filter_page_type(queryset, page_models):
 
 
 def browse(request, parent_page_id=None):
+    # A missing or empty page_type parameter indicates 'all page types'
+    # (i.e. descendants of wagtailcore.page)
+    page_type_string = request.GET.get('page_type') or 'wagtailcore.page'
+    try:
+        desired_classes = page_models_from_string(page_type_string)
+    except (ValueError, LookupError):
+        raise Http404
+
     # Find parent page
     if parent_page_id:
         parent_page = get_object_or_404(Page, id=parent_page_id)
-    else:
+    elif desired_classes == (Page,):
+        # Just use the root page
         parent_page = Page.get_first_root_node()
+    else:
+        # Find the highest common ancestor for the specific classes passed in
+        # In many cases, such as selecting an EventPage under an EventIndex,
+        # this will help the administrator find their page quicker.
+        all_desired_pages = filter_page_type(Page.objects.all(), desired_classes)
+        parent_page = all_desired_pages.first_common_ancestor()
 
     # Get children of parent page
     pages = parent_page.get_children()
 
     # Filter them by page type
-    # A missing or empty page_type parameter indicates 'all page types' (i.e. descendants of wagtailcore.page)
-    page_type_string = request.GET.get('page_type') or 'wagtailcore.page'
-    if page_type_string != 'wagtailcore.page':
-        try:
-            desired_classes = page_models_from_string(page_type_string)
-        except (ValueError, LookupError):
-            raise Http404
-
+    if desired_classes != (Page,):
         # restrict the page listing to just those pages that:
         # - are of the given content type (taking into account class inheritance)
         # - or can be navigated into (i.e. have children)
         choosable_pages = filter_page_type(pages, desired_classes)
         descendable_pages = pages.filter(numchild__gt=0)
         pages = choosable_pages | descendable_pages
-    else:
-        desired_classes = (Page, )
 
     can_choose_root = request.GET.get('can_choose_root', False)