Add a can_choose_root flag to PageChooserPanel.

This restores the previous behaviour, since there are plausible scenarios where choosing the root might be appropriate.

docs/reference/pages/panels.rst

@@ -94,7 +94,7 @@ FieldRowPanel
 PageChooserPanel
 ----------------
 
-.. class:: PageChooserPanel(field_name, page_type=None)
+.. class:: PageChooserPanel(field_name, page_type=None, can_choose_root=False)
 
     You can explicitly link :class:`~wagtail.wagtailcore.models.Page`-derived models together using the :class:`~wagtail.wagtailcore.models.Page` model and ``PageChooserPanel``.
 
@@ -117,10 +117,13 @@ PageChooserPanel
                 PageChooserPanel('related_page', 'demo.PublisherPage'),
             ]
 
-    ``PageChooserPanel`` takes two arguments: a field name and an optional page type. Specifying a page type (in the form of an ``"appname.modelname"`` string) will filter the chooser to display only pages of that type. A list or tuple of page types can also be passed in, to allow choosing a page that matches any of those page types::
+    ``PageChooserPanel`` takes one required argument, the field name. Optionally, specifying a page type (in the form of an ``"appname.modelname"`` string) will filter the chooser to display only pages of that type. A list or tuple of page types can also be passed in, to allow choosing a page that matches any of those page types::
 
         PageChooserPanel('related_page', ['demo.PublisherPage', 'demo.AuthorPage'])
 
+    Passing ``can_choose_root=True`` will allow the editor to choose the tree root as a page. Normally this would be undesirable, since the tree root is never a usable page, but in some specialised cases it may be appropriate; for example, a page with an automatic "related articles" feed could use a PageChooserPanel to select which subsection articles will be taken from, with the root corresponding to 'everywhere'.
+
+
 ImageChooserPanel
 -----------------
 

wagtail/wagtailadmin/edit_handlers.py

@@ -552,7 +552,7 @@ class BasePageChooserPanel(BaseChooserPanel):
     @classmethod
     def widget_overrides(cls):
         return {cls.field_name: widgets.AdminPageChooser(
-            content_type=cls.target_content_type())}
+            content_type=cls.target_content_type(), can_choose_root=cls.can_choose_root)}
 
     @classmethod
     def target_content_type(cls):
@@ -579,7 +579,7 @@ class BasePageChooserPanel(BaseChooserPanel):
 
 
 class PageChooserPanel(object):
-    def __init__(self, field_name, page_type=None):
+    def __init__(self, field_name, page_type=None, can_choose_root=False):
         self.field_name = field_name
 
         if page_type:
@@ -590,12 +590,14 @@ class PageChooserPanel(object):
             page_type = []
 
         self.page_type = page_type
+        self.can_choose_root = can_choose_root
 
     def bind_to_model(self, model):
         return type(str('_PageChooserPanel'), (BasePageChooserPanel,), {
             'model': model,
             'field_name': self.field_name,
             'page_type': self.page_type,
+            'can_choose_root': self.can_choose_root,
         })
 
 

wagtail/wagtailadmin/tests/test_edit_handlers.py

@@ -370,6 +370,20 @@ class TestPageChooserPanel(TestCase):
 
         self.assertIn(expected_js, result)
 
+    def test_render_js_init_with_can_choose_root_true(self):
+        # construct an alternative page chooser panel object, with can_choose_root=True
+        MyPageChooserPanel = PageChooserPanel('page', can_choose_root=True).bind_to_model(PageChooserModel)
+        PageChooserForm = MyPageChooserPanel.get_form_class(PageChooserModel)
+
+        form = PageChooserForm(instance=self.test_instance)
+        page_chooser_panel = MyPageChooserPanel(instance=self.test_instance, form=form)
+        result = page_chooser_panel.render_as_field()
+
+        # the canChooseRoot flag on createPageChooser should now be true
+        expected_js = 'createPageChooser("{id}", ["{model}"], {parent}, true);'.format(
+            id="id_page", model="wagtailcore.page", parent=self.events_index_page.id)
+        self.assertIn(expected_js, result)
+
     def test_get_chosen_item(self):
         result = self.page_chooser_panel.get_chosen_item()
         self.assertEqual(result, self.christmas_page)