syntactic sugar for get_page_modes: change it to a property called preview_modes and add a default_preview_mode helper

Conflicts:
	wagtail/wagtailadmin/views/pages.py

docs/building_your_site/djangodevelopers.rst

@@ -201,6 +201,7 @@ Properties:
 * status_string
 * subpage_types
 * indexed_fields
+* preview_modes
 
 Methods:
 
@@ -213,7 +214,6 @@ Methods:
 * get_descendants
 * get_siblings
 * search
-* get_page_modes
 * show_as_mode
 
 

docs/model_recipes.rst

@@ -190,10 +190,10 @@ Load Alternate Templates by Overriding get_template()
 
 
 
-Page Modes
-----------
+Preview Modes
+-------------
 
-get_page_modes
+preview_modes
 show_as_mode
 
 

wagtail/wagtailadmin/views/pages.py

@@ -230,7 +230,7 @@ def create(request, content_type_app_name, content_type_model_name, parent_page_
         'page_class': page_class,
         'parent_page': parent_page,
         'edit_handler': edit_handler,
-        'display_modes': page.get_page_modes(),
+        'display_modes': page.preview_modes,
         'form': form, # Used in unit tests
     })
 
@@ -361,7 +361,7 @@ def edit(request, page_id):
         'page': page,
         'edit_handler': edit_handler,
         'errors_debug': errors_debug,
-        'display_modes': page.get_page_modes(),
+        'display_modes': page.preview_modes,
         'form': form, # Used in unit tests
     })
 
@@ -409,12 +409,8 @@ def preview_on_edit(request, page_id):
     if form.is_valid():
         form.save(commit=False)
 
-        try:
-            display_mode = request.GET['mode']
-        except KeyError:
-            display_mode = page.get_page_modes()[0][0]
-
-        response = page.show_as_mode(display_mode)
+        preview_mode = request.GET.get('mode', page.default_preview_mode)
+        response = page.show_as_mode(preview_mode)
 
         response['X-Wagtail-Preview'] = 'ok'
         return response
@@ -425,7 +421,7 @@ def preview_on_edit(request, page_id):
         response = render(request, 'wagtailadmin/pages/edit.html', {
             'page': page,
             'edit_handler': edit_handler,
-            'display_modes': page.get_page_modes(),
+            'display_modes': page.preview_modes,
         })
         response['X-Wagtail-Preview'] = 'error'
         return response
@@ -458,11 +454,8 @@ def preview_on_create(request, content_type_app_name, content_type_model_name, p
         page.depth = parent_page.depth + 1
         page.path = Page._get_children_path_interval(parent_page.path)[1]
 
-        try:
-            display_mode = request.GET['mode']
-        except KeyError:
-            display_mode = page.get_page_modes()[0][0]
-        response = page.show_as_mode(display_mode)
+        preview_mode = request.GET.get('mode', page.default_preview_mode)
+        response = page.show_as_mode(preview_mode)
 
         response['X-Wagtail-Preview'] = 'ok'
         return response
@@ -476,7 +469,7 @@ def preview_on_create(request, content_type_app_name, content_type_model_name, p
             'page_class': page_class,
             'parent_page': parent_page,
             'edit_handler': edit_handler,
-            'display_modes': page.get_page_modes(),
+            'display_modes': page.preview_modes,
         })
         response['X-Wagtail-Preview'] = 'error'
         return response

wagtail/wagtailcore/models.py

@@ -706,19 +706,28 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, Indexed)):
                                 "request middleware returned a response")
         return request
 
-    def get_page_modes(self):
+    @property
+    def preview_modes(self):
         """
-        Return a list of (internal_name, display_name) tuples for the modes in which
+        A list of (internal_name, display_name) tuples for the modes in which
         this page can be displayed for preview/moderation purposes. Ordinarily a page
         will only have one display mode, but subclasses of Page can override this -
         for example, a page containing a form might have a default view of the form,
         and a post-submission 'thankyou' page
         """
+        return self.get_page_modes()
+
+    def get_page_modes(self):
+        # Deprecated accessor for the preview_modes property
         return [('', 'Default')]
 
+    @property
+    def default_preview_mode(self):
+        return self.preview_modes[0][0]
+
     def show_as_mode(self, mode_name):
         """
-        Given an internal name from the get_page_modes() list, return an HTTP response
+        Given an internal name from the preview_modes list, return an HTTP response
         indicative of the page being viewed in that mode. By default this passes a
         dummy request into the serve() mechanism, ensuring that it matches the behaviour
         on the front-end; subclasses that define additional page modes will need to

wagtail/wagtailforms/models.py

@@ -170,11 +170,10 @@ class AbstractForm(Page):
             'form': form,
         })
 
-    def get_page_modes(self):
-        return [
-            ('form', 'Form'),
-            ('landing', 'Landing page'),
-        ]
+    preview_modes = [
+        ('form', 'Form'),
+        ('landing', 'Landing page'),
+    ]
 
     def show_as_mode(self, mode):
         if mode == 'landing':