Support media definitions on action menu items

docs/reference/hooks.rst

@@ -508,6 +508,7 @@ Hooks for customising the way users are directed through the process of creating
   :template: path to a template to render to produce the menu item HTML
   :get_context: a method that returns a context dictionary to pass to the template
   :render_html: a method that returns the menu item HTML; by default, renders ``template`` with the context returned from ``get_context``
+  :Media: an inner class defining Javascript and CSS to import when this menu item is shown - see `Django form media <https://docs.djangoproject.com/en/stable/topics/forms/media/>`_
 
   The ``get_url``, ``is_shown``, ``get_context`` and ``render_html`` methods all accept a request object and a context dictionary containing the following fields:
 

wagtail/admin/action_menu.py

@@ -1,14 +1,16 @@
 """Handles rendering of the list of actions in the footer of the page create/edit views."""
 
+from django.forms import Media, MediaDefiningClass
 from django.template.loader import render_to_string
 from django.urls import reverse
+from django.utils.functional import cached_property
 from django.utils.translation import ugettext_lazy as _
 
 from wagtail.core import hooks
 from wagtail.core.models import UserPagePermissionsProxy
 
 
-class ActionMenuItem:
+class ActionMenuItem(metaclass=MediaDefiningClass):
     """Defines an item in the actions drop-up on the page creation/edit view"""
     order = 100  # default order index if one is not specified on init
     template = 'wagtailadmin/pages/action_menu/menu_item.html'
@@ -162,3 +164,10 @@ class PageActionMenu:
                 for menu_item in self.menu_items
             ]
         }, request=self.request)
+
+    @cached_property
+    def media(self):
+        media = Media()
+        for item in self.menu_items:
+            media += item.media
+        return media

wagtail/admin/templates/wagtailadmin/pages/create.html

@@ -62,6 +62,7 @@
     {{ block.super }}
     {% include "wagtailadmin/pages/_editor_css.html" %}
     {{ edit_handler.form.media.css }}
+    {{ action_menu.media.css }}
 {% endblock %}
 
 {% block extra_js %}
@@ -72,6 +73,7 @@
         Additional js from widgets media. Allows for custom widgets in admin panel.
     {% endcomment %}
     {{ edit_handler.form.media.js }}
+    {{ action_menu.media.js }}
 
     {% comment %}
         Additional HTML code that edit handlers define through 'html_declarations'. (Technically this isn't Javascript, but it will generally be data that exists for Javascript to work with...)

wagtail/admin/templates/wagtailadmin/pages/edit.html

@@ -87,6 +87,7 @@
     {{ block.super }}
     {% include "wagtailadmin/pages/_editor_css.html" %}
     {{ edit_handler.form.media.css }}
+    {{ action_menu.media.css }}
 {% endblock %}
 
 {% block extra_js %}
@@ -97,6 +98,7 @@
         Additional js from widgets media. Allows for custom widgets in admin panel.
     {% endcomment %}
     {{ edit_handler.form.media.js }}
+    {{ action_menu.media.js }}
 
     {% comment %}
         Additional HTML code that edit handlers define through 'html_declarations'. (Technically this isn't Javascript, but it will generally be data that exists for Javascript to work with...)

wagtail/admin/tests/test_pages_views.py

@@ -665,6 +665,7 @@ class TestPageCreation(TestCase, WagtailTestUtils):
         self.assertContains(response, '<a href="#tab-promote" class="">Promote</a>')
         # test register_page_action_menu_item hook
         self.assertContains(response, '<input type="submit" name="action-panic" value="Panic!" class="button" />')
+        self.assertContains(response, 'testapp/js/siren.js')
         # test construct_page_action_menu hook
         self.assertContains(response, '<input type="submit" name="action-relax" value="Relax." class="button" />')
 
@@ -1280,6 +1281,7 @@ class TestPageEdit(TestCase, WagtailTestUtils):
 
         # test register_page_action_menu_item hook
         self.assertContains(response, '<input type="submit" name="action-panic" value="Panic!" class="button" />')
+        self.assertContains(response, 'testapp/js/siren.js')
 
         # test construct_page_action_menu hook
         self.assertContains(response, '<input type="submit" name="action-relax" value="Relax." class="button" />')

wagtail/tests/testapp/wagtail_hooks.py

@@ -111,6 +111,9 @@ class PanicMenuItem(ActionMenuItem):
     label = "Panic!"
     name = 'action-panic'
 
+    class Media:
+        js = ['testapp/js/siren.js']
+
 
 @hooks.register('register_page_action_menu_item')
 def register_panic_menu_item():