Warn if StreamField doesn't use StreamFieldPanel (#7276)

CHANGELOG.txt

@@ -11,6 +11,7 @@ Changelog
  * Added locale selector when choosing translatable snippets (Karl Hobley)
  * Added `WAGTAIL_WORKFLOW_ENABLED` setting for enabling / disabling moderation workflows globally (Matt Westcott)
  * Allow specifying `max_width` and `max_height` on EmbedBlock (Petr Dlouhý)
+ * Add warning when StreamField is used without a StreamFieldPanel (Naomi Morduch Toubman)
  * Fix: Invalid filter values for foreign key fields in the API now give an error instead of crashing (Tidjani Dia)
  * Fix: Ordering specified in `construct_explorer_page_queryset` hook is now taken into account again by the page explorer API (Andre Fonseca)
  * Fix: Deleting a page from its listing view no longer results in a 404 error (Tidjani Dia)

docs/releases/2.14.rst

@@ -19,6 +19,7 @@ Other features
  * Added locale selector when choosing translatable snippets (Karl Hobley)
  * Added ``WAGTAIL_WORKFLOW_ENABLED`` setting for enabling / disabling moderation workflows globally (Matt Westcott)
  * Allow specifying ``max_width`` and ``max_height`` on EmbedBlock (Petr Dlouhý)
+ * Add warning when StreamField is used without a StreamFieldPanel (Naomi Morduch Toubman)
 
 Bug fixes
 ~~~~~~~~~

wagtail/admin/checks.py

@@ -1,6 +1,7 @@
 import os
 
 from django.core.checks import Error, Warning, register
+from django.core.exceptions import FieldDoesNotExist
 
 
 @register()
@@ -151,3 +152,51 @@ There are no default tabs on non-Page models so there will be no \
         errors.append(error)
 
     return errors
+
+
+@register('panels')
+def panel_type_check(app_configs, **kwargs):
+    from wagtail.core.models import get_page_models
+
+    errors = []
+
+    for cls in get_page_models():
+        errors += traverse_edit_handlers(cls.get_edit_handler())
+
+    return errors
+
+
+def traverse_edit_handlers(edit_handler):
+    errors = []
+
+    try:
+        for child in edit_handler.children:
+            errors += traverse_edit_handlers(child)
+    except AttributeError:
+        error = check_stream_field_panel_type(edit_handler)
+        if error:
+            errors.append(error)
+
+    return errors
+
+
+def check_stream_field_panel_type(edit_handler):
+    from wagtail.admin.edit_handlers import StreamFieldPanel
+    from wagtail.core.fields import StreamField
+
+    try:
+        db_field = getattr(edit_handler, 'db_field', None)
+        if isinstance(db_field, StreamField) and not isinstance(edit_handler, StreamFieldPanel):
+            return Warning(
+                "{model}.{field_name} is a StreamField, but uses {edit_handler}".format(
+                    model=edit_handler.model.__name__,
+                    field_name=edit_handler.field_name,
+                    edit_handler=edit_handler.__class__.__name__),
+                hint="Ensure that it uses a StreamFieldPanel, or change the field type",
+                obj=edit_handler.model,
+                id='wagtailadmin.W003'
+            )
+    except FieldDoesNotExist:
+        # Doesn't check any fields not on the model, such as in
+        # wagtail.tests.testapp.modelsFormClassAdditionalFieldPage
+        pass

wagtail/admin/tests/test_edit_handlers.py

@@ -24,8 +24,8 @@ from wagtail.core.models import Comment, CommentReply, Page, Site
 from wagtail.images.edit_handlers import ImageChooserPanel
 from wagtail.tests.testapp.forms import ValidatedPageForm
 from wagtail.tests.testapp.models import (
-    EventPage, EventPageChooserModel, EventPageSpeaker, PageChooserModel, RestaurantPage,
-    RestaurantTag, SimplePage, ValidatedPage)
+    DefaultStreamPage, EventPage, EventPageChooserModel, EventPageSpeaker, PageChooserModel,
+    RestaurantPage, RestaurantTag, SimplePage, ValidatedPage)
 from wagtail.tests.utils import WagtailTestUtils
 
 
@@ -217,6 +217,28 @@ class TestPageEditHandlers(TestCase):
 
             self.assertEqual(errors, [invalid_base_form, invalid_edit_handler])
 
+    @clear_edit_handler(DefaultStreamPage)
+    def test_check_invalid_streamfield_edit_handler(self):
+        """
+        Set the edit handler for body (a StreamField) to be
+        a FieldPanel instead of a StreamFieldPanel.
+        Check that the correct warning is raised.
+        """
+
+        invalid_edit_handler = checks.Warning(
+            "DefaultStreamPage.body is a StreamField, but uses FieldPanel",
+            hint="Ensure that it uses a StreamFieldPanel, or change the field type",
+            obj=DefaultStreamPage,
+            id='wagtailadmin.W003')
+
+        with mock.patch.object(DefaultStreamPage, 'content_panels', new=[FieldPanel('body')]):
+            checks_result = checks.run_checks(tags=['panels'])
+
+            # Only look at warnings for DefaultStreamPage
+            warning = [warning for warning in checks_result if warning.obj == DefaultStreamPage]
+
+            self.assertEqual(warning, [invalid_edit_handler])
+
     @clear_edit_handler(ValidatedPage)
     def test_custom_edit_handler_form_class(self):
         """