Using the polymorphic inlines for Django admin instead of the regular one

src/personalisation/admin.py

@@ -1,15 +1,17 @@
 from django.contrib import admin
 
 from personalisation import models
+from polymorphic.admin import PolymorphicInlineSupportMixin, StackedPolymorphicInline
 
+class RulesInline(StackedPolymorphicInline):
 
-class TimeRuleAdminInline(admin.TabularInline):
+    class TimeRuleAdminInline(StackedPolymorphicInline.Child):
         """Inline the Time Rule into the administration interface for segments"""
         model = models.TimeRule
         extra = 0
 
 
-class ReferralRuleAdminInline(admin.TabularInline):
+    class ReferralRuleAdminInline(StackedPolymorphicInline.Child):
         """
         Inline the Referral Rule into the administration interface for segments
         """
@@ -17,7 +19,7 @@ class ReferralRuleAdminInline(admin.TabularInline):
         extra = 0
 
 
-class VisitCountRuleAdminInline(admin.TabularInline):
+    class VisitCountRuleAdminInline(StackedPolymorphicInline.Child):
         """
         Inline the Visit Count Rule into the administration interface for segments
         """
@@ -25,12 +27,14 @@ class VisitCountRuleAdminInline(admin.TabularInline):
         extra = 0
 
 
-class SegmentAdmin(admin.ModelAdmin):
-    """Add the inlines to the Segment admin interface"""
-    inlines = (
-        TimeRuleAdminInline, ReferralRuleAdminInline,
-        VisitCountRuleAdminInline
+    model = models.AbstractBaseRule
+    child_inlines = (
+        TimeRuleAdminInline,
+        ReferralRuleAdminInline,
+        VisitCountRuleAdminInline,
     )
 
 
-admin.site.register(models.Segment, SegmentAdmin)
+@admin.register(models.Segment)
+class SegmentAdmin(PolymorphicInlineSupportMixin, admin.ModelAdmin):
+    inlines = (RulesInline,)

src/personalisation/models.py

@@ -14,10 +14,9 @@ from modelcluster.fields import ParentalKey
 from modelcluster.models import ClusterableModel
 from polymorphic.models import PolymorphicModel
 from wagtail.utils.decorators import cached_classmethod
-from wagtail.wagtailadmin.edit_handlers import (FieldPanel, FieldRowPanel,
-                                                InlinePanel, MultiFieldPanel,
-                                                ObjectList, PageChooserPanel,
-                                                TabbedInterface)
+from wagtail.wagtailadmin.edit_handlers import (
+    FieldPanel, FieldRowPanel, InlinePanel, MultiFieldPanel, ObjectList,
+    PageChooserPanel, TabbedInterface)
 from wagtail.wagtailadmin.forms import WagtailAdminPageForm
 from wagtail.wagtailcore.models import Page
 
@@ -26,7 +25,7 @@ from wagtail.wagtailcore.models import Page
 class AbstractBaseRule(PolymorphicModel):
     """Base for creating rules to segment users with"""
     segment = ParentalKey(
-        'Segment',
+        'personalisation.Segment',
         # TODO: Make the related names accesible to wagtail admin
         # for inlining them.
         related_name="%(app_label)s_%(class)s_related",