Used AdminSite.is_registered() where appropriate.

django/contrib/admin/sites.py

@@ -120,7 +120,7 @@ class AdminSite:
                     % model.__name__
                 )
 
-            if model in self._registry:
+            if self.is_registered(model):
                 registered_admin = str(self._registry[model])
                 msg = "The model %s is already registered " % model.__name__
                 if registered_admin.endswith(".ModelAdmin"):
@@ -156,7 +156,7 @@ class AdminSite:
         if isinstance(model_or_iterable, ModelBase):
             model_or_iterable = [model_or_iterable]
         for model in model_or_iterable:
-            if model not in self._registry:
+            if not self.is_registered(model):
                 raise NotRegistered("The model %s is not registered" % model.__name__)
             del self._registry[model]
 

django/contrib/admin/utils.py

@@ -139,12 +139,11 @@ def get_deleted_objects(objs, request, admin_site):
 
     def format_callback(obj):
         model = obj.__class__
-        has_admin = model in admin_site._registry
         opts = obj._meta
 
         no_edit_link = "%s: %s" % (capfirst(opts.verbose_name), obj)
 
-        if has_admin:
+        if admin_site.is_registered(model):
             if not admin_site._registry[model].has_delete_permission(request, obj):
                 perms_needed.add(opts.verbose_name)
             try:

django/contrib/admin/widgets.py

@@ -145,7 +145,7 @@ class ForeignKeyRawIdWidget(forms.TextInput):
     def get_context(self, name, value, attrs):
         context = super().get_context(name, value, attrs)
         rel_to = self.rel.model
-        if rel_to in self.admin_site._registry:
+        if self.admin_site.is_registered(rel_to):
             # The related object is registered with the same AdminSite
             related_url = reverse(
                 "admin:%s_%s_changelist"
@@ -222,7 +222,7 @@ class ManyToManyRawIdWidget(ForeignKeyRawIdWidget):
 
     def get_context(self, name, value, attrs):
         context = super().get_context(name, value, attrs)
-        if self.rel.model in self.admin_site._registry:
+        if self.admin_site.is_registered(self.rel.model):
             # The related object is registered with the same AdminSite
             context["widget"]["attrs"]["class"] = "vManyToManyRawIdAdminField"
         return context
@@ -268,7 +268,7 @@ class RelatedFieldWidgetWrapper(forms.Widget):
         # Backwards compatible check for whether a user can add related
         # objects.
         if can_add_related is None:
-            can_add_related = rel.model in admin_site._registry
+            can_add_related = admin_site.is_registered(rel.model)
         self.can_add_related = can_add_related
         # XXX: The UX does not support multiple selected values.
         multiple = getattr(widget, "allow_multiple_selected", False)

tests/admin_ordering/tests.py

@@ -148,7 +148,7 @@ class TestRelatedFieldsAdminOrdering(TestCase):
 
     def tearDown(self):
         site.unregister(Song)
-        if Band in site._registry:
+        if site.is_registered(Band):
             site.unregister(Band)
 
     def check_ordering_of_field_choices(self, correct_ordering):