Fixed #9602 -- Added AdminSite.get_model_admin().

This allows retrieving an admin class for the given model class without
using internal attributes.

1 files changed, 24 insertions, 13 deletions

diff --git a/django/contrib/admin/options.py b/django/contrib/admin/options.py
index b0635669e9..f9760664dd 100644
--- a/django/contrib/admin/options.py
+++ b/django/contrib/admin/options.py
@@ -160,6 +160,8 @@ class BaseModelAdmin(metaclass=forms.MediaDefiningClass):
 
         If kwargs are given, they're passed to the form Field's constructor.
         """
+        from django.contrib.admin.sites import NotRegistered
+
         # If the field specifies choices, we don't need to look for special
         # admin widgets - we just need to use a select widget of some kind.
         if db_field.choices:
@@ -185,23 +187,27 @@ class BaseModelAdmin(metaclass=forms.MediaDefiningClass):
             # rendered output. formfield can be None if it came from a
             # OneToOneField with parent_link=True or a M2M intermediary.
             if formfield and db_field.name not in self.raw_id_fields:
-                related_modeladmin = self.admin_site._registry.get(
-                    db_field.remote_field.model
-                )
-                wrapper_kwargs = {}
-                if related_modeladmin:
-                    wrapper_kwargs.update(
-                        can_add_related=related_modeladmin.has_add_permission(request),
-                        can_change_related=related_modeladmin.has_change_permission(
+                try:
+                    related_modeladmin = self.admin_site.get_model_admin(
+                        db_field.remote_field.model
+                    )
+                except NotRegistered:
+                    wrapper_kwargs = {}
+                else:
+                    wrapper_kwargs = {
+                        "can_add_related": related_modeladmin.has_add_permission(
                             request
                         ),
-                        can_delete_related=related_modeladmin.has_delete_permission(
+                        "can_change_related": related_modeladmin.has_change_permission(
                             request
                         ),
-                        can_view_related=related_modeladmin.has_view_permission(
+                        "can_delete_related": related_modeladmin.has_delete_permission(
                             request
                         ),
-                    )
+                        "can_view_related": related_modeladmin.has_view_permission(
+                            request
+                        ),
+                    }
                 formfield.widget = widgets.RelatedFieldWidgetWrapper(
                     formfield.widget,
                     db_field.remote_field,
@@ -246,8 +252,13 @@ class BaseModelAdmin(metaclass=forms.MediaDefiningClass):
         ordering.  Otherwise don't specify the queryset, let the field decide
         (return None in that case).
         """
-        related_admin = self.admin_site._registry.get(db_field.remote_field.model)
-        if related_admin is not None:
+        from django.contrib.admin.sites import NotRegistered
+
+        try:
+            related_admin = self.admin_site.get_model_admin(db_field.remote_field.model)
+        except NotRegistered:
+            return None
+        else:
             ordering = related_admin.get_ordering(request)
             if ordering is not None and ordering != ():
                 return db_field.remote_field.model._default_manager.using(db).order_by(