Refs #24121 -- Added __repr__() to AdminSite, DefaultAdminSite, and ModelAdmin.

Thanks tlebrize for the initial patch.

django/contrib/admin/options.py

@@ -594,6 +594,12 @@ class ModelAdmin(BaseModelAdmin):
     def __str__(self):
         return "%s.%s" % (self.model._meta.app_label, self.__class__.__name__)
 
+    def __repr__(self):
+        return (
+            f'<{self.__class__.__qualname__}: model={self.model.__qualname__} '
+            f'site={self.admin_site!r}>'
+        )
+
     def get_inline_instances(self, request, obj=None):
         inline_instances = []
         for inline_class in self.get_inlines(request, obj):

django/contrib/admin/sites.py

@@ -77,6 +77,9 @@ class AdminSite:
         self._global_actions = self._actions.copy()
         all_sites.add(self)
 
+    def __repr__(self):
+        return f'{self.__class__.__name__}(name={self.name!r})'
+
     def check(self, app_configs):
         """
         Run the system checks on all ModelAdmins, except if they aren't
@@ -561,6 +564,9 @@ class DefaultAdminSite(LazyObject):
         AdminSiteClass = import_string(apps.get_app_config('admin').default_site)
         self._wrapped = AdminSiteClass()
 
+    def __repr__(self):
+        return repr(self._wrapped)
+
 
 # This global object represents the default admin site, for the common case.
 # You can provide your own AdminSite using the (Simple)AdminConfig.default_site