Add DjangoModelPermissionsOrAnonReadOnly

docs/api-guide/permissions.md

@@ -97,15 +97,14 @@ This permission class ties into Django's standard `django.contrib.auth` [model p
 * `PUT` and `PATCH` requests require the user to have the `change` permission on the model.
 * `DELETE` requests require the user to have the `delete` permission on the model.
 
-If you want to use `DjangoModelPermissions` but also allow unauthenticated users to have read permission, override the class and set the `authenticated_users_only` property to `False`.  For example:
-
-    class HasModelPermissionsOrReadOnly(DjangoModelPermissions):
-        authenticated_users_only = False
-
 The default behaviour can also be overridden to support custom model permissions.  For example, you might want to include a `view` model permission for `GET` requests.
 
 To use custom model permissions, override `DjangoModelPermissions` and set the `.perms_map` property.  Refer to the source code for details.
 
+## DjangoModelPermissionsOrAnonReadOnly
+
+Similar to `DjangoModelPermissions`, but also allows unauthenticated users to have  read-only access to the API.
+
 ## TokenHasReadWriteScope
 
 This permission class is intended for use with either of the `OAuthAuthentication` and `OAuth2Authentication` classes, and ties into the scoping that their backends provide.

rest_framework/permissions.py

@@ -89,8 +89,8 @@ class DjangoModelPermissions(BasePermission):
     It ensures that the user is authenticated, and has the appropriate
     `add`/`change`/`delete` permissions on the model.
 
-    This permission will only be applied against view classes that
-    provide a `.model` attribute, such as the generic class-based views.
+    This permission can only be applied against view classes that
+    provide a `.model` or `.queryset` attribute.
     """
 
     # Map methods into required permission codes.
@@ -138,6 +138,14 @@ class DjangoModelPermissions(BasePermission):
         return False
 
 
+class DjangoModelPermissionsOrAnonReadOnly(DjangoModelPermissions):
+    """
+    Similar to DjangoModelPermissions, except that anonymous users are
+    allowed read-only access.
+    """
+    authenticated_users_only = False
+
+
 class TokenHasReadWriteScope(BasePermission):
     """
     The request is authenticated as a user and the token used has the right scope