[1.5.x] Fixed #19662 -- alter auth modelbackend to accept custom username fields

Thanks to Aymeric and Carl for the review.

1 files changed, 8 insertions, 2 deletions

diff --git a/docs/ref/contrib/auth.txt b/docs/ref/contrib/auth.txt
index 414f4558ee..b12c99fb91 100644
--- a/docs/ref/contrib/auth.txt
+++ b/docs/ref/contrib/auth.txt
@@ -417,9 +417,15 @@ The following backends are available in :mod:`django.contrib.auth.backends`:
 .. class:: ModelBackend
 
     This is the default authentication backend used by Django.  It
-    authenticates using usernames and passwords stored in the
-    :class:`~django.contrib.auth.models.User` model.
+    authenticates using credentials consisting of a user identifier and
+    password.  For Django's default user model, the user identifier is the
+    username, for custom user models it is the field specified by
+    USERNAME_FIELD (see :doc:`Customizing Users and authentication
+    </topics/auth/customizing>`).
 
+    It also handles the default permissions model as defined for
+    :class:`~django.contrib.auth.models.User` and
+    :class:`~django.contrib.auth.models.PermissionsMixin`.
 
 .. class:: RemoteUserBackend