Improved error handling and docs for get_user_model()

django/contrib/auth/__init__.py

@@ -101,7 +101,10 @@ def get_user_model():
         app_label, model_name = settings.AUTH_USER_MODEL.split('.')
     except ValueError:
         raise ImproperlyConfigured("AUTH_USER_MODEL must be of the form 'app_label.model_name'")
-    return get_model(app_label, model_name)
+    user_model = get_model(app_label, model_name)
+    if user_model is None:
+        raise ImproperlyConfigured("AUTH_USER_MODEL refers to model '%s' that has not been installed" % settings.AUTH_USER_MODEL)
+    return user_model
 
 
 def get_user(request):

django/contrib/auth/tests/basic.py

@@ -1,10 +1,14 @@
 import locale
 
+from django.contrib.auth import get_user_model
 from django.contrib.auth.management.commands import createsuperuser
 from django.contrib.auth.models import User, AnonymousUser
+from django.contrib.auth.tests.custom_user import CustomUser
 from django.contrib.auth.tests.utils import skipIfCustomUser
+from django.core.exceptions import ImproperlyConfigured
 from django.core.management import call_command
 from django.test import TestCase
+from django.test.utils import override_settings
 from django.utils.six import StringIO
 
 
@@ -149,3 +153,24 @@ class BasicTestCase(TestCase):
         # If we were successful, a user should have been created
         u = User.objects.get(username="nolocale@somewhere.org")
         self.assertEqual(u.email, 'nolocale@somewhere.org')
+
+    def test_get_user_model(self):
+        "The current user model can be retrieved"
+        self.assertEqual(get_user_model(), User)
+
+    @override_settings(AUTH_USER_MODEL='auth.CustomUser')
+    def test_swappable_user(self):
+        "The current user model can be swapped out for another"
+        self.assertEqual(get_user_model(), CustomUser)
+
+    @override_settings(AUTH_USER_MODEL='badsetting')
+    def test_swappable_user_bad_setting(self):
+        "The alternate user setting must point to something in the format app.model"
+        with self.assertRaises(ImproperlyConfigured):
+            get_user_model()
+
+    @override_settings(AUTH_USER_MODEL='thismodel.doesntexist')
+    def test_swappable_user_nonexistent_model(self):
+        "The current user model must point to an installed model"
+        with self.assertRaises(ImproperlyConfigured):
+            get_user_model()

docs/topics/auth.txt

@@ -1791,7 +1791,7 @@ different User model.
 
 Instead of referring to :class:`~django.contrib.auth.models.User` directly,
 you should reference the user model using
-:meth:`~django.contrib.auth.get_user_model()`. This method will return the
+:func:`django.contrib.auth.get_user_model()`. This method will return the
 currently  active User model -- the custom User model if one is specified, or
 :class:`~django.contrib.auth.User` otherwise.