Fixed #26951 -- Allowed AuthenticationForm to work with a username of 0.

django/contrib/auth/forms.py

@@ -186,7 +186,7 @@ class AuthenticationForm(forms.Form):
         username = self.cleaned_data.get('username')
         password = self.cleaned_data.get('password')
 
-        if username and password:
+        if username is not None and password:
             self.user_cache = authenticate(username=username, password=password)
             if self.user_cache is None:
                 raise forms.ValidationError(

tests/auth_tests/models/__init__.py

@@ -6,9 +6,10 @@ from .invalid_models import CustomUserNonUniqueUsername
 from .is_active import IsActiveTestUser1
 from .uuid_pk import UUIDUser
 from .with_foreign_key import CustomUserWithFK, Email
+from .with_integer_username import IntegerUsernameUser
 
 __all__ = (
     'CustomUser', 'CustomUserWithoutIsActiveField', 'CustomPermissionsUser',
     'CustomUserWithFK', 'Email', 'ExtensionUser', 'IsActiveTestUser1',
-    'UUIDUser', 'CustomUserNonUniqueUsername',
+    'UUIDUser', 'CustomUserNonUniqueUsername', 'IntegerUsernameUser'
 )

tests/auth_tests/models/with_integer_username.py

@@ -0,0 +1,23 @@
+from django.contrib.auth.models import AbstractBaseUser, BaseUserManager
+from django.db import models
+
+
+class IntegerUsernameUserManager(BaseUserManager):
+    def create_user(self, username, password):
+        user = self.model(username=username)
+        user.set_password(password)
+        user.save(using=self._db)
+        return user
+
+    def get_by_natural_key(self, username):
+        return self.get(username=username)
+
+
+class IntegerUsernameUser(AbstractBaseUser):
+    username = models.IntegerField()
+    password = models.CharField(max_length=255)
+
+    USERNAME_FIELD = 'username'
+    REQUIRED_FIELDS = ['username', 'password']
+
+    objects = IntegerUsernameUserManager()

tests/auth_tests/test_forms.py

@@ -15,7 +15,7 @@ from django.contrib.auth.models import User
 from django.contrib.sites.models import Site
 from django.core import mail
 from django.core.mail import EmailMultiAlternatives
-from django.forms.fields import CharField, Field
+from django.forms.fields import CharField, Field, IntegerField
 from django.test import SimpleTestCase, TestCase, mock, override_settings
 from django.utils import six, translation
 from django.utils.encoding import force_text
@@ -23,6 +23,7 @@ from django.utils.text import capfirst
 from django.utils.translation import ugettext as _
 
 from .models.custom_user import CustomUser, ExtensionUser
+from .models.with_integer_username import IntegerUsernameUser
 from .settings import AUTH_TEMPLATES
 
 
@@ -351,6 +352,23 @@ class AuthenticationFormTest(TestDataMixin, TestCase):
         form.is_valid()  # Not necessary to have valid credentails for the test.
         self.assertEqual(form.cleaned_data['password'], data['password'])
 
+    @override_settings(AUTH_USER_MODEL='auth_tests.IntegerUsernameUser')
+    def test_integer_username(self):
+        class CustomAuthenticationForm(AuthenticationForm):
+            username = IntegerField()
+
+        user = IntegerUsernameUser.objects.create_user(username=0, password='pwd')
+        data = {
+            'username': 0,
+            'password': 'pwd',
+        }
+        form = CustomAuthenticationForm(None, data)
+        self.assertTrue(form.is_valid())
+        self.assertEqual(form.cleaned_data['username'], data['username'])
+        self.assertEqual(form.cleaned_data['password'], data['password'])
+        self.assertEqual(form.errors, {})
+        self.assertEqual(form.user_cache, user)
+
 
 class SetPasswordFormTest(TestDataMixin, TestCase):