Fixed #19925 - Added validation for REQUIRED_FIELDS being a list

Thanks Roman Alexander for the suggestion.

AUTHORS

@@ -550,6 +550,7 @@ answer newbie questions, and generally made Django that much better:
     Thomas Steinacher <http://www.eggdrop.ch/>
     Emil Stenström <em@kth.se>
     Johan C. Stöver <johan@nilling.nl>
+    Chris Streeter <chris@chrisstreeter.com>
     Nowell Strite <http://nowell.strite.org/>
     Thomas Stromberg <tstromberg@google.com>
     Hannes Struß <x@hannesstruss.de>

django/contrib/auth/tests/test_custom_user.py

@@ -156,6 +156,18 @@ class CustomUserNonUniqueUsername(AbstractBaseUser):
         app_label = 'auth'
 
 
+class CustomUserNonListRequiredFields(AbstractBaseUser):
+    "A user with a non-list REQUIRED_FIELDS"
+    username = models.CharField(max_length=30, unique=True)
+    date_of_birth = models.DateField()
+
+    USERNAME_FIELD = 'username'
+    REQUIRED_FIELDS = 'date_of_birth'
+
+    class Meta:
+        app_label = 'auth'
+
+
 class CustomUserBadRequiredFields(AbstractBaseUser):
     "A user with a non-unique username"
     username = models.CharField(max_length=30, unique=True)

django/contrib/auth/tests/test_management.py

@@ -174,6 +174,13 @@ class CreatesuperuserManagementCommandTestCase(TestCase):
 
 
 class CustomUserModelValidationTestCase(TestCase):
+    @override_settings(AUTH_USER_MODEL='auth.CustomUserNonListRequiredFields')
+    def test_required_fields_is_list(self):
+        "REQUIRED_FIELDS should be a list."
+        new_io = StringIO()
+        get_validation_errors(new_io, get_app('auth'))
+        self.assertIn("The REQUIRED_FIELDS must be a list or tuple.", new_io.getvalue())
+
     @override_settings(AUTH_USER_MODEL='auth.CustomUserBadRequiredFields')
     def test_username_not_in_required_fields(self):
         "USERNAME_FIELD should not appear in REQUIRED_FIELDS."

django/core/management/validation.py

@@ -51,6 +51,10 @@ def get_validation_errors(outfile, app=None):
 
         # If this is the current User model, check known validation problems with User models
         if settings.AUTH_USER_MODEL == '%s.%s' % (opts.app_label, opts.object_name):
+            # Check that REQUIRED_FIELDS is a list
+            if not isinstance(cls.REQUIRED_FIELDS, (list, tuple)):
+                e.add(opts, 'The REQUIRED_FIELDS must be a list or tuple.')
+
             # Check that the USERNAME FIELD isn't included in REQUIRED_FIELDS.
             if cls.USERNAME_FIELD in cls.REQUIRED_FIELDS:
                 e.add(opts, 'The field named as the USERNAME_FIELD should not be included in REQUIRED_FIELDS on a swappable User model.')