id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
29449	UserCreationForm and UserChangeForm don't work if username isn't a CharField	Sławek Ehlert	nobody	"In 3333d935d2914cd80cf31f4803821ad5c0e2a51d (part of #28757 ticket) {{{UserCreationForm}}} (and by extension also {{{UserChangeForm}}}) was adjusted to support custom user models without overriding the form. The problem is that the implementation there assumes that the {{{USERNAME_FIELD}}} has to be a subclass of {{{CharField}}} since it uses {{{UsernameField}}} in the {{{field_classes}}} mapping.

Now to the fun part. Django already has some tests that should fail in such case (for example see https://github.com/django/django/blob/825f0beda804e48e9197fcf3b0d909f9f548aa47/tests/auth_tests/test_management.py#L435-L491), but the failure is actually ""swallowed"" when running the whole test suite. When running those tests individually we can see the failure.
Tim Graham already noticed something similar in https://code.djangoproject.com/ticket/28757#comment:7.
I.e.
{{{
 ./runtests.py auth_tests
}}} 
works, but 
{{{
./runtests.py auth_tests.test_management.CreatesuperuserManagementCommandTestCase.test_fields_with_fk
}}}
doesn't. I'm not sure why the failure is hidden in the former case (I suspect it has to do something with the {{{override_settings}}} decorator and {{{importlib.reload}}}ing done in the {{{reload_auth_forms}}} function from the commit I've mentioned). The stacktrace from the latter case looks like this:
{{{
ERROR: test_fields_with_fk (auth_tests.test_management.CreatesuperuserManagementCommandTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File ""/Users/slafs/testing/django/django/django/test/utils.py"", line 364, in inner
    with self as context:
  File ""/Users/slafs/testing/django/django/django/test/utils.py"", line 336, in __enter__
    return self.enable()
  File ""/Users/slafs/testing/django/django/django/test/utils.py"", line 405, in enable
    setting=key, value=new_value, enter=True)
  File ""/Users/slafs/testing/django/django/django/dispatch/dispatcher.py"", line 175, in send
    for receiver in self._live_receivers(sender)
  File ""/Users/slafs/testing/django/django/django/dispatch/dispatcher.py"", line 175, in <listcomp>
    for receiver in self._live_receivers(sender)
  File ""/Users/slafs/testing/django/django/django/test/signals.py"", line 195, in user_model_swapped
    from django.contrib.auth import forms
  File ""/Users/slafs/testing/django/django/django/contrib/auth/forms.py"", line 63, in <module>
    class UserCreationForm(forms.ModelForm):
  File ""/Users/slafs/testing/django/django/django/forms/models.py"", line 256, in __new__
    apply_limit_choices_to=False,
  File ""/Users/slafs/testing/django/django/django/forms/models.py"", line 172, in fields_for_model
    formfield = f.formfield(**kwargs)
  File ""/Users/slafs/testing/django/django/django/db/models/fields/related.py"", line 956, in formfield
    **kwargs,
  File ""/Users/slafs/testing/django/django/django/db/models/fields/related.py"", line 418, in formfield
    return super().formfield(**defaults)
  File ""/Users/slafs/testing/django/django/django/db/models/fields/__init__.py"", line 890, in formfield
    return form_class(**defaults)
  File ""/Users/slafs/testing/django/django/django/forms/fields.py"", line 213, in __init__
    super().__init__(**kwargs)
TypeError: __init__() got an unexpected keyword argument 'limit_choices_to'
}}}

Since {{{auth_tests.CustomUserWithFK}}} model uses a {{{ForeignKey}}} as a {{{USERNAME_FIELD}}}, the instantiation of {{{django.contrib.auth.forms.UsernameField}}} is failing. However, that test is a bit implicit as I'm not entirely sure why Django imports {{{UserCreationForm}}} in the first place (the stacktrace makes me think it's because of the signal mechanisms).

I'd suggest the following steps to go forward with this:

1) Write a more explicit regression test in {{{auth_tests.test_forms}}} that's using {{{auth_tests.CustomUserWithFK}}} as a user model (I'll try to do that).
2) Make adjustments in {{{auth_tests.test_forms}}} so that the mentioned tests will actually fail even when running the whole test suite (I think Tim Graham already tried this in https://code.djangoproject.com/ticket/28757#comment:8).
3) Fix {{{UserCreationForm}}} so it supports different types of fields for {{{USERNAME_FIELD}}}.

In my humble opinion this is a release blocker (I haven't marked this ticket as such, though)."	Bug	closed	contrib.auth	2.1	Release blocker	fixed	auth forms UserCreationForm UserChangeForm	markush Carlton Gibson Mariusz Felisiak	Accepted	0	0	0	0	0	0