#32396: UsernameField normalisation throws TypeError if the username is empty
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Reporter: Łukasz Rzepa | Owner: nobody
Type: Bug | Status: new
Component: contrib.auth | Version: 3.1
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Hi guys, this is my first ticket so excuse me if it's not perfect.
I'm working on a project where we use custom `User` using `email` as a
`USERNAME_FIELD`. We allow users to have custom usernames but we don't
require them so `username` field has `null=True`.
While editing one of the staff users through the admin panel I've stumbled
upon an error when leaving the `username` field empty:
{{{
TypeError
normalize() argument 2 must be str, not None
}}}
To register `User` model to admin I'm using:
{{{
@admin.register(User)
class UserAdminView(UserAdmin):
add_fieldsets = (
(None, {
'classes': ('wide',),
'fields': ('email', 'password1', 'password2'),
}),
)
}}}
The source of the problem is the fact that `unicodedata.normalize()` in
{{{
class UsernameField(forms.CharField):
def to_python(self, value):
return unicodedata.normalize('NFKC', super().to_python(value))
}}}
needs a second argument to be a string. As `super().to_python(value)` is
actually `forms.CharField.to_python()` `''` value is returned as
`self.empty_value` with defaults to `''` but for a situation where
`CharField` has `null=True`. In this case it's determined in
`django.db.models.fields.CharField.formfield()` that
{{{
if self.null and not
connection.features.interprets_empty_strings_as_nulls:
defaults['empty_value'] = None
}}}
and our `self.empty_value` becomes `None` which is in effect passed to
normalize as a second argument.
My proposition is to fix it like this:
{{{
class UsernameField(forms.CharField):
def to_python(self, value):
value = super().to_python(value)
return None if value is None else unicodedata.normalize('NFKC',
value)
}}}
and allow the field null condition to be validated on the `model` level.
If you find this fix reasonable I'd be happy to open a PR with the
suggested change.
My project is using Django 2.2 but it's the same for 3.1.
--
Ticket URL: <https://code.djangoproject.com/ticket/32396>
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