Method clean_username

django/contrib/auth/forms.py:255–272

Reject usernames that differ only in case.

(self)

class UserCreationForm(BaseUserCreationForm):
    def clean_username(self):
        """Reject usernames that differ only in case."""
        username = self.cleaned_data.get("username")
        if (
            username
            and self._meta.model.objects.filter(username__iexact=username).exists()
        ):
            self._update_errors(
                ValidationError(
                    {
                        "username": self.instance.unique_error_message(
                            self._meta.model, ["username"]
                        )
                    }
                )
            )
        else:
            return username


class UserChangeForm(forms.ModelForm):