fix(passkeys): get actual identifier field (e.g. email) instead of username, to allow for custom user models

[ganiyevuz]

Fixed authentication backend crash when using custom username fields (e.g. email or phone). The backend now safely handles requests without the passkeys field and works correctly with any configured USERNAME_FIELD, avoiding exceptions during standard login flows. Additionally, username is passed as None when not provided to prevent unintended behavior in ModelBackend.authenticate.

https://github.com/django/django/blob/50bbf71bbd51616e2ce48785336ca3746fbe5f24/django/contrib/auth/backends.py#L66

[mkalioby]

@ganiyevuz , can you please provide an example User Model and usage to understand how this shall work.

[ganiyevuz]

class User(AbstractBaseUser, PermissionsMixin):

    class UserType(TextChoices):
        SUPERADMIN = "super", _("Super Admin")
        ADMIN = "admin", _("Admin")
        SUPPORT = "support", _("Support")

    first_name = CharField(_("first name"), max_length=150, blank=True)
    avatar = ImageField(
        validators=[
            FileExtensionValidator(allowed_extensions=["jpg", "jpeg", "png", "webp"]),
            validate_file_size,
        ],
        upload_to="avatars/", null=True, blank=True, verbose_name=_("avatar")
    )
    email = EmailField(
        _("email address"),
        unique=True,
        blank=False,
        error_messages={
            "unique": _("A user with that email already exists."),
        },
    )
    role = CharField(
        _("role"),
        max_length=20,
        choices=UserType.choices,
        default=UserType.SUPPORT,
        help_text=_("Role of the user in the system."),
    )
    is_staff = BooleanField(
        _("staff status"),
        default=False,
        help_text=_("Designates whether the user can log into this admin site."),
    )
    is_active = BooleanField(
        _("active"),
        default=True,
        help_text=_(
            "Designates whether this user should be treated as active. "
            "Unselect this instead of deleting accounts."
        ),
    )
    company = ForeignKey('companies.Company', on_delete=CASCADE, null=True, blank=True,
                         verbose_name=_("company"))
    notification_enabled = BooleanField(default=True)
    notification_sound_enabled = BooleanField(default=True)
    date_joined = DateTimeField(_("date joined"), auto_now_add=True)

    objects = UserManager()

    USERNAME_FIELD = "email"
    REQUIRED_FIELDS = []

    class Meta:
        verbose_name = _("user")
        verbose_name_plural = _("users")

as you can see there is no email field in my User model and instead i am using email so when i try to use im getting username as none because of actual identifier is in different field.

[mkalioby]

Done as published as v2.2b1.

pip install django-passkeys==2.2b1