register the handler only if usermodel lastlogin is a field register the handler only if usermodel last_login is a field
from django.apps import AppConfig
from django.core import checks
from django.db.models.query_utils import DeferredAttribute
from django.db.models.signals import post_migrate
from django.utils.translation import gettext_lazy as _

from . import get_user_model
from .checks import check_models_permissions, check_user_model
from .management import create_permissions
from .signals import user_logged_in


class AuthConfig(AppConfig):
    default_auto_field = "django.db.models.AutoField"
    name = "django.contrib.auth"
    verbose_name = _("Authentication and Authorization")

    def ready(self):
        post_migrate.connect(
            create_permissions,
            dispatch_uid="django.contrib.auth.management.create_permissions",
        )
        last_login_field = getattr(get_user_model(), "last_login", None)
        
        if isinstance(last_login_field, DeferredAttribute):
            from .models import update_last_login

            user_logged_in.connect(update_last_login, dispatch_uid="update_last_login")
        checks.register(check_user_model, checks.Tags.models)
        checks.register(check_models_permissions, checks.Tags.models)