Error about Django custom authentication and login?

Question

I create a custom Authentication backends for my login system. Surely, the custom backends works when I try it in python shell. However, I got error when I run it in the server. The error says "The following fields do not exist in this model or are m2m fields: last_login". Do I need include the last_login field in customer model or Is there any other solution to solve the problem? Here is my sample code:

In my models.py

class Customer(models.Model):

  yes_or_no = ((True, 'Yes'),(False, 'No'))
  male_or_female = ((True,'Male'),(False,'Female'))

  name = models.CharField(max_length=100)
  email = models.EmailField(max_length=100,blank = False, null = False)
  password = models.CharField(max_length=100)
  gender = models.BooleanField(default = True, choices = male_or_female)
  birthday = models.DateField(default =None,blank = False, null = False)
  created = models.DateTimeField(default=datetime.now, blank=True)
  _is_active = models.BooleanField(default = False,db_column="is_active")

  @property
  def is_active(self):
    return self._is_active
  # how to call setter method, how to pass value ?
  @is_active.setter
  def is_active(self,value):
    self._is_active = value

  def __str__(self):
    return self.name

In backends.py

from .models import Customer
from django.conf import settings

class CustomerAuthBackend(object):

    def authenticate(self, name=None, password=None):
        try:
            user = Customer.objects.get(name=name)

            if password == getattr(user,'password'):
                # Authentication success by returning the user
                user.is_active = True
                return user
            else:
                # Authentication fails if None is returned
                return None
        except Customer.DoesNotExist:
            return None

    def get_user(self, user_id):
        try:
            return Customer.objects.get(pk=user_id)
        except Customer.DoesNotExist:
            return None

In views.py

@login_required(login_url='/dataInfo/login/')
def login_view(request):
    if request.method == 'POST':

        username = request.POST['username']
        password = request.POST['password']
        user = authenticate(name=username,password=password)
        if user is not None:

            if user.is_active:
                login(request,user)
                #redirect to user profile
                print "suffcessful login!"
                return HttpResponseRedirect('/dataInfo/userprofile')
            else:
                # return a disable account
                return HttpResponse("User acount or password is incorrect")
        else:
            # Return an 'invalid login' error message.
            print "Invalid login details: {0}, {1}".format(username, password)
            # redirect to login page
            return HttpResponseRedirect('/dataInfo/login')
    else:

        login_form = LoginForm()
    return render_to_response('dataInfo/login.html', {'form': login_form}, context_instance=RequestContext(request))

In setting.py

AUTHENTICATION_BACKENDS = ('dataInfo.backends.CustomerAuthBackend', 'django.contrib.auth.backends.ModelBackend',)

How did you manage to solve it? Can you add your own answer? Also when I specify AUTH_USER_MODEL in the settings it fails. Did you omit it? Also is it necessary to makemigrations? — csandreas1
– csandreas1, Commented Jun 18, 2020 at 9:57

Mukesh Sai Kumar · Accepted Answer · 2021-07-05 15:36:31Z

8

This is happening because you are using django's login() function to log the user in.

Django's login function emits a signal named user_logged_in with the user instance you supplied as argument. See login() source.

And this signal is listened in django's contrib.auth.models. It tries to update a field named last_login assuming that the user instance you have supplied is a subclass of django's default AbstractUser model.

In order to fix this, you can do one of the following things:

Stop using the login() function shipped with django and create a custom one.
Disconnect the user_logged_in signal from update_last_login receiver. Read how.
Add a field named last_login to your model
Extend your model from django's base auth models. Read how

edited Jul 5, 2021 at 15:36

Mukesh Sai Kumar

1075 bronze badges

answered Jul 2, 2016 at 5:32

v1k45

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3 Comments

pipi Over a year ago

I add a last_login field in the Customer model, but the same error still exists.Do I do need to modify somewhere else?

v1k45 Over a year ago

Are you sure you've added it as a datetime field? Have you migrated your database?

pipi Over a year ago

Yes, I did. I realized that the field name must be exactly as "last_login", but I named it as private variable(_last_login) and this may be the reason to cause the issue.

Deep · Accepted Answer · 2020-10-14 09:55:55Z

Thanks, I defined a custom login method as follows to get through this issue in my automated tests in which I by default keep the signals off.

Here's a working code example.

def login(client: Client, user: User) -> None:
    """
    Disconnect the update_last_login signal and force_login as `user`
    Ref: https://stackoverflow.com/questions/38156681/error-about-django-custom-authentication-and-login
    Args:
        client: Django Test client instance to be used to login
        user: User object to be used to login
    """
    user_logged_in.disconnect(receiver=update_last_login)
    client.force_login(user=user)
    user_logged_in.connect(receiver=update_last_login)

This in turn is used in tests as follows:

class TestSomething(TestCase):
    """
    Scenarios to validate:
    ....
    """

    @classmethod
    @factory.django.mute_signals(signals.pre_save, signals.post_save)
    def setUpTestData(cls):
        """
        Helps keep tests execution time under control
        """

        cls.client = Client()
        cls.content_type = 'application/json'

    def test_a_scenario(self):
        """
        Scenario details...
        """
        login(client=self.client, user=<User object>)
        response = self.client.post(...)
        ...

Hope it helps.

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