Django - get_by_natural_key() takes exactly 3 arguments (2 given)

Question

I'm trying to create a user log in. But when I go to log in I get the Error Message:

TypeError: get_by_natural_key() takes exactly 3 arguments (2 given)

There was a similar question asked before, but it never got resolved

I have no idea what this third argument it's asking for. I literally just copy pasted the get_by_natural_key from Django's own User manager, and put it into my own custom model.

Here's my user model:

class CustomUserManager(models.Manager):
    def get_absolute_url(self):
        return "/u/%s/" % urlquote(self.username)

    def get_username(self):
        'Returns the username'
        return self.username

    def get_full_name(self):
        """
        #Returns the first_name plus the last_name, with a space in between.
        """
        full_name = '%s %s' % (self.first_name, self.last_name)
        return full_name.strip()

    def get_short_name(self):
        "    Returns the short name for the user."
        return self.first_name

    def _create_user(self, username, email, password, **extra_fields):
        """
        Creates and saves a User with the given username, email and     password.
    """
        if not username:
            raise ValueError('The given username must be set')
        email = self.normalize_email(email)
        user = self.model(username=username, email=email, **extra_fields)
        user.set_password(password)
        user.save(using=self._db)
        return user

    def create_user(self, username, email=None, password=None, **extra_fields):
        extra_fields.setdefault('is_staff', False)
        extra_fields.setdefault('is_superuser', False)
        return self._create_user(username, email, password, **extra_fields)

    def create_superuser(self, username, email, password, **extra_fields):
        extra_fields.setdefault('is_staff', True)
        extra_fields.setdefault('is_superuser', True)

        if extra_fields.get('is_staff') is not True:
            raise ValueError('Superuser must have is_staff=True.')
        if extra_fields.get('is_superuser') is not True:
            raise ValueError('Superuser must have is_superuser=True.')

        return self._create_user(username, email, password, **extra_fields)

    @classmethod
    def normalize_email(cls, email):
        """
        Normalize the address by lowercasing the domain part of the email
        address.
        """
        email = email or ''
        try:
            email_name, domain_part = email.strip().rsplit('@', 1)
        except ValueError:
            pass
        else:
            email = '@'.join([email_name, domain_part.lower()])
        return email

    def get_by_natural_key(self, username, password):
        return self.get(username=username, password=password)


class CustomUser(AbstractBaseUser, PermissionsMixin):
    email = models.EmailField('email address', unique=True, db_index=True)
    username = models.CharField('username', max_length=50, unique=True,   db_index=True)
    first_name = models.CharField(max_length=50, blank=False)
    last_name = models.CharField(max_length=50, blank=False)
    joined = models.DateTimeField(auto_now_add=True)
    is_active = models.BooleanField(default=True)
    is_admin = models.BooleanField(default=False)
    date_joined = models.DateTimeField(_('date joined'), default=timezone.now)

    USERNAME_FIELD = 'username'
    REQUIRED_FIELDS = []

    objects = CustomUserManager()

    def __unicode__(self):
        return self.username

    class Meta:
        unique_together = (('username', 'password'),)

views.py

def register_user(request):
    if request.method == 'POST':
        form = RegistrationForm(request.POST)     # create form object
        if form.is_valid():
            form.save()
            return HttpResponseRedirect('/all')
    args = {}
    args.update(csrf(request))
    args['form'] = RegistrationForm()
    print args
    return render(request, 'register.html', args)


def login(request):
    """
    User Log in View
    """
    if request.method == 'POST':
        form = AuthenticationForm(data=request.POST)
        if form.is_valid():
            CustomUser = authenticate(username=request.POST['username'], password=request.POST['password'])
            if CustomUser is not None:
                if CustomUser.is_active:
                    django_login(request, CustomUser)
                    return redirect('all_posts.html')
    else:
        form = AuthenticationForm()
    return render_to_response('login.html', {
    'authenticationform': form,
    }, context_instance=RequestContext(request))

Answer 1

Django's own get_by_natural_key method takes only a username argument - your method is expecting a username as well as a password (not sure where you copied it from). From the documentation :

get_by_natural_key(username)

Retrieves a user instance using the contents of the field nominated by USERNAME_FIELD.

Drop your password argument and it should work (it doesn't really make any sense to fetch by password anyway):

def get_by_natural_key(self, username):
    return self.get(username=username)

Better still, why don't you just subclass BaseUserManager instead of reimplementing its logic? You are currently subclassing models.Manager .