在 django rest 框架中创建多种类型的用户，得到一个意外的关键字参数“last_login”

Question

I am trying to learn Django, and I am creating various cases just to exercise and hopefully learn something new. Suppose that I am trying to create different users and assign different permissions latter, but first lets try to create them first. I was researching last night and it is a common problem and many differnt implementations. Most common that I have seen is with student, teacher, admin. My case is similar, but instead of teacher it is Staff as staff member. Staff inherits from User, which itself inherits from AbstractBaseUser. Below is my code for each class, model and serializer. User mode:

class User(AbstractBaseUser):
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)
    email = models.EmailField(db_index=True, unique=True)
    username = models.CharField(max_length=40, unique=True)

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ['first_name', 'last_name','username']

    objects = UserManager()

## And user manager:
class UserManager(BaseUserManager):

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

Model:

class Staff(User):
    qualification = models.CharField(db_index=True, max_length=255)
    department = models.CharField(db_index=True, max_length=10)

    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ['first_name', 'last_name', 'department','username']

    objects = StaffManager()

    def __str__(self):
        return self.first_name

Staff Model Manager:

class StaffManager(BaseUserManager):

    def create_staff(self, first_name, last_name, email, qualification, department, password=None):
        if email is None:
            raise TypeError('Users must have an email address.')
        staff = Staff(first_name=first_name, last_name=last_name,
                      email=self.normalize_email(email),
                      qualification=qualification, department=department)
        staff.set_password(password)
        staff.save()
        return staff

And the Staff Registartion Serializer:

class StaffRegistrationSerializer(serializers.ModelSerializer):
    password = serializers.CharField(
        max_length=128,
        min_length=8,
        write_only=True
    )
    token = serializers.CharField(max_length=255, read_only=True)
 
    class Meta:
        model = Staff
        fields = '__all__'
 
    def create(self, validated_data):
        return Staff.objects.create_staff(**validated_data)

The problem is that from the API, a field of Last login is created that it is not declared in models. And when I submit my form, I get this error:

TypeError: create_staff() got an unexpected keyword argument 'last_login'
[17/Dec/2020 15:44:43] "POST /api/auth/register-staff HTTP/1.1" 500 104579

I was looking at this which has the similar problem, but he has a different implementation and at this point, I do not fully understand so I could modify my code to act in the same way.

PS, I am folloing this tutorial to create multiple types of users.

Answer 1

The problem is that **validated_data has last_login with a value. So when you're passing in the kwargs of validated_data , it gets expanded into the function arguments for create_staff() but there's no slot for last_login .

The fix is to add , last_login=None to the definition of create_staff , and pass it along to the new Staff object. Eg:

def create_staff(self, first_name, last_name, email, qualification, department, password=None, last_login=None):
    # code cut for brevity
    staff = Staff(first_name=first_name, last_name=last_name,
                  email=self.normalize_email(email),
                  qualification=qualification, department=department,
                  last_login=last_login)