Custom user manager in Django to get rid of username field.

custom_user_manager_no_username.py

from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager
from django.contrib.auth.models import PermissionsMixin
from django.db import models
from django.utils import timezone

class UserManager(BaseUserManager):
    """Custom user manager"""
    use_in_migrations = True

    def _create_user(self, email, password, **extra_fields):

        if not email:
            raise ValueError("Users must have an email address")

        email = self.normalize_email(email)
        user = self.model(email=email, **extra_fields)
        user.set_password(password)
        user.save(using=self._db)
        return user

    def create_user(self, email=None, password=None, **extra_fields):
        """Create normal user"""
        extra_fields.setdefault("is_staff", False)
        extra_fields.setdefault("is_superuser", False)
        return self._create_user(email, password, **extra_fields)

    def create_superuser(self, email=None, password=None, **extra_fields):
        """Create superuser"""
        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(email, password, **extra_fields)


class User(PermissionsMixin, AbstractBaseUser):
    """Custom user model"""
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)
    email = models.EmailField(unique=True)

    is_staff = models.BooleanField(
        "staff status",
        default=False,
        help_text="Designates whether the user can log into this admin site.",
    )
    is_active = models.BooleanField(
        "active",
        default=True,
        help_text=
            "Designates whether this user should be treated as active. "
            "Unselect this instead of deleting accounts."
        ,
    )
    date_joined = models.DateTimeField("date joined", default=timezone.now)

    objects = UserManager()

    USERNAME_FIELD = "email"
    REQUIRED_FIELDS = ["first_name", "last_name"]

    @property
    def fullname(self) -> str:
        """Concatenate first_name and last_name"""
        return f"{self.first_name} {self.last_name}"

    def __str__(self) -> str:
        return f"{self.fullname}"