AbstractBaseUser is Flexible and Not So Complicated

fields=[
    ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
    ('password', models.CharField(max_length=128, verbose_name='password')),
    ('last_login', models.DateTimeField(blank=True, null=True, verbose_name='last login')),
    ('is_superuser', models.BooleanField(default=False, help_text='Designates that this user has all permissions without explicitly assigning them.', verbose_name='superuser status')),
    ('username', models.CharField(error_messages={'unique': 'A user with that username already exists.'}, help_text='Required. 150 characters or fewer. Letters, digits and @/./+/-/_ only.', max_length=150, unique=True, validators=[django.contrib.auth.validators.UnicodeUsernameValidator()], verbose_name='username')),
    ('first_name', models.CharField(blank=True, max_length=150, verbose_name='first name')),
    ('last_name', models.CharField(blank=True, max_length=150, verbose_name='last name')),
    ('email', models.EmailField(blank=True, max_length=254, verbose_name='email address')),
    ('is_staff', models.BooleanField(default=False, help_text='Designates whether the user can log into this admin site.', verbose_name='staff status')),
    ('is_active', models.BooleanField(default=True, help_text='Designates whether this user should be treated as active. Unselect this instead of deleting accounts.', verbose_name='active')),
    ('date_joined', models.DateTimeField(default=django.utils.timezone.now, verbose_name='date joined')),
    ('groups', models.ManyToManyField(blank=True, help_text='The groups this user belongs to. A user will get all permissions granted to each of their groups.', related_name='user_set', related_query_name='user', to='auth.Group', verbose_name='groups')),
    ('user_permissions', models.ManyToManyField(blank=True, help_text='Specific permissions for this user.', related_name='user_set', related_query_name='user', to='auth.Permission', verbose_name='user permissions')),
],

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

# For validating by username
from django.core.validators import MinLengthValidator, RegexValidator

class MyUser(AbstractBaseUser, PermissionsMixin):

    username = models.CharField(verbose_name='username', max_length=10, unique=True, validators=[MinLengthValidator(5,), RegexValidator(r'^[a-zA-Z0-9]*$',)])
    first_name = models.CharField(blank=True, max_length=50, verbose_name='first name')
    last_name = models.CharField(blank=True, max_length=50, verbose_name='last name')
    email = models.EmailField(verbose_name='Email', max_length=50, unique=True)
    date_of_birth = models.DateField(verbose_name="Birthday", blank=True, null=True)
    introduction = models.TextField(verbose_name='Introduction', max_length=300, blank=True, null=True)
    date_joined = models.DateTimeField(verbose_name='Registered', auto_now_add=True)

    # Active by default during registration, without staff or admin permissions
    is_active = models.BooleanField(default=True)
    is_staff = models.BooleanField(default=False)
    is_admin = models.BooleanField(default=False)

    # AbstractBaseUser requires MyUserManager
    objects = MyUserManager()
    # Used as a unique identifier
    USERNAME_FIELD = 'email'
    # List of field names to be prompted when creating a user。
    REQUIRED_FIELDS = ['username']

    def __str__(self):
        return self.username

class MyUserManager(BaseUserManager):
    def create_user(self, username, email, password=None):
        if not username:
            raise ValueError('Users must have an username')
        if not email:
            raise ValueError('Users must have an email address')

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

    def create_superuser(self, username, email, password):
        user = self.create_user(
            username=username,
            email=self.normalize_email(email),
            password=password,
        )
        user.is_admin=True
        user.is_staff=True
        user.is_superuser=True
        user.save(using=self._db)
        return user

from django.contrib import admin

# Register your models here.
from student.models import MyUser


# Show items you want on the admin-site
@admin.register(MyUser)
class MyUserAdmin(admin.ModelAdmin):
    list_display = ('id', 'username', 'first_name', 'last_name', 'email', 'date_of_birth')