Extending AbstractUser to write a custom User model in Django.

admin.py

"""
Your admin must also inherit from Django default `UserAdmin`, if you want to save
your time from all the hassle of creating some methods they have already created.

Now you can edit user admin the way you want by also getting advantage of all the 
existing admin features.
"""

from django.contrib.auth import get_user_model
from django.contrib.auth.admin import UserAdmin as OrigUserAdmin

User = get_user_model()


@admin.register(User)
class UserAdmin(OrigUserAdmin):
  list_display = (
    'id', 'first_name', 'last_name', 'username', 'email', 'is_active'
  )

models.py

"""
Let's just say we have a ``users`` app in our system and inside the 
``models.py`` file we write our User model.
Also I've added another field for storing cellphone of number of the
user.

In this example, we are extending Django User model and making email
field as our main field for authentication. By default Django uses
``username`` field for authentication. In order to do this we have to
mark email field as unique and update ``USERNAME_FIELD`` value of the
AbstractUser class.

This scheme gives us flexibility to use all the exisiting features
of Django User model and override what we need, while making sure
we don't have to write much code.

In similar way, you can also extender or override Django BaseUserManager
from ``django.contrib.auth.base_user``
"""
from django.contrib.auth.models import AbstractUser
from django.db import models
from django.utils.translation import gettext_lazy as _


class User(AbstractUser):
	EMAIL_FIELD = 'email'
	USERNAME_FIELD = 'email'
	REQUIRED_FIELDS = ['username']
	
	email = models.EmailField(
		_('email address'),
		unique=True,
		blank=True
	)
	cellphone = models.CharField(
		_('cell phone'),
		max_length=20,
		null=True, blank=True
	)

settings.py

"""
In settings file, you have to specify path to the user model you've
just created. ``<app_name>.<ModelClassName>``
"""
AUTH_USER_MODEL = 'users.User'