text: from django.contrib.auth.base_user import BaseUserManager
  from django.db import models
  from django.contrib.auth.models import AbstractUser
  from django.db.models.signals import post_save
  from django.dispatch import receiver
  from django.utils.translation import ugettext_lazy as _
  
  
  class UserManager(BaseUserManager):
      """Define a model manager for User model with no username field."""
  
      use_in_migrations = True
  
      def _create_user(self, email, password, **extra_fields):
          """Create and save a User with the given email and password."""
          if not email:
              raise ValueError('The given email must be set')
          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, password=None, **extra_fields):
          """Create and save a regular User with the given email and password."""
          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, password, **extra_fields):
          """Create and save a SuperUser with the given email and password."""
          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(AbstractUser):
      username = None
      email = models.EmailField(_('email address'), unique=True)
      USER_TYPE_CHOICES = (
          (1, 'student'),
          (2, 'teacher'),
          (3, 'secretary'),
          (4, 'supervisor'),
          (5, 'admin'),
      )
      user_type = models.PositiveSmallIntegerField(choices=USER_TYPE_CHOICES)
  
      USERNAME_FIELD = 'email'
      REQUIRED_FIELDS = ['user_type']
  
      class Meta:
          verbose_name = 'User'
          verbose_name_plural = 'Users'
          ordering = ('id',)
  
      def __unicode__(self):
          return u'{0} ({1})'.format(self.get_full_name(), self.email)
  
      def get_full_name(self):
          return u'{0} {1}'.format(self.first_name, self.last_name)
  
      def get_short_name(self):
          return self.email
  
      def get_username(self):
          return self.email
  
      objects = UserManager()
  
  
  class Profile(models.Model):
      user = models.OneToOneField(User, on_delete=models.CASCADE, primary_key=True)
      father_name = models.CharField(max_length=100, null=True, blank=True)
      mother_name = models.CharField(max_length=100, null=True, blank=True)
      bio = models.TextField(max_length=500, blank=True)
      location = models.CharField(max_length=100, blank=True)
      birth_date = models.DateField(null=True, blank=True)
  
  
  @receiver(post_save, sender=User)
  def update_user_profile(sender, instance, created, **kwargs):
      if created:
          Profile.objects.create(user=instance)
      # instance.profile.save()
  
  
  @receiver(post_save, sender=User)
  def save_user_profile(sender, instance, **kwargs):
      instance.profile.save()
  