old_contents: from django.contrib.auth.models import AbstractBaseUser, UserManager
  from django.db import models
  from django.utils import timezone
  
  
  class User(AbstractBaseUser):
      username = models.CharField('username', max_length=128, unique=True)
      first_name = models.CharField('first name', max_length=30, blank=True)
      last_name = models.CharField('last name', max_length=30, blank=True)
      email = models.EmailField('email address', blank=True)
      is_active = models.BooleanField('active', default=True)
      is_superuser = models.BooleanField('superuser status', default=False)
      date_joined = models.DateTimeField('date joined', default=timezone.now)
  
      objects = UserManager()
  
      USERNAME_FIELD = 'username'
      REQUIRED_FIELDS = ['email']
  
      class Meta:
          app_label = 'simpleoncall'
          db_table = 'auth_user'
          verbose_name = 'user'
          verbose_name_plural = 'users'
  
      def save(self, *args, **kwargs):
          if not self.username:
              self.username = self.email
          return super(User, self).save(*args, **kwargs)
  
new_contents: from django.contrib.auth.models import AbstractBaseUser, UserManager
  from django.db import models
  from django.utils import timezone
  
  
  class User(AbstractBaseUser):
      username = models.CharField('username', max_length=128, unique=True)
      first_name = models.CharField('first name', max_length=30, blank=True)
      last_name = models.CharField('last name', max_length=30, blank=True)
      email = models.EmailField('email address', blank=True)
      is_active = models.BooleanField('active', default=True)
      is_superuser = models.BooleanField('superuser status', default=False)
      date_joined = models.DateTimeField('date joined', default=timezone.now)
  
      objects = UserManager()
  
      USERNAME_FIELD = 'username'
      REQUIRED_FIELDS = ['email']
  
      class Meta:
          app_label = 'simpleoncall'
          db_table = 'auth_user'
          verbose_name = 'user'
          verbose_name_plural = 'users'
  
      def save(self, *args, **kwargs):
          if not self.username:
              self.username = self.email
          return super(User, self).save(*args, **kwargs)
  
      def get_full_name(self):
          return '%s %s' % (self.first_name, self.last_name)
  
subject: add get_full_name to User model