old_contents: from django.db import models
  from django.contrib.auth.models import User
  
  
  class Country(models.Model):
      name = models.CharField(max_length=50)
      country_code = models.CharField(max_length=5)
  
      def __str__(self):
          return self.name
  
  
  class Status(models.Model):
      name = models.CharField(max_length=10)
  
      def __str__(self):
          return self.name
  
  
  class Author(models.Model):
      first_name = models.CharField(max_length=50)
      middle_name = models.CharField(max_length=20, blank=True)
      last_name = models.CharField(max_length=100)
      date_of_birth = models.DateField('Date of birth')
      birthplace = models.CharField(max_length=100)
      country = models.ForeignKey(Country)
  
      def __str__(self):
          return '{0} {1} {2}'.format(self.first_name,
                                      self.middle_name, self.last_name)
  
  
  class Book(models.Model):
      author = models.ForeignKey(Author)
      title = models.CharField(max_length=200)
      pub_date = models.DateField('Publication date')
  
      def __str__(self):
          return self.title
  
  
  class BookStatus(models.Model):
      status = models.ForeignKey(Status)
      book = models.ForeignKey(Book)
  
  
  class BookReader(models.Model):
      user = models.OneToOneField(User)
      books_status = models.ManyToManyField(BookStatus)
      friends = models.ManyToManyField('self')
  
  
  class Review(models.Model):
      review_text = models.TextField()
      rating = models.IntegerField()
      reviewer = models.ForeignKey(BookReader)
  
new_contents: from django.db import models
  from django.contrib.auth.models import User
  
  
  class Country(models.Model):
      name = models.CharField(max_length=50)
      country_code = models.CharField(max_length=5)
  
      def __str__(self):
          return self.name
  
  
  class Status(models.Model):
      name = models.CharField(max_length=10)
  
      def __str__(self):
          return self.name
  
  
  class Author(models.Model):
      first_name = models.CharField(max_length=50)
      middle_name = models.CharField(max_length=20, blank=True)
      last_name = models.CharField(max_length=100)
      date_of_birth = models.DateField('Date of birth')
      birthplace = models.CharField(max_length=100)
      country = models.ForeignKey(Country)
  
      def __str__(self):
          return '{0} {1} {2}'.format(self.first_name,
                                      self.middle_name, self.last_name)
  
  
  class Book(models.Model):
      author = models.ForeignKey(Author)
      title = models.CharField(max_length=200)
      pub_date = models.DateField('Publication date')
  
      def __str__(self):
          return self.title
  
  
  class BookStatus(models.Model):
      status = models.ForeignKey(Status)
      book = models.ForeignKey(Book)
      book_reader = models.ForeignKey('BookReader')
  
  
  class BookReader(models.Model):
      user = models.OneToOneField(User)
      friends = models.ManyToManyField('self')
  
  
  class Review(models.Model):
      review_text = models.TextField()
      rating = models.IntegerField()
      reviewer = models.ForeignKey(BookReader)
  
subject: change bookreader