old_contents: from django.db import models
  
  
  class Promotion(models.Model):
  
      name = models.CharField(max_length=255)
      start_date = models.DateField()
      end_date = models.DateField(null=True, blank=True)
  
      parent = models.ForeignKey("self", null=True, blank=True)
  
  
  class Title(models.Model):
  
      name = models.CharField(max_length=127)
      active_start_date = models.DateField()
      active_end_date = models.DateField(null=True, blank=True)
  
new_contents: from django.db import models
  
  
  class Promotion(models.Model):
  
      name = models.CharField(max_length=255)
      start_date = models.DateField()
      end_date = models.DateField(null=True, blank=True)
  
      parent = models.ForeignKey("self", null=True, blank=True)
  
      def __unicode__(self):
          return self.name
  
  
  class Title(models.Model):
  
      name = models.CharField(max_length=127)
      active_start_date = models.DateField()
      active_end_date = models.DateField(null=True, blank=True)
  
      def __unicode__(self):
          return self.name
  
subject: Add unicode methods.