old_contents: from django.db import models
  
  # Create your models here.
  
  
  class Box(models.Model):
      disk_no = models.IntegerField()
      created_at = models.DateTimeField(auto_now_add=True)
  
      def __str__(self):
          return str(self.disk_no)
  
  
  class Disk(models.Model):
      box_no = models.ForeignKey(Box)
      serial = models.IntegerField()
      titles = models.TextField()
  
      def __str__(self):
          return '%s %s' % (self.serial, self.titles)
new_contents: from django.db import models
  
  # Create your models here.
  
  
  class Box(models.Model):
      disk_no = models.IntegerField()
      created_at = models.DateTimeField(auto_now_add=True)
  
      def __str__(self):
          #return str(self.disk_no)
          return "%s %s" % (self.disk_no, self.created_at)
  
  
  class Disk(models.Model):
      box_no = models.ForeignKey(Box)
      serial = models.IntegerField()
      titles = models.TextField()
  
      def __str__(self):
          return '%s %s' % (self.serial, self.titles)
subject: update to template friendly ! :O