old_contents: from django.db import models
  
  
  class Picture(models.Model):
      """
      This is a small demo using just two fields. ImageField depends on PIL or
      pillow (where Pillow is easily installable in a virtualenv. If you have
      problems installing pillow, use a more generic FileField instead.
      """
  
      picture_file = models.ImageField(upload_to="pictures")
  
      def __unicode__(self):
          return self.picture_file.name
  
new_contents: from django.db import models
  
  
  class Picture(models.Model):
      """
      This is a small demo using just two fields. ImageField depends on PIL or
      pillow (where Pillow is easily installable in a virtualenv. If you have
      problems installing pillow, use a more generic FileField instead.
      """
  
      file = models.ImageField(upload_to="pictures")
  
      def __unicode__(self):
          return self.file.name
  
subject: Use the same name for the field in frontend and backend