text: """
  Specifying ordering
  
  Specify default ordering for a model using the ``ordering`` attribute, which
  should be a list or tuple of field names. This tells Django how to order
  ``QuerySet`` results.
  
  If a field name in ``ordering`` starts with a hyphen, that field will be
  ordered in descending order. Otherwise, it'll be ordered in ascending order.
  The special-case field name ``"?"`` specifies random order.
  
  The ordering attribute is not required. If you leave it off, ordering will be
  undefined -- not random, just undefined.
  """
  
  from django.db import models
  
  
  class Author(models.Model):
      name = models.CharField(max_length=63, null=True, blank=True)
  
      class Meta:
          ordering = ('-pk',)
  
  
  class Article(models.Model):
      author = models.ForeignKey(Author, models.SET_NULL, null=True)
      second_author = models.ForeignKey(Author, models.SET_NULL, null=True, related_name='+')
      headline = models.CharField(max_length=100)
      pub_date = models.DateTimeField()
  
      class Meta:
          ordering = (
              '-pub_date',
              models.F('headline'),
              models.F('author__name').asc(),
              models.OrderBy(models.F('second_author__name')),
          )
  
  
  class OrderedByAuthorArticle(Article):
      class Meta:
          proxy = True
          ordering = ('author', 'second_author')
  
  
  class OrderedByFArticle(Article):
      class Meta:
          proxy = True
          ordering = (models.F('author').asc(nulls_first=True), 'id')
  
  
  class ChildArticle(Article):
      pass
  
  
  class Reference(models.Model):
      article = models.ForeignKey(OrderedByAuthorArticle, models.CASCADE)
  
      class Meta:
          ordering = ('article',)
  