      slug = models.SlugField()
  
  
  class PrePopulatedSubPost(models.Model):
      post = models.ForeignKey(PrePopulatedPost)
      subtitle = models.CharField(max_length=100)
      subslug = models.SlugField()
  
  
  class Post(models.Model):
 
</s> remove     author = models.ForeignKey(Author)
 </s> add     author = models.ForeignKey(Author, models.CASCADE) </s> remove     post = models.ForeignKey("Post")
 </s> add     post = models.ForeignKey("Post", models.CASCADE) </s> remove     post = models.ForeignKey(Post, related_name='attached_%(class)s_set')
 </s> add     post = models.ForeignKey(Post, models.CASCADE, related_name='attached_%(class)s_set') </s> remove     content_type = models.ForeignKey(ContentType, related_name='tagged_items')
 </s> add     content_type = models.ForeignKey(ContentType, models.CASCADE, related_name='tagged_items') </s> remove     content_type = models.ForeignKey(ContentType, related_name="taggeditem_set2")
 </s> add     content_type = models.ForeignKey(
        ContentType,
        models.CASCADE,
        related_name="taggeditem_set2",
    )
    post = models.ForeignKey(PrePopulatedPost, models.CASCADE)
      slug = models.SlugField()
  
  
  class PrePopulatedSubPost(models.Model):
    post = models.ForeignKey(PrePopulatedPost, models.CASCADE)
      subtitle = models.CharField(max_length=100)
      subslug = models.SlugField()
  
  
  class Post(models.Model):
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/admin_views/models.py