  
  
  class ParentWithFK(models.Model):
      fk = models.ForeignKey(
          ReferencedByParent, to_field='name', related_name='hidden+',
      )
  
  
  class ChildOfReferer(ParentWithFK):
      pass
 
</s> remove         ReferencedByInline, to_field='name', related_name='hidden+',
 </s> add         ReferencedByInline,
        models.CASCADE,
        to_field='name',
        related_name='hidden+', </s> remove             fk = models.ForeignKey(VeryLongModelNamezzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz, related_name="rn4")
 </s> add             fk = models.ForeignKey(
                VeryLongModelNamezzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,
                models.CASCADE,
                related_name="rn4",
            ) </s> remove             fk = models.ForeignKey(Target)
 </s> add             fk = models.ForeignKey(Target, models.CASCADE) </s> remove     author = models.ForeignKey(Author, to_field='name', related_name='i_like')
    likes_author = models.ForeignKey(Author, to_field='name', related_name='likes_me')
 </s> add     author = models.ForeignKey(Author, models.CASCADE, to_field='name', related_name='i_like')
    likes_author = models.ForeignKey(Author, models.CASCADE, to_field='name', related_name='likes_me') </s> remove     author = models.ForeignKey(Author, to_field='name', related_name='addresses')
 </s> add     author = models.ForeignKey(Author, models.CASCADE, to_field='name', related_name='addresses')
        ReferencedByParent,
        models.CASCADE,
        to_field='name',
        related_name='hidden+',
  
  
  class ParentWithFK(models.Model):
      fk = models.ForeignKey(
        ReferencedByParent,
        models.CASCADE,
        to_field='name',
        related_name='hidden+',
      )
  
  
  class ChildOfReferer(ParentWithFK):
      pass
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