  
  
  class EditablePKBook(models.Model):
      manual_pk = models.IntegerField(primary_key=True)
      author = models.ForeignKey(Author)
      title = models.CharField(max_length=50)
  
  
  class Holder(models.Model):
      dummy = models.IntegerField()
 
</s> remove     author = models.ForeignKey(Author)
 </s> add     author = models.ForeignKey(Author, models.CASCADE) </s> remove     holder = models.ForeignKey(Holder2)
 </s> add     holder = models.ForeignKey(Holder2, models.CASCADE) </s> remove     author = models.ForeignKey(Author)
 </s> add     author = models.ForeignKey(Author, models.CASCADE) </s> remove     author = models.ForeignKey(Author, unique=True)
 </s> add     author = models.ForeignKey(Author, models.CASCADE, unique=True) </s> remove     author = models.ForeignKey(Author)
 </s> add     author = models.ForeignKey(Author, models.CASCADE)
    author = models.ForeignKey(Author, models.CASCADE)
  
  
  class EditablePKBook(models.Model):
      manual_pk = models.IntegerField(primary_key=True)
    author = models.ForeignKey(Author, models.CASCADE)
      title = models.CharField(max_length=50)
  
  
  class Holder(models.Model):
      dummy = models.IntegerField()
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/admin_inlines/models.py