  class FootNote(models.Model):
      """
      Model added for ticket 19838
      """
      chapter = models.ForeignKey(Chapter, on_delete=models.PROTECT)
      note = models.CharField(max_length=40)
  
  # Models for #16838
  
  
 
</s> remove     novel = models.ForeignKey(Novel)
 </s> add     novel = models.ForeignKey(Novel, models.CASCADE) </s> remove     holder = models.ForeignKey(Holder3)
 </s> add     holder = models.ForeignKey(Holder3, models.CASCADE) </s> remove     parent = models.ForeignKey('self', null=True, blank=True)
 </s> add     parent = models.ForeignKey('self', models.SET_NULL, null=True, blank=True) </s> remove     capo_famiglia = models.ForeignKey(CapoFamiglia)
 </s> add     capo_famiglia = models.ForeignKey(CapoFamiglia, models.CASCADE) </s> remove     parent = models.ForeignKey(ParentWithDependentChildren)
 </s> add     parent = models.ForeignKey(ParentWithDependentChildren, models.CASCADE)
    chapter = models.ForeignKey(Chapter, models.PROTECT)
  class FootNote(models.Model):
      """
      Model added for ticket 19838
      """
    chapter = models.ForeignKey(Chapter, models.PROTECT)
      note = models.CharField(max_length=40)
  
  # Models for #16838
  
  
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