      # model helps to test that.
      first_name = models.CharField(max_length=20)
      manager = models.BooleanField(default=False)
      last_name = models.CharField(max_length=20)
      store = models.ForeignKey(Store)
      age = models.IntegerField()
      salary = models.DecimalField(max_digits=8, decimal_places=2)
  
      def __str__(self):
          return '%s %s' % (self.first_name, self.last_name)
 
</s> remove     leader = models.ForeignKey(Actor)
 </s> add     leader = models.ForeignKey(Actor, models.CASCADE) </s> remove     company = models.ForeignKey(Company, help_text="place of work")
    family = models.ForeignKey(Family, related_name='+', null=True)
 </s> add     company = models.ForeignKey(Company, models.CASCADE, help_text="place of work")
    family = models.ForeignKey(Family, models.SET_NULL, related_name='+', null=True) </s> remove     content_type = models.ForeignKey(ContentType)
 </s> add     content_type = models.ForeignKey(ContentType, models.CASCADE) </s> remove     question = models.ForeignKey(Question, on_delete=models.PROTECT)
 </s> add     question = models.ForeignKey(Question, models.PROTECT) </s> remove     color = models.ForeignKey(Color, limit_choices_to={'warm': True})
 </s> add     color = models.ForeignKey(Color, models.CASCADE, limit_choices_to={'warm': True})
    store = models.ForeignKey(Store, models.CASCADE)
      # model helps to test that.
      first_name = models.CharField(max_length=20)
      manager = models.BooleanField(default=False)
      last_name = models.CharField(max_length=20)
    store = models.ForeignKey(Store, models.CASCADE)
      age = models.IntegerField()
      salary = models.DecimalField(max_digits=8, decimal_places=2)
  
      def __str__(self):
          return '%s %s' % (self.first_name, self.last_name)
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/annotations/models.py