      name = models.CharField(max_length=100)
  
  
  class Widget(models.Model):
      owner = models.ForeignKey(Collector)
      name = models.CharField(max_length=100)
  
  
  class DooHickey(models.Model):
      code = models.CharField(max_length=10, primary_key=True)
 
</s> remove     owner = models.ForeignKey(Collector)
 </s> add     owner = models.ForeignKey(Collector, models.CASCADE) </s> remove     owner = models.ForeignKey(Collector)
 </s> add     owner = models.ForeignKey(Collector, models.CASCADE) </s> remove     owner = models.ForeignKey(Collector)
 </s> add     owner = models.ForeignKey(Collector, models.CASCADE) </s> remove     owner = models.ForeignKey(Collector)
 </s> add     owner = models.ForeignKey(Collector, models.CASCADE) </s> remove     owner = models.ForeignKey(User, null=True, blank=True, on_delete=models.SET_NULL)
 </s> add     owner = models.ForeignKey(User, models.SET_NULL, null=True, blank=True)
    owner = models.ForeignKey(Collector, models.CASCADE)
      name = models.CharField(max_length=100)
  
  
  class Widget(models.Model):
    owner = models.ForeignKey(Collector, models.CASCADE)
      name = models.CharField(max_length=100)
  
  
  class DooHickey(models.Model):
      code = models.CharField(max_length=10, primary_key=True)
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