  
  
  class SillyModel(models.Model):
      silly_field = models.BooleanField(default=False)
      silly_tribble = models.ForeignKey("migrations.Tribble")
      is_trouble = models.BooleanField(default=True)
 
</s> remove     owner = models.ForeignKey(Collector)
 </s> add     owner = models.ForeignKey(Collector, models.CASCADE) </s> remove     tag = models.ForeignKey(Tag)
 </s> add     tag = models.ForeignKey(Tag, models.CASCADE) </s> remove     chef = models.ForeignKey(Chef, null=True, blank=True)
 </s> add     chef = models.ForeignKey(Chef, models.SET_NULL, null=True, blank=True) </s> remove     post = models.ForeignKey("Post")
 </s> add     post = models.ForeignKey("Post", models.CASCADE) </s> remove     related = models.OneToOneField(RelatedModel)
 </s> add     related = models.OneToOneField(RelatedModel, models.CASCADE)
    silly_tribble = models.ForeignKey("migrations.Tribble", models.CASCADE)
  
  
  class SillyModel(models.Model):
      silly_field = models.BooleanField(default=False)
    silly_tribble = models.ForeignKey("migrations.Tribble", models.CASCADE)
      is_trouble = models.BooleanField(default=True)
keep keep keep keep replace keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/migrations/migrations_test_apps/unmigrated_app/models.py