          # ...
          pass
  
      class Car(models.Model):
          manufacturer = models.ForeignKey(Manufacturer)
          # ...
  
  You can also create :ref:`recursive relationships <recursive-relationships>` (an
  object with a many-to-one relationship to itself) and :ref:`relationships to
  models not yet defined <lazy-relationships>`; see :ref:`the model field
 
</s> remove         company_that_makes_it = models.ForeignKey(Manufacturer)
 </s> add         company_that_makes_it = models.ForeignKey(
            Manufacturer,
            on_delete=models.CASCADE,
        ) </s> remove     honeycomb = models.ForeignKey(Honeycomb)
 </s> add     honeycomb = models.ForeignKey(Honeycomb, models.CASCADE) </s> remove         zip_code = models.ForeignKey(ZipCode)
 </s> add         zip_code = models.ForeignKey(
            ZipCode,
            on_delete=models.SET_NULL,
            blank=True,
            null=True,
        ) </s> remove model was altered to ``blog = ForeignKey(Blog, related_name='entries')``, the
above example code would look like this::
 </s> add model was altered to ``blog = ForeignKey(Blog, on_delete=models.CASCADE,
related_name='entries')``, the above example code would look like this:: </s> remove         author = models.ForeignKey(Author)
 </s> add         author = models.ForeignKey(Author, on_delete=models.CASCADE)
        manufacturer = models.ForeignKey(Manufacturer, on_delete=models.CASCADE)
          # ...
          pass
  
      class Car(models.Model):
        manufacturer = models.ForeignKey(Manufacturer, on_delete=models.CASCADE)
          # ...
  
  You can also create :ref:`recursive relationships <recursive-relationships>` (an
  object with a many-to-one relationship to itself) and :ref:`relationships to
  models not yet defined <lazy-relationships>`; see :ref:`the model field
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
docs/topics/db/models.txt