          class Band(models.Model):
              name = models.CharField(max_length=50)
  
          class BandMember(models.Model):
              band = UnsavedForeignKey(Band)
              first_name = models.CharField(max_length=50)
              last_name = models.CharField(max_length=50)
  
          beatles = Band(name='The Beatles')
          john = BandMember(first_name='John', last_name='Lennon')
 
</s> remove             band_ct = models.ForeignKey(ContentType)
 </s> add             band_ct = models.ForeignKey(ContentType, models.CASCADE) </s> remove         artist = models.ForeignKey(Musician)
 </s> add         artist = models.ForeignKey(Musician, on_delete=models.CASCADE) </s> remove     related = models.ForeignKey(Secondary)
 </s> add     related = models.ForeignKey(Secondary, models.CASCADE) </s> remove     restaurant = models.ForeignKey(Restaurant)
 </s> add     restaurant = models.ForeignKey(Restaurant, models.CASCADE) </s> remove     work_at = models.ForeignKey(Restaurant)
 </s> add     work_at = models.ForeignKey(Restaurant, models.CASCADE)
            band = UnsavedForeignKey(Band, models.CASCADE)
          class Band(models.Model):
              name = models.CharField(max_length=50)
  
          class BandMember(models.Model):
            band = UnsavedForeignKey(Band, models.CASCADE)
              first_name = models.CharField(max_length=50)
              last_name = models.CharField(max_length=50)
  
          beatles = Band(name='The Beatles')
          john = BandMember(first_name='John', last_name='Lennon')
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/many_to_one/tests.py