  
  
  class Concert(models.Model):
      name = models.CharField(max_length=30)
      group = models.ForeignKey(Group)
  
  
  class Membership(models.Model):
      music = models.ForeignKey(Musician)
      group = models.ForeignKey(Group)
 
</s> remove     music = models.ForeignKey(Musician)
    group = models.ForeignKey(Group)
 </s> add     music = models.ForeignKey(Musician, models.CASCADE)
    group = models.ForeignKey(Group, models.CASCADE) </s> remove             person = models.ForeignKey(Person)
            group = models.ForeignKey(Group)
 </s> add             person = models.ForeignKey(Person, models.CASCADE)
            group = models.ForeignKey(Group, models.CASCADE) </s> remove     username = models.ForeignKey(Email, related_name='primary')
    email = models.ForeignKey(Email, to_field='email', related_name='secondary')
    group = models.ForeignKey(Group)
 </s> add     username = models.ForeignKey(Email, models.CASCADE, related_name='primary')
    email = models.ForeignKey(Email, models.CASCADE, to_field='email', related_name='secondary')
    group = models.ForeignKey(Group, models.CASCADE) </s> remove         person = models.ForeignKey(Person)
        group = models.ForeignKey(Group)
 </s> add         person = models.ForeignKey(Person, on_delete=models.CASCADE)
        group = models.ForeignKey(Group, on_delete=models.CASCADE) </s> remove     location = models.ForeignKey(AugmentedLocation)
 </s> add     location = models.ForeignKey(AugmentedLocation, models.CASCADE)
    group = models.ForeignKey(Group, models.CASCADE)
  
  
  class Concert(models.Model):
      name = models.CharField(max_length=30)
    group = models.ForeignKey(Group, models.CASCADE)
  
  
  class Membership(models.Model):
      music = models.ForeignKey(Musician)
      group = models.ForeignKey(Group)
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/admin_changelist/models.py