      recipes = models.ManyToManyField(Recipe, through='RecipeIngredient')
  
  
  class RecipeIngredient(models.Model):
      ingredient = models.ForeignKey(Ingredient, to_field='iname')
      recipe = models.ForeignKey(Recipe, to_field='rname')
  
  
  # Model for #23839
  class NotReferenced(models.Model):
      # Don't point any FK at this model.
 
</s> remove     swallow = models.OneToOneField(Swallow)
 </s> add     swallow = models.OneToOneField(Swallow, models.CASCADE) </s> remove     chapter = models.ForeignKey(Chapter, on_delete=models.PROTECT)
 </s> add     chapter = models.ForeignKey(Chapter, models.PROTECT) </s> remove     parent = models.OneToOneField(Place)
 </s> add     parent = models.OneToOneField(Place, models.CASCADE) </s> remove             content_type = models.ForeignKey('self')  # should point to ContentType
 </s> add             content_type = models.ForeignKey('self', models.CASCADE)  # should point to ContentType </s> remove     novel = models.ForeignKey(Novel)
 </s> add     novel = models.ForeignKey(Novel, models.CASCADE)
    ingredient = models.ForeignKey(Ingredient, models.CASCADE, to_field='iname')
    recipe = models.ForeignKey(Recipe, models.CASCADE, to_field='rname')
      recipes = models.ManyToManyField(Recipe, through='RecipeIngredient')
  
  
  class RecipeIngredient(models.Model):
    ingredient = models.ForeignKey(Ingredient, models.CASCADE, to_field='iname')
    recipe = models.ForeignKey(Recipe, models.CASCADE, to_field='rname')
    ingredient = models.ForeignKey(Ingredient, models.CASCADE, to_field='iname')
    recipe = models.ForeignKey(Recipe, models.CASCADE, to_field='rname')
  
  
  # Model for #23839
  class NotReferenced(models.Model):
      # Don't point any FK at this model.
keep keep keep keep replace replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/admin_views/models.py