          ordering = ['x']
  
  
  class LoopZ(models.Model):
      z = models.ForeignKey('self')
  
      class Meta:
          ordering = ['z']
  
  
 
</s> remove     x = models.ForeignKey(LoopX)
 </s> add     x = models.ForeignKey(LoopX, models.CASCADE) </s> remove     b = models.ForeignKey(B)
 </s> add     b = models.ForeignKey(B, models.CASCADE) </s> remove     b = models.ForeignKey(B, null=True)
 </s> add     b = models.ForeignKey(B, models.SET_NULL, null=True) </s> remove             parent = models.ForeignKey(Parent)
 </s> add             parent = models.ForeignKey(Parent, models.CASCADE) </s> remove     collector = models.ForeignKey(Collector)
 </s> add     collector = models.ForeignKey(Collector, models.CASCADE)
    z = models.ForeignKey('self', models.CASCADE)
          ordering = ['x']
  
  
  class LoopZ(models.Model):
    z = models.ForeignKey('self', models.CASCADE)
  
      class Meta:
          ordering = ['z']
  
  
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/queries/models.py