          timestamps = DateTimeRangeField(blank=True, null=True)
          dates = DateRangeField(blank=True, null=True)
  
      class RangeLookupsModel(PostgreSQLModel):
          parent = models.ForeignKey(RangesModel, blank=True, null=True)
          integer = models.IntegerField(blank=True, null=True)
          big_integer = models.BigIntegerField(blank=True, null=True)
          float = models.FloatField(blank=True, null=True)
          timestamp = models.DateTimeField(blank=True, null=True)
          date = models.DateField(blank=True, null=True)
 
</s> remove     alfa = models.ForeignKey(Alfa, null=True)
    bravo = models.ForeignKey(Bravo, null=True)
 </s> add     alfa = models.ForeignKey(Alfa, models.SET_NULL, null=True)
    bravo = models.ForeignKey(Bravo, models.SET_NULL, null=True) </s> remove     collection = models.ForeignKey(ProfileCollection, blank=True, null=True)
 </s> add     collection = models.ForeignKey(ProfileCollection, models.SET_NULL, blank=True, null=True) </s> remove     owner = models.ForeignKey('Person', null=True)
    main_room = models.OneToOneField('Room', related_name='main_room_of', null=True)
 </s> add     owner = models.ForeignKey('Person', models.SET_NULL, null=True)
    main_room = models.OneToOneField('Room', models.SET_NULL, related_name='main_room_of', null=True) </s> remove     parent = models.ForeignKey('self', to_field='barcode', blank=True, null=True)
 </s> add     parent = models.ForeignKey('self', models.SET_NULL, to_field='barcode', blank=True, null=True) </s> remove     parent = models.ForeignKey('self', null=True)
 </s> add     parent = models.ForeignKey('self', models.CASCADE, null=True)
        parent = models.ForeignKey(RangesModel, models.SET_NULL, blank=True, null=True)
          timestamps = DateTimeRangeField(blank=True, null=True)
          dates = DateRangeField(blank=True, null=True)
  
      class RangeLookupsModel(PostgreSQLModel):
        parent = models.ForeignKey(RangesModel, models.SET_NULL, blank=True, null=True)
          integer = models.IntegerField(blank=True, null=True)
          big_integer = models.BigIntegerField(blank=True, null=True)
          float = models.FloatField(blank=True, null=True)
          timestamp = models.DateTimeField(blank=True, null=True)
          date = models.DateField(blank=True, null=True)
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/postgres_tests/models.py