我有2个模特

class Chassis(models.Model):
    number = models.CharField(max_length=10, unique=True)

class Eir(models.Model):
    chassis = models.ForeignKey(
        'management.Chassis',
        null=True,
        blank=True,
        related_name='eir',
        on_delete=models.SET_NULL
    )
    number = models.IntegerField(unique=True, default=0)

我通过Django CLI测试

>>> chassis = Chassis.objects.prefetch_related('eir')
>>> chassis
>>> chassis.first().eir.all()

我尝试了上面的命令，它仍然使用eir表进行查询，如下所示：

# produced from ">>> chassis"
{"Time":[2023-03-07 08:25:42 UTC], Host:10.116.1.165} LOG:  duration: 0.238 ms  statement: SELECT "management_chassis"."id", "management_chassis"."number" FROM "management_chassis" LIMIT 21
{"Time":[2023-03-07 08:25:42 UTC], Host:10.116.1.165} LOG:  duration: 0.777 ms  statement: SELECT "rental_eir"."id", "rental_eir"."number", "rental_eir"."chassis_id" FROM "rental_eir" WHERE "rental_eir"."chassis_id" IN (1292, 104)

# produced from ">>> chassis.first().eir.all()"
{"Time":[2023-03-07 08:25:59 UTC], Host:10.116.1.165} LOG:  duration: 0.239 ms  statement: SELECT "rental_eir"."id", "rental_eir"."number", "rental_eir"."chassis_id" FROM "rental_eir" WHERE "rental_eir"."chassis_id" IN (1292)

我希望不再有第三次查询，因为数据将被存储在内存中。我的真实的目的是与Django REST框架有关，在def to_representation中操作返回的数据，其中反向查找类似于ret['eir'] = instance.eir.all().last().id，其中instance是Chassis模型。
一般来说，我试图减少不必要的查询产生。