python - Django多表继承和 Graphite 烯

Question

我正在尝试通过 django-graphene 提供 graphql 端点。我有以下型号:

class BaseModel(models.Model):
    fk = models.ForeignKey(MainModel, related_name='bases')
    base_info = models.CharField(...)

class ChildModel(BaseModel):
    name = models.CharField(...)

MainModel 是我的中央数据模型。 ChildModel 有多种变体，它们解释了这里使用的多表继承。我已经能够使用这个模式声明来工作:

class BaseModelType(DjangoObjectType):
    class Meta:
        model = BaseModel

class ChildModelType(DjangoObjectType):
    class Meta:
        model = ChildModel

class MainModelType(DjangoObjectType):
    class Meta:
        model = MainModel

它允许以下 graphQL 查询:

{
  mainModel(id: 123) {
    id
    bases {
      id
      baseInfo
      childmodel {
        id
        name
      }
    }
  }
}

但是，我想以 Django 理解继承的方式将其展平，以便我可以像这样查询数据:

{
  mainModel(id: 123) {
    id
    bases {
      id
      baseInfo
      name        <--- this field from the child is now on the base level
    }
  }
}

我怀疑答案在于我如何声明 ChildModelType，但我一直无法弄清楚。任何提示表示赞赏!

Answer 1

您可以通过在 BaseModelType 类中声明附加字段和解析方法来实现:

class BaseModelType(DjangoObjectType):
    name_from_child = graphene.String()

    class Meta:
        model = BaseModel

    def resolve_name_from_child(self, info):
        # if ChildModel have ForeignKey to BaseModel
        # first_child = self.childmodel_set.first()

        # for your case with multi-table inheritance
        # ChildModel is derived from BaseModel: class ChildModel(BaseModel):
        first_child = self.childmodel

        if first_child:
            return first_child.name
        return None

查询:

{
  mainModel(id: 123) {
    id
    bases {
      id
      baseInfo
      name_from_child   <--- first child name
    }
  }
}