有没有办法通过使用 Rails 中的 Fast JSON API 来 select 只是外部对象的一个​​属性？

Question

我正在创建一个使用后端 Rails API 的旅行应用程序。我决定使用 Fast JSON API 来序列化我的数据。我有一个国家名单；每个国家都有很多城市，每个城市都有很多景点。

这些是我的模型之间的关联列表。

Country.rb 
has_many :cities
has_many :attractions, through: :locality

Localities.rb
has_many :attractions
belongs_to :country

Attraction.rb
belongs_to :locality

当我为一个单独的景点序列化我的数据时，我想只包括城市的名称属性和它所属国家的名称属性。我目前正在通过添加可选参数以包含地区和国家名称来执行此操作。

  def show
    attraction = Attraction.find_by(slug: params[:slug])
    options = {}
    options[:include] = [:locality, :'locality.country.name']
    render json: AttractionSerializer.new(attraction, options).serialized_json
  end

然而，这给出了国家的所有属性和关系，包括嵌套在国家内的所有不相关地点的列表，当我的数据集变大时，这将变得非常低效。见下文：

{
"data": {
    "id": "1",
    "type": "attraction",
    "attributes": {
        "name": "Plaza de España",
        "description": "Site of the World Exposition in 1929",
        "types": null,
        "latitude": 40.4232824,
        "longitude": -3.7107257,
        "slug": "plaza-de-espana",
        "locality": {
            "id": 1,
            "name": "Seville",
            "country_id": 168,
            "created_at": "2020-06-10T05:43:47.474Z",
            "updated_at": "2020-06-10T05:43:47.474Z",
            "slug": "seville",
            "latitude": 37.3886303,
            "longitude": -5.9953403
        }
    },
    "relationships": {
        "locality": {
            "data": {
                "id": "1",
                "type": "locality"
            }
        }
    }
},
"included": [
    {
        "id": "1",
        "type": "locality",
        "attributes": {
            "name": "Seville",
            "latitude": 37.3886303,
            "longitude": -5.9953403,
            "slug": "seville"
        },
        "relationships": {
            "country": {
                "data": {
                    "id": "168",
                    "type": "country"
                }
            }
        }
    },
    {
        "id": "168",
        "type": "country",
        "attributes": {
            "name": "Spain",
            "slug": "spain",
            "iso_3166_1_alpha2": "ES",
            "iso_3166_1_alpha3": "ESP",
            "iso_3166_1_numeric": "724"
        },
        "relationships": {
            "localities": {
                "data": [
                    {
                        "id": "1",
                        "type": "locality"
                    },
                    {
                        "id": "2",
                        "type": "locality"
                    },
                    {
                        "id": "3",
                        "type": "locality"
                    },
                    {
                        "id": "4",
                        "type": "locality"
                    },
                    {
                        "id": "5",
                        "type": "locality"
                    },
                    {
                        "id": "6",
                        "type": "locality"
                    }
                ]
            },
            "attractions": {
                "data": [
                    {
                        "id": "1",
                        "type": "attraction"
                    }
                ]
            }
        }
    }
]

}

有没有办法在景点 JSON 中只包含一个属性（即国家名称），而不是整个对象？ （景点嵌套在国家以下两层）

非常感谢。

Answer 1

您需要创建多个协同工作的序列化程序来实现此目的。

class AttractionSerializer
      include FastJsonapi::ObjectSerializer

      attributes :attraction_attr_1, :attraction_attr_2, etc.

      belongs_to :locality, serializer: AttractionLocalitySerializer
end

class AttractionLocalitySerializer
      include FastJsonapi::ObjectSerializer

      attributes :name

      belongs_to :country, serializer: AttractionCountrySerializer
end

class AttractionCountrySerializer
      include FastJsonapi::ObjectSerializer

      attributes :name
end