使用active_model_serializers序列化深层嵌套关联

Question

我正在使用Rails 4.2.1和active_model_serializers 0.10.0.rc2

我是API的新手并选择active_model_serializers因为它似乎成为rails的标准(虽然我不反对使用RABL或其他串行器)

我遇到的问题是我似乎无法在多级关系中包含各种属性.比如我有:

项目

class ProjectSerializer < ActiveModel::Serializer
  attributes                      :id, 
                                  :name,
                                  :updated_at

  has_many                        :estimates, include_nested_associations: true

end

和估计

class EstimateSerializer < ActiveModel::Serializer
  attributes                      :id, 
                                  :name, 
                                  :release_version, 
                                  :exchange_rate, 
                                  :updated_at,

                                  :project_id, 
                                  :project_code_id, 
                                  :tax_type_id 

  belongs_to                      :project
  belongs_to                      :project_code
  belongs_to                      :tax_type

  has_many                        :proposals

end

建议

class ProposalSerializer < ActiveModel::Serializer
  attributes                      :id, 
                                  :name, 
                                  :updated_at,

                                  :estimate_id

  belongs_to                      :estimate
end

当我点击/projects/1上面产生的时候:

{
  "id": 1,
  "name": "123 Park Ave.",
  "updated_at": "2015-08-09T02:36:23.950Z",
  "estimates": [
    {
      "id": 1,
      "name": "E1",
      "release_version": "v1.0",
      "exchange_rate": "0.0",
      "updated_at": "2015-08-12T04:23:38.183Z",
      "project_id": 1,
      "project_code_id": 8,
      "tax_type_id": 1
    }
  ]
}

但是,我想要它产生的是:

{
  "id": 1,
  "name": "123 Park Ave.",
  "updated_at": "2015-08-09T02:36:23.950Z",
  "estimates": [
    {
      "id": 1,
      "name": "E1",
      "release_version": "v1.0",
      "exchange_rate": "0.0",
      "updated_at": "2015-08-12T04:23:38.183Z",
      "project": { 
        "id": 1,
        "name": "123 Park Ave."
      },
      "project_code": {
        "id": 8,
        "valuation": 30
      },
      "tax_type": {
        "id": 1,
        "name": "no-tax"
      },
      "proposals": [
        {
          "id": 1,
          "name": "P1",
          "updated_at": "2015-08-12T04:23:38.183Z"
        },
        {
          "id": 2,
          "name": "P2",
          "updated_at": "2015-10-12T04:23:38.183Z"
        }
      ]
    }
  ]
}

理想情况下,我还希望能够指定每个序列化程序中包含的那些关联的属性,关联和属性.

我一直在研究AMS问题,似乎有一些关于应该如何处理的问题(或者如果甚至实际上支持这种功能)但是我很难搞清楚当前的情况国家是.

• https://github.com/rails-api/active_model_serializers/issues/835
• https://github.com/rails-api/active_model_serializers/issues/968
• https://github.com/rails-api/active_model_serializers/issues/414
• https://github.com/rails-api/active_model_serializers/issues/444

建议的解决方案之一是用一个方法来覆盖属性来调用嵌套属性,但这似乎被视为一个黑客,所以我想尽可能避免它.

无论如何,非常感谢如何进行此API或一般API建议的示例.

Answer 1

根据提交1426:https://github.com/rails-api/active_model_serializers/pull/1426 - 以及相关讨论,您可以看到默认的嵌套json和attributes序列化是一个级别.

如果您希望默认情况下进行深度嵌套,则可以在active_model_serializer初始值设定项中设置配置属性:

ActiveModelSerializers.config.default_includes = '**'

有关v0.10.6的详细参考:https://github.com/rails-api/active_model_serializers/blob/v0.10.6/docs/general/adapters.md#include-option

Answer 2

所以这不是最好的,甚至不是一个好的答案,但这是我需要它的工作方式.

虽然在将json_api适配器与AMS一起使用时似乎支持包含嵌套和侧载属性,但我需要支持flat json.此外,这种方法运行良好,因为每个序列化器都专门生成我需要它独立于任何其他序列化器而不需要在控制器中执行任何操作.

欢迎提供评论/替代方法.

项目模型

class Project < ActiveRecord::Base      
  has_many  :estimates, autosave: true, dependent: :destroy
end

ProjectsController

def index
  @projects = Project.all
  render json: @projects
end

ProjectSerializer

class ProjectSerializer < ActiveModel::Serializer
  attributes  :id, 
              :name,
              :updated_at,

              # has_many
              :estimates



  def estimates
    customized_estimates = []

    object.estimates.each do |estimate|
      # Assign object attributes (returns a hash)
      # ===========================================================
      custom_estimate = estimate.attributes


      # Custom nested and side-loaded attributes
      # ===========================================================
      # belongs_to
      custom_estimate[:project] = estimate.project.slice(:id, :name) # get only :id and :name for the project
      custom_estimate[:project_code] = estimate.project_code
      custom_estimate[:tax_type] = estimate.tax_type

      # has_many w/only specified attributes
      custom_estimate[:proposals] = estimate.proposals.collect{|proposal| proposal.slice(:id, :name, :updated_at)}

      # ===========================================================
      customized_estimates.push(custom_estimate)
    end

    return customized_estimates
  end
end

结果

[
  {
    "id": 1,
    "name": "123 Park Ave.",
    "updated_at": "2015-08-09T02:36:23.950Z",
    "estimates": [
      {
        "id": 1,
        "name": "E1",
        "release_version": "v1.0",
        "exchange_rate": "0.0",
        "created_at": "2015-08-12T04:23:38.183Z",
        "updated_at": "2015-08-12T04:23:38.183Z",
        "project": {
          "id": 1,
          "name": "123 Park Ave."
        },
        "project_code": {
          "id": 8,
          "valuation": 30,
          "created_at": "2015-08-09T18:02:42.079Z",
          "updated_at": "2015-08-09T18:02:42.079Z"
        },
        "tax_type": {
          "id": 1,
          "name": "No Tax",
          "created_at": "2015-08-09T18:02:42.079Z",
          "updated_at": "2015-08-09T18:02:42.079Z"
        },
        "proposals": [
          {
            "id": 1,
            "name": "P1",
            "updated_at": "2015-08-12T04:23:38.183Z"
          },
          {
            "id": 2,
            "name": "P2",
            "updated_at": "2015-10-12T04:23:38.183Z"
          }
        ]
      }
    ]
  }
]

我基本上无视尝试在序列化程序中实现任何has_many或belongs_to关联,只是定制了行为.我曾经slice选择特定的属性.希望更优雅的解决方案即将推出.

Answer 3

如果您使用的是JSONAPI适配器,则可以执行以下操作来呈现嵌套关系:

render json: @project, include: ['estimates', 'estimates.project_code', 'estimates.tax_type', 'estimates.proposals']

您可以从jsonapi文档中了解更多信息:http://jsonapi.org/format/#fetching-includes

Answer 4

您可以更改default_includes为ActiveModel::Serializer:

# config/initializers/active_model_serializer.rb
ActiveModel::Serializer.config.default_includes = '**' # (default '*')

另外,为了避免无限递归,可以控制嵌套序列化如下:

class UserSerializer < ActiveModel::Serializer
  include Rails.application.routes.url_helpers

  attributes :id, :phone_number, :links, :current_team_id

  # Using serializer from app/serializers/profile_serializer.rb
  has_one :profile
  # Using serializer described below:
  # UserSerializer::TeamSerializer
  has_many :teams

  def links
    {
      self: user_path(object.id),
      api: api_v1_user_path(id: object.id, format: :json)
    }
  end

  def current_team_id
    object.teams&.first&.id
  end

  class TeamSerializer < ActiveModel::Serializer
    attributes :id, :name, :image_url, :user_id

    # Using serializer described below:
    # UserSerializer::TeamSerializer::GameSerializer
    has_many :games

    class GameSerializer < ActiveModel::Serializer
      attributes :id, :kind, :address, :date_at

      # Using serializer from app/serializers/gamers_serializer.rb
      has_many :gamers
    end
  end
end

结果:

{
   "user":{
      "id":1,
      "phone_number":"79202700000",
      "links":{
         "self":"/users/1",
         "api":"/api/v1/users/1.json"
      },
      "current_team_id":1,
      "profile":{
         "id":1,
         "name":"Alexander Kalinichev",
         "username":"Blackchestnut",
         "birthday_on":"1982-11-19",
         "avatar_url":null
      },
      "teams":[
         {
            "id":1,
            "name":"Agile Season",
            "image_url":null,
            "user_id":1,
            "games":[
               {
                  "id":13,
                  "kind":"training",
                  "address":"",
                  "date_at":"2016-12-21T10:05:00.000Z",
                  "gamers":[
                     {
                        "id":17,
                        "user_id":1,
                        "game_id":13,
                        "line":1,
                        "created_at":"2016-11-21T10:05:54.653Z",
                        "updated_at":"2016-11-21T10:05:54.653Z"
                     }
                  ]
               }
            ]
         }
      ]
   }
}

Answer 5

在我的例子中,我在'MyApp/config/initializers'中创建了一个名为'active_model_serializer.rb'的文件,其中包含以下内容:

ActiveModelSerializers.config.default_includes = '**'

别忘了重启服务器:

$ rails s