计算字段的主动模型序列化程序缓存

Question

我正在尝试缓存一个项目集合，这是我的AMS：

class ApplicationCategorySerializer < ActiveModel::Serializer

  cache({})
  cache key: 'application_category', expires_in: 3.days

  attributes :id
  attributes :name
  attributes :active
  attributes :group
  attributes :num_of_protocols

  belongs_to :group do |serializer|
    serializer.attributes[:group][:name]
  end


  def num_of_protocols
    ApplicationCategory.find(object.id).protocol_categories.count
  end
end

我的问题是，如果没有:num_of_protocols部分，生成响应需要10倍的速度，

当我查看日志时，我可以看到：

Started GET "/application_categories.json" for 127.0.0.1 at 2016-08-04 19:12:27 +0300
Processing by ApplicationCategoriesController#index as JSON
  ApplicationCategory Load (3.0ms)  SELECT "application_categories".* FROM "application_categories"
[active_model_serializers]   Group Load (1.0ms)  SELECT  "groups".* FROM "groups" WHERE "groups"."id" = ? LIMIT 1  [["id", 2066]]
[active_model_serializers]   ApplicationCategory Load (0.0ms)  SELECT  "application_categories".* FROM "application_categories" WHERE "application_categories"."id" = ? LIMIT 1  [["id", 1]]
[active_model_serializers]    (0.0ms)  SELECT COUNT(*) FROM "protocol_categories" INNER JOIN "application_categories_protocol_categories" ON "protocol_categories"."id" = "application_categories_protocol_categories"."protocol_category_id" WHERE "application_categories_protocol_categories"."application_category_id" = ?  [["application_category_id", 1]]
[active_model_serializers]   CACHE (0.0ms)  SELECT  "groups".* FROM "groups" WHERE "groups"."id" = ? LIMIT 1  [["id", 2066]]
[active_model_serializers]   ApplicationCategory Load (0.0ms)  SELECT  "application_categories".* FROM "application_categories" WHERE "application_categories"."id" = ? LIMIT 1  [["id", 2]]
[active_model_serializers]    (0.0ms)  SELECT COUNT(*) FROM "protocol_categories" INNER JOIN "application_categories_protocol_categories" ON "protocol_categories"."id" = "application_categories_protocol_categories"."protocol_category_id" WHERE "application_categories_protocol_categories"."application_category_id" = ?  [["application_category_id", 2]]
[active_model_serializers]   CACHE (0.0ms)  SELECT  "groups".* FROM "groups" WHERE "groups"."id" = ? LIMIT 1  [["id", 2066]]
...................... [many many more lines like those...]
[active_model_serializers]   CACHE (0.0ms)  SELECT  "application_categories".* FROM "application_categories" WHERE "application_categories"."id" = ? LIMIT 1  [["id", 608]]
[active_model_serializers]   CACHE (0.0ms)  SELECT COUNT(*) FROM "protocol_categories" INNER JOIN "application_categories_protocol_categories" ON "protocol_categories"."id" = "application_categories_protocol_categories"."protocol_category_id" WHERE "application_categories_protocol_categories"."application_category_id" = ?  [["application_category_id", 608]]
[active_model_serializers]   CACHE (0.0ms)  SELECT  "application_categories".* FROM "application_categories" WHERE "application_categories"."id" = ? LIMIT 1  [["id", 609]]
[active_model_serializers]   CACHE (0.0ms)  SELECT COUNT(*) FROM "protocol_categories" INNER JOIN "application_categories_protocol_categories" ON "protocol_categories"."id" = "application_categories_protocol_categories"."protocol_category_id" WHERE "application_categories_protocol_categories"."application_category_id" = ?  [["application_category_id", 609]]
[active_model_serializers]   CACHE (0.0ms)  SELECT  "application_categories".* FROM "application_categories" WHERE "application_categories"."id" = ? LIMIT 1  [["id", 610]]
[active_model_serializers]   CACHE (0.0ms)  SELECT COUNT(*) FROM "protocol_categories" INNER JOIN "application_categories_protocol_categories" ON "protocol_categories"."id" = "application_categories_protocol_categories"."protocol_category_id" WHERE "application_categories_protocol_categories"."application_category_id" = ?  [["application_category_id", 610]]
[active_model_serializers] Rendered ActiveModel::Serializer::CollectionSerializer with ActiveModelSerializers::Adapter::Attributes (1521.15ms)

如何使用缓存获得更好的结果？-当我注释掉cache行时，我得到了aprox。与使用它们时相同的时间，当我删除:num_of_protocols时，我在&没有缓存的情况下获得相同的时间。

我的配置有什么错误？

Answer 1

你能做到吗？

def num_of_protocols
  object.protocol_categories.count
end

而且，序列化程序对我来说已经有一段时间了，但我认为你可以做到这一点…

def num_of_protocols
  protocol_categories.count
end

这是更好的ruby (在这种情况下，protocal_categories已经作为数组加载)

def num_of_protocols
  protocol_categories.size
end

而且，如果所有这些都有效或无效，请确保在呈现到json之前实例化@application_category时包含protocol_categories和groups。您执行的查询太多。