Rails 5.2.1 - 模型和片段缓存

Question

我正在尝试在 Rails 5.2.1

中设置模型和片段缓存

我在片段缓存方面取得了成功，但在为我的模型实施模型缓存后，我仍然看到数据库查询。

我启用了开发缓存

$ rails dev:cache

模型助手

module LanguagesHelper
  def approved_languages
    Rails.cache.fetch("approved_languages") { Languages.is_active.is_approved }
  end
end

控制器

class LanguagesController < ApplicationController
  include LanguagesHelper

  def index
    @languages = approved_languages
  end
end

观看次数

app/views/languages/index.html.erb

<%= render partial: 'languages/language', collection: @languages, cached: true %>

app/views/languages/_language.html.erb

<% cache language do %>
  <%= language.name %>
<% end %>

控制台

Started GET "/languages" for 127.0.0.1 at 2018-08-21 14:13:29 -0400
Processing by LanguagesController#index as HTML
  Rendering languages/index.html.erb within layouts/application
  Language Load (1.2ms)  SELECT "languages".* FROM "languages" WHERE "languages"."deleted" =  AND "languages"."approved" =   [["deleted", false], ["approved", true]]
  ↳ app/views/languages/index.html.erb:4
  Rendered collection of languages/_language.html.erb [1 / 1 cache hits] (3.0ms)
  Rendered languages/index.html.erb within layouts/application (10.9ms)
Completed 200 OK in 50ms (Views: 46.2ms | ActiveRecord: 1.2ms)

为什么每次请求时我仍然看到数据库查询？

Answer 1

这里似乎发生的事情是您在加载记录之前缓存关系 ，因此它仍然必须在可以使用之前实际加载它们（使用我的广告模型，因为它在那里并且方便在 irb 中进行测试）：

ads = Ad.all;nil # no query here, this is what I think you're caching # this next line is where the query is run, (this would be # equivalent to your render line) ads.each { ... } # Ad Load (0.1ms) SELECT "ads".* FROM "ads"

相反，您可以尝试在缓存关系之前强制活动记录加载关系，看看是否有帮助。您可以使用 load:

ads = Ad.all.load;nil # query is now run here # Ad Load (0.1ms) SELECT "ads".* FROM "ads" ads.each { ... } # and not run here

并启用缓存（全部在单个 rails 控制台会话中，多个会话似乎忘记了之前的缓存，但我没有配置缓存，所以可能只是内存中的存储某种）

ads = Rails.cache.fetch("test load") { Ad.all.load };nil # query # Ad Load (0.9ms) SELECT "ads".* FROM "ads" ads = Rails.cache.fetch("test load") { Ad.all.load };nil # no query ads.each { } # no query ads = Rails.cache.fetch("test without load") { Ad.all };nil # no query ads.each { };nil # query # Ad Load (0.1ms) SELECT "ads".* FROM "ads" ads = Rails.cache.fetch("test without load") { Ad.all };nil # no query ads.each { };nil # query # Ad Load (0.1ms) SELECT "ads".* FROM "ads"

Answer 2

我之前很接近，但现在已经成功实现了缓存。上面的答案很受欢迎，但不是我想要的，这是我当前的设置。

我本应将语言模型查询移动到模型中，却在助手模块中调用它。

型号

after_save :clear_cache
after_destroy :clear_cache

def clear_language_cache
  Rails.cache.delete('Language.active.approved')
end

def self.active_approved
  Rails.cache.fetch('Language.active.approved') { is_active.is_approved.order(created_at: :desc).to_a }
end

控制器

class LanguagesController < ApplicationController
  def index
    @languages = Language.active_approved
  end
end

控制台

Started GET "/languages" for 127.0.0.1 at 2018-08-22 18:13:21 -0400
Processing by LanguagesController#index as HTML
  Rendering languages/index.html.erb within layouts/application
  Rendered collection of languages/_language.html.erb [1 / 1 cache hits] (11.0ms)
  Rendered languages/index.html.erb within layouts/application (15.9ms)
Completed 200 OK in 68ms (Views: 45.5ms | ActiveRecord: 5.8ms)

Rails 5.2.1 - 模型和片段缓存

Rails 5.2.1 - Model & Fragment Caching

ruby-on-rails

ruby

ruby-on-rails-5

memorycache

fragment-caching