Caching

Gemfile

@@ -61,6 +61,8 @@ gem 'mini_racer'
 
 gem 'unicorn'
 
+gem 'redis-rails'
+
 group :development, :test do
   gem 'rspec-rails', '~> 5.0.0'
   gem 'factory_bot_rails'

Gemfile.lock

@@ -330,6 +330,22 @@ GEM
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     redis (4.1.4)
+    redis-actionpack (5.2.0)
+      actionpack (>= 5, < 7)
+      redis-rack (>= 2.1.0, < 3)
+      redis-store (>= 1.1.0, < 2)
+    redis-activesupport (5.2.1)
+      activesupport (>= 3, < 7)
+      redis-store (>= 1.3, < 2)
+    redis-rack (2.1.3)
+      rack (>= 2.0.8, < 3)
+      redis-store (>= 1.2, < 2)
+    redis-rails (5.0.2)
+      redis-actionpack (>= 5.0, < 6)
+      redis-activesupport (>= 5.0, < 6)
+      redis-store (>= 1.2, < 2)
+    redis-store (1.9.0)
+      redis (>= 4, < 5)
     regexp_parser (2.1.1)
     request_store (1.5.0)
       rack (>= 1.4)
@@ -515,6 +531,7 @@ DEPENDENCIES
   rack-mini-profiler (~> 2.0)
   rails (~> 6.1.3, >= 6.1.3.1)
   rails-controller-testing
+  redis-rails
   rspec-rails (~> 5.0.0)
   rubocop
   rubocop-performance

app/helpers/application_helper.rb

@@ -1,2 +1,8 @@
 module ApplicationHelper
+  def collection_cache_helper_for(model)
+    klass = model.to_s.capitalize.constantize
+    count = klass.count
+    max_updated_at = klass.maximum(:updated_at).try(:utc).try(:to_s, :number)
+    "#{model.to_s.pluralize}/collection-#{count}-#{max_updated_at}"
+  end
 end

app/models/answer.rb

@@ -3,7 +3,7 @@ class Answer < ApplicationRecord
   include Votable
   include Commentable
 
-  belongs_to :question
+  belongs_to :question, touch: true
   belongs_to :author, class_name: 'User', foreign_key: 'user_id'
 
   has_many_attached :files

app/models/comment.rb

@@ -1,6 +1,6 @@
 class Comment < ApplicationRecord
   belongs_to :user
-  belongs_to :commentable, polymorphic: true
+  belongs_to :commentable, polymorphic: true, touch: true
 
   validates :body, presence: true
 

app/models/link.rb

@@ -1,5 +1,5 @@
 class Link < ApplicationRecord
-  belongs_to :linkable, polymorphic: true
+  belongs_to :linkable, polymorphic: true, touch: true
 
   validates :name, presence: true
   validates :url, presence: true, url: { no_local: true }

app/views/answers/_answer.html.slim

@@ -1,36 +1,37 @@
-li.answer id="answer-#{answer.id}"
-  .answer-errors
-    = render 'shared/errors'
+- cache answer do
+  li.answer id="answer-#{answer.id}"
+    .answer-errors
+      = render 'shared/errors'
 
-  div 
-    = "Author: #{answer.author.email}"
-  div 
-    = answer.body
+    div 
+      = "Author: #{answer.author.email}"
+    div 
+      = answer.body
 
-  .answer-links
-    = render answer.links
+    .answer-links
+      = render answer.links
 
-  div
-    - if answer.files.attached?
-      = render partial: 'attachments/attachment', collection: answer.files
-
-  div id="votable-answer-#{answer.id}"
-    = render 'votes/rating', votable: answer
-    - if signed_in? && can?(:create_vote, answer)
-      = render 'votes/vote', vote: answer.vote_of(current_user), votable: answer
-
-  - if can?(:destroy, answer)
-    div
-      = link_to 'Delete answer', answer_path(answer), method: :delete, remote: true
-  - if can?(:update, answer)
     div
-      = link_to 'Edit answer', '#', class: 'edit-answer-link', data: { answer_id: answer.id }
+      - if answer.files.attached?
+        = render partial: 'attachments/attachment', collection: answer.files
+
+    div id="votable-answer-#{answer.id}"
+      = render 'votes/rating', votable: answer
+      - if signed_in? && can?(:create_vote, answer)
+        = render 'votes/vote', vote: answer.vote_of(current_user), votable: answer
 
-  div.hidden
-    = render partial: '/answers/answer_form', locals: { answer: answer, html_data: { id: "edit-answer-#{answer.id}" } }
+    - if can?(:destroy, answer)
+      div
+        = link_to 'Delete answer', answer_path(answer), method: :delete, remote: true
+    - if can?(:update, answer)
+      div
+        = link_to 'Edit answer', '#', class: 'edit-answer-link', data: { answer_id: answer.id }
 
-  -if can?(:mark_best, answer)
-    div
-      = link_to 'Best answer', mark_best_answer_path(answer), method: :patch, class: 'best-answer-link', remote: true
+    div.hidden
+      = render partial: '/answers/answer_form', locals: { answer: answer, html_data: { id: "edit-answer-#{answer.id}" } }
+
+    -if can?(:mark_best, answer)
+      div
+        = link_to 'Best answer', mark_best_answer_path(answer), method: :patch, class: 'best-answer-link', remote: true
 
-  = render "comments/comments", commentable: answer
+    = render "comments/comments", commentable: answer

app/views/answers/_answer_form.html.slim

@@ -1,15 +1,16 @@
-= form_with model: answer, html: try(:html_data) || {}, local: false do |f|
-  div
-    = f.label :body
-  div
-    = f.text_area :body
+- cache answer do 
+  = form_with model: answer, html: try(:html_data) || {}, local: false do |f|
+    div
+      = f.label :body
+    div
+      = f.text_area :body
 
-  = render 'links/links_form', f: f
+    = render 'links/links_form', f: f
 
-  div
-    = f.label :files
-  div
-    = f.file_field :files, multiple: true, direct_upload: true
+    div
+      = f.label :files
+    div
+      = f.file_field :files, multiple: true, direct_upload: true
 
-  div 
-    = f.submit 'Answer'
+    div 
+      = f.submit 'Answer'

app/views/comments/_comment.html.slim

@@ -1,2 +1,3 @@
-div id="comment-#{comment.id}"
-  = comment.body
+- cache comment do
+  div id="comment-#{comment.id}"
+    = comment.body

app/views/links/_link_fields.html.slim

@@ -1,8 +1,9 @@
-.nested-fields
-  .field
-    div = f.label :name
-    div = f.text_field :name
-  .field
-    div = f.label :url
-    div = f.text_field :url
-  = link_to_remove_association "Remove link", f
+- cache f do
+  .nested-fields
+    .field
+      div = f.label :name
+      div = f.text_field :name
+    .field
+      div = f.label :url
+      div = f.text_field :url
+    = link_to_remove_association "Remove link", f

app/views/questions/_question_form.html.slim

@@ -1,18 +1,19 @@
-= form_with model: question, local: local do |f|
-  div = f.label :title
-  div = f.text_field :title
+- cache question do
+  = form_with model: question, local: local do |f|
+    div = f.label :title
+    div = f.text_field :title
 
-  div = f.label :body
-  div = f.text_area :body
+    div = f.label :body
+    div = f.text_area :body
 
-  = render 'links/links_form', f: f
+    = render 'links/links_form', f: f
 
-  div = f.label :files
-  div = f.file_field :files, multiple: true, direct_upload: true
+    div = f.label :files
+    div = f.file_field :files, multiple: true, direct_upload: true
 
-  .award
-    h3 Award for the best answer 
-    = f.fields_for :award do |award_f|
-      = render 'awards/award_fields', f: award_f
+    .award
+      h3 Award for the best answer 
+      = f.fields_for :award do |award_f|
+        = render 'awards/award_fields', f: award_f
 
-  div = f.submit 'Ask' 
+    div = f.submit 'Ask' 

app/views/questions/_question_full.html.slim

@@ -1,37 +1,38 @@
-div.question id="question-#{question.id}"
-  .question-errors
-    = render 'shared/errors'
-
-  h4 = "Title: #{question.title}"
-  div = "Author: #{question.author.email}"
-  div = question.body
-
-  .question-links
-    = render question.links
-
-  -if question.files.attached?
-    = render partial: 'attachments/attachment', collection: question.files
-
-  div id="votable-question-#{question.id}"
-    = render 'votes/rating', votable: question
-    - if signed_in? && can?(:create_vote, question)
-      = render 'votes/vote', vote: question.vote_of(current_user), votable: question
-
-  - if signed_in?
-    = render 'subscriptions/subscription', question: question
-
-  - if question.award.present?
-    .question-award
-      h3 = "For the best answer you will receive #{question.award.name}"
-      .question-award-image
-        = image_tag question.award.image, size:"250x250"
-
-  - if can?(:destroy, question)
-    div = link_to 'Delete question', question_path(question), method: :delete
-  - if can?(:update, question)
-    div = link_to 'Edit question', '#', class: 'edit-question-link', data: { question_id: question.id }
-
-  div.hidden
-    = render 'question_form', question: question, local: false
-
-  = render "comments/comments", commentable: question
+- cache question do
+  div.question id="question-#{question.id}"
+    .question-errors
+      = render 'shared/errors'
+
+    h4 = "Title: #{question.title}"
+    div = "Author: #{question.author.email}"
+    div = question.body
+
+    .question-links
+      = render question.links
+
+    -if question.files.attached?
+      = render partial: 'attachments/attachment', collection: question.files
+
+    div id="votable-question-#{question.id}"
+      = render 'votes/rating', votable: question
+      - if signed_in? && can?(:create_vote, question)
+        = render 'votes/vote', vote: question.vote_of(current_user), votable: question
+
+    - if signed_in?
+      = render 'subscriptions/subscription', question: question
+
+    - if question.award.present?
+      .question-award
+        h3 = "For the best answer you will receive #{question.award.name}"
+        .question-award-image
+          = image_tag question.award.image, size:"250x250"
+
+    - if can?(:destroy, question)
+      div = link_to 'Delete question', question_path(question), method: :delete
+    - if can?(:update, question)
+      div = link_to 'Edit question', '#', class: 'edit-question-link', data: { question_id: question.id }
+
+    div.hidden
+      = render 'question_form', question: question, local: false
+
+    = render "comments/comments", commentable: question

app/views/questions/index.html.slim

@@ -3,5 +3,6 @@ h1 Questions
 p= link_to 'Ask question', new_question_path
 
 ul.questions
-  - @questions.each do |question|
-    li = render question
+  - cache collection_cache_helper_for(:question)
+    - @questions.each do |question|
+      li = render question

config/application.rb

@@ -18,6 +18,7 @@ class Application < Rails::Application
     #
     # config.time_zone = "Central Time (US & Canada)"
     # config.eager_load_paths << Rails.root.join("extras")
+    config.cache_store = :redis_store, 'redis://localhost:6379/0/cache', { expires_in: 90.minutes }
 
     config.generators do |g|
       g.test_framework :rspec,

config/environments/development.rb

@@ -25,7 +25,8 @@
       'Cache-Control' => "public, max-age=#{2.days.to_i}"
     }
   else
-    config.action_controller.perform_caching = false
+    config.action_controller.perform_caching = true
+    config.action_controller.enable_fragment_cache_logging = true
 
     config.cache_store = :null_store
   end