Refactor counters to use `counter_cache`

app/models/answer.rb

@@ -1,8 +1,8 @@
 class Answer < ApplicationRecord
   extend Answer::TimelineMethods
 
-  belongs_to :user
+  belongs_to :user, counter_cache: :answered_count
-  belongs_to :question
+  belongs_to :question, counter_cache: :answer_count
   has_many :comments, dependent: :destroy
   has_many :smiles, class_name: "Appendable::Reaction", foreign_key: :parent_id, dependent: :destroy
   has_many :subscriptions, dependent: :destroy
@@ -18,15 +18,12 @@ class Answer < ApplicationRecord
 
   SHORT_ANSWER_MAX_LENGTH = 640
 
-  # rubocop:disable Rails/SkipsModelValidations
   after_create do
     Inbox.where(user: self.user, question: self.question).destroy_all
 
     Notification.notify self.question.user, self unless self.question.user == self.user or self.question.user.nil?
     Subscription.subscribe self.user, self
     Subscription.subscribe self.question.user, self unless self.question.author_is_anonymous
-    user.increment! :answered_count
-    question.increment! :answer_count
   end
 
   before_destroy do
@@ -39,19 +36,15 @@ class Answer < ApplicationRecord
       end
     end
 
-    user&.decrement! :answered_count
-    question&.decrement! :answer_count
     self.smiles.each do |smile|
       Notification.denotify self.user, smile
     end
     self.comments.each do |comment|
-      comment.user&.decrement! :commented_count
       Subscription.denotify comment, self
     end
     Notification.denotify question&.user, self
     Subscription.destruct self
   end
-  # rubocop:enable Rails/SkipsModelValidations
 
   def notification_type(*_args)
     Notification::QuestionAnswered

app/models/comment.rb

@@ -1,18 +1,15 @@
 class Comment < ApplicationRecord
-  belongs_to :user
+  belongs_to :user, counter_cache: :commented_count
-  belongs_to :answer
+  belongs_to :answer, counter_cache: :comment_count
   validates :user_id, presence: true
   validates :answer_id, presence: true
   has_many :smiles, class_name: "Appendable::Reaction", foreign_key: :parent_id, dependent: :destroy
 
   validates :content, length: { maximum: 512 }
 
-  # rubocop:disable Rails/SkipsModelValidations
   after_create do
     Subscription.subscribe self.user, answer, false
     Subscription.notify self, answer
-    user.increment! :commented_count
-    answer.increment! :comment_count
   end
 
   before_destroy do
@@ -25,10 +22,7 @@ class Comment < ApplicationRecord
     end
 
     Subscription.denotify self, answer
-    user&.decrement! :commented_count
-    answer&.decrement! :comment_count
   end
-  # rubocop:enable Rails/SkipsModelValidations
 
   def notification_type(*_args)
     Notification::Commented