Find a best way to work with redis cache on rails

Question

I try to use Redis to cache on rails, but I get a challenge when trying to cache multi-language. Because my Redis needs to be cached with table_translations

I try with some code, but I don't think this is the best way

I have the instance variable to work with Erb template

def index
  @posts = fetch_posts
  @translations = fetch_translations

  puts @posts
  puts @translations
end

and Redis fetch like this

private
  def fetch_posts
    begin
      posts = $redis.get "posts"

      if posts.nil?
        posts = []

        Post.all.order("id ASC").each do |post|
          posts << post
        end

        posts = posts.to_json

        $redis.set "posts", posts
      end

      posts = JSON.load posts
    rescue => error
      puts error.inspect
      posts = Post.all
    end
    posts
  end

  def fetch_translations
    begin
      translations = $redis.get "translations"

      if translations.nil?

        translations = []

        Post.all.order("id ASC").each do |post|
          post.translations.order("locale ASC").each do |translation|
            translations << translation
          end
        end

        translations = translations.to_json

        $redis.set "translations", translations
      end

      translations = JSON.load translations
    rescue => error
      puts error.inspect
      translations = Post.all
    end
    translations
  end

I do that because I need to get all language version of a post, so I make a Redis key for translate

and my output:

{"id":1,"slug":"hello-world","thumb_url":"thumbs/null","thumb_file_name":null,"thumb_content_type":null,"thumb_file_size":null,"thumb_updated_at":null,"featured":false,"hidden":false,"created_at":"2019-04-18T07:05:09.117Z","updated_at":"2019-04-18T07:27:55.830Z"}
{"title":"Xin chao","description":"Day la bai viet dau tien, duoc viet tu rails CMS","body":"xin chao cac ban"}
{"title":"Hello World","description":"This is first post from rails CMS","body":"Hello every body"}

I find the best solution to make my output into a key, like this:

{"id":1,"slug":"hello-world","thumb_url":"thumbs/null","thumb_file_name":null,"thumb_content_type":null,"thumb_file_size":null,"thumb_updated_at":null,"featured":false,"hidden":false,"created_at":"2019-04-18T07:05:09.117Z","updated_at":"2019-04-18T07:27:55.830Z","title":"Xin chao","description":"Đay la bai viet đau tien, đuoc viet tu rails CMS","body":"xin chao cac ban"}
{"id":1,"slug":"hello-world","thumb_url":"thumbs/null","thumb_file_name":null,"thumb_content_type":null,"thumb_file_size":null,"thumb_updated_at":null,"featured":false,"hidden":false,"created_at":"2019-04-18T07:05:09.117Z","updated_at":"2019-04-18T07:27:55.830Z",title":"Hello World","description":"This is first post from rails CMS","body":"Hello every body"}

My code can work correctly, but I need your help to make it better, please help me to improve my skills

Thank for your help

Answer 1

You can use the built in Rails cache handler, this way you won't need to handle .nil? calls to cache keys.

  private

  def fetch_posts
    posts = Rails.cache.fetch("posts") do
      begin
        Post.all.order("id ASC").as_json
      rescue => error
        puts error.inspect
        Post.all
      end
    end
    posts
  end

  def fetch_translations
    translations = Rails.cache.fetch("translations") do
      begin
        Post.all.order("id ASC").map do |post|
          post.translations.order("locale ASC").as_json
        end.flatten
      rescue => error
        puts error.inspect
        Post.all
      end
    end
    translations
  end

Answer 2

I found the solution by follow this stuff How do you add an array to another array in Ruby and not end up with a multi-dimensional result?

concept is flatten all attr in two array and then Hash again this into new array

def fetch_posts
  posts = []

  Post.all.order("id ASC").each do |post|
    post.translations.each do |translation|
      posts << [*post.attributes.slice('slug','thumb_url'),*JSON.parse(translation.to_json)].to_h
    end
  end
end

Hope this help to anyone have question same to me :)