Rails6 Redis Session Store (serializer by JSON)

session_store.rb

# -*- encoding : utf-8 -*-
Rails.application.config.session_store(
  :redis_store,
  key: "_#{Rails.application.class.parent_name.downcase}_session",
  expire_after: 2.days,
  threadsafe: true,
  url: "redis://127.0.0.1:6379/8",
)

# Redis session store(serializer by JSON) for Rails 6
# need redis / hiredis gem

module ActionDispatch
  module Session
    class RedisStore < AbstractSecureStore
      def initialize(app, options = {})
        redis_options = {
          driver: options[:driver] || :hiredis,
          threadsafe: options.has_key?(:threadsafe) ? options[:threadsafe] : true,
        }
        if options.has_key?(:cluster)
          redis_options[:cluster] = options[:cluster]
        else
          redis_options[:url] = options[:url] || "redis://127.0.0.1:6379/8"
        end
        @redis_client = Redis.new(redis_options)
        @expire_in = options[:expire_after] || options[:expires_in] || 2.days
        @namespace = options[:namespace] || options[:key]
        super
      end
    
      # Get a session from the cache.
      def find_session(env, sid)
        unless sid && (session = get_session_with_fallback(sid))
          sid, session = generate_sid, {}
        end
        [sid, session]
      end
    
      # Set a session in the cache.
      def write_session(env, sid, session, options)
        key = cache_key(sid.private_id)
        if session
          @redis_client.set(key, JSON.dump(session), ex: @expire_in)
        else
          @redis_client.del(key)
        end
        sid
      end
    
      # Remove a session from the cache.
      def delete_session(env, sid, options)
        @redis_client.del(cache_key(sid.private_id))
        @redis_client.del(cache_key(sid.public_id))
        generate_sid
      end
    
      private
        # Turn the session id into a cache key.
        def cache_key(id)
          "_#{@namespace}:session_id:#{id}"
        end
    
        def get_session_with_fallback(sid)
          raw_data = @redis_client.get(cache_key(sid.private_id)) || @redis_client.get(cache_key(sid.public_id))
          return JSON.parse(raw_data)
        end
    end
  end
end