How to store temporary data and share it with your background processor

In my current project, I had to store some temporary data for a user and let a few background processors have access to it. I wrote something small with a dependency on Redis which does the job.

It allows me to use current_user.tmp[:token_id] = "somedata here" and then access it in the background processor using user.tmp[:token_id] which I think is pretty neat.

Moreover, since my use case needed this for temporary storage, I set it to auto expire in 1 day. If yours is different you could change that piece of code.

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# /app/models/user_tmp.rb
class UserTmp
  attr_reader :user
  def initialize(user)
    @user = user
  end

  EXPIRATION_SECONDS = 1.day
  SERIALIZER = Marshal

  def [](key)
    serialized_val = Redis.current.get(namespaced_key(key))
    SERIALIZER.load(serialized_val) if serialized_val
  end
  def []=(key, val)
    serialized_val = SERIALIZER.dump(val)
    Redis.current.setex(namespaced_key(key), EXPIRATION_SECONDS, serialized_val)
  end

  private
  def namespaced_key(key)
    "u:#{user.id}:#{key}"
  end
end

And here is the user class

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# /app/models/user.rb
class User < ActiveRecord::Base
  #...

  def tmp
    @tmp ||= UserTmp.new(self)
  end

  #...
end

Hope you find it useful :)

I am currently working on LiveForm which makes setting up contact forms on your website a breeze.