trick_serial

Trick Serializers using Proxies

Serialize objects using Proxies to trick serializers (e.g.: Marshal) to not store entire object graphs (e.g.: ActiveRecord object).

trick_serial supports CGI::Session and Rack sessions to allow ActiveRecord::Base objects to be stored directly in a session. If the object has an id, it is stored in the session as a proxy object composed of the object’s class name and id. The object is restored from the database only if referenced through the session.

trick_serial can be used independently of ActiveRecord and Session. It can be configured to use serialization proxies for any classes.

trick_serial maintains object identity during serialization.

Features

Support for CGI::Session::FileStore, CGI::Session::PStore and Rails 1.2 CGI::Session::MemCacheStore.

Usage

ActionController session example

module AuthenticatedController
  def user
    # User.find(...) is executed on the demand of session[:user].
    @user ||= session[:user] 
  end

  def user= x
    # [ x.class.name, x.id ] is serialized in place of User object in session[:user].
    @user = session[:user] = x 
  end
end

class UserController < ActionController::Base
  include AuthenticatedController

  def login
    if u = User.find(:first, :conditions => [ 'name = ? AND password = ?', params[:login], params[:password] ])
       self.user = u
       redirect_to :action => :home
    end
  end

  def logout
     self.user = nil
     redirect_to :action => :login
  end

  def home
    render :text => "You are #{user ? user.login : "NOT LOGGED IN!"}"
  end

  def update
    raise unless user
    user.attributes = params[:user]
    user.save!
  end
end

Configuration

Rails 1.2

Inside your Rails::Initializer block:

Rails::Initializer.run do |config|
  ...
  # Configure trick_serial for Rails 1.2 MemCache Sessions:
  begin
    require 'action_controller/session/mem_cache_store'
    require 'trick_serial/serializer'
    require 'trick_serial/serializer/cgi_session'

    # This must be done after all session-related code is loaded:
    TrickSerial::Serializer::CgiSession.activate!

    # Create a serializer instance.
    serializer = TrickSerial::Serializer.new

    # Enable logging:
    if false
      serializer.logger = Log4r::Logger[:mylogger]
      serializer.logger_level = :debug
    end

    # Instruct the serializer to create proxies for instances of any subclasses of:
    serializer.proxy_class_map = { 
      ActiveRecord::Base => TrickSerial::Serializer::ActiveRecordProxy,
    }

    # Options used in CGI::Session.new(@cgi, options) from ActionController::Base.
    # See ActionController::SessionManagement for details.
    ActionController::CgiRequest::DEFAULT_SESSION_OPTIONS.
      merge!({
               'database_manager' => TrickSerial::Serializer::CgiSession::Store,
               'TrickSerial.database_manager' => ::CGI::Session::MemCacheStore,
               'TrickSerial.serializer' => serializer,
               'TrickSerial.logger' => Log4r::Logger[:mylogger],
               'TrickSerial.logger_level' => :info,
             })
  end
  config.action_controller.session_store = TrickSerial::Serializer::CgiSession::Store
  ...
end

Rails 3

COMING SOON!

Contributing to trick_serial

Check out the latest master to make sure the feature hasn’t been implemented or the bug hasn’t been fixed yet
Check out the issue tracker to make sure someone already hasn’t requested it and/or contributed it
Fork the project
Start a feature/bugfix branch
Commit and push until you are happy with your contribution
Make sure to add tests for it. This is important so I don’t break it in a future version unintentionally.
Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.