class ActiveRecord::SessionStore

Active Record Session Store

A session store backed by an Active Record class. A default class is provided, but any object duck-typing to an Active Record Session class with text session_id and data attributes is sufficient.

The default assumes a sessions tables with columns:

+id+ (numeric primary key),
+session_id+ (string, :limit => 255), and
+data+ (text or longtext; careful if your session data exceeds 65KB).

The session_id column should always be indexed for speedy lookups. Session data is marshaled to the data column in Base64 format. If the data you write is larger than the column's size limit, ActionController::SessionOverflowError will be raised.

You may configure the table name, primary key, and data column. For example, at the end of config/application.rb:

ActiveRecord::SessionStore::Session.table_name = 'legacy_session_table'
ActiveRecord::SessionStore::Session.primary_key = 'session_id'
ActiveRecord::SessionStore::Session.data_column_name = 'legacy_session_data'

Note that setting the primary key to the session_id frees you from having a separate id column if you don't want it. However, you must set session.model.id = session.session_id by hand! A before filter on ApplicationController is a good place.

Since the default class is a simple Active Record, you get timestamps for free if you add created_at and updated_at datetime columns to the sessions table, making periodic session expiration a snap.

You may provide your own session class implementation, whether a feature-packed Active Record or a bare-metal high-performance SQL store, by setting

ActiveRecord::SessionStore.session_class = MySessionClass

You must implement these methods:

self.find_by_session_id(session_id)
initialize(hash_of_session_id_and_data, options_hash = {})
attr_reader :session_id
attr_accessor :data
save
destroy

The example SqlBypass class is a generic SQL session store. You may use it as a basis for high-performance database-specific stores.

Constants

ENV_SESSION_OPTIONS_KEY
SESSION_RECORD_KEY

Private Instance Methods

destroy_session(env, session_id, options) click to toggle source
# File lib/active_record/session_store.rb, line 336
def destroy_session(env, session_id, options)
  if sid = current_session_id(env)
    Base.silence do
      get_session_model(env, sid).destroy
      env[SESSION_RECORD_KEY] = nil
    end
  end

  generate_sid unless options[:drop]
end
find_session(id) click to toggle source
# File lib/active_record/session_store.rb, line 355
def find_session(id)
  @@session_class.find_by_session_id(id) ||
    @@session_class.new(:session_id => id, :data => {})
end
get_session(env, sid) click to toggle source
# File lib/active_record/session_store.rb, line 306
def get_session(env, sid)
  Base.silence do
    unless sid and session = @@session_class.find_by_session_id(sid)
      # If the sid was nil or if there is no pre-existing session under the sid,
      # force the generation of a new sid and associate a new session associated with the new sid
      sid = generate_sid
      session = @@session_class.new(:session_id => sid, :data => {})
    end
    env[SESSION_RECORD_KEY] = session
    [sid, session.data]
  end
end
get_session_model(env, sid) click to toggle source
# File lib/active_record/session_store.rb, line 347
def get_session_model(env, sid)
  if env[ENV_SESSION_OPTIONS_KEY][:id].nil?
    env[SESSION_RECORD_KEY] = find_session(sid)
  else
    env[SESSION_RECORD_KEY] ||= find_session(sid)
  end
end
set_session(env, sid, session_data, options) click to toggle source
# File lib/active_record/session_store.rb, line 319
def set_session(env, sid, session_data, options)
  Base.silence do
    record = get_session_model(env, sid)
    record.data = session_data
    return false unless record.save

    session_data = record.data
    if session_data && session_data.respond_to?(:each_value)
      session_data.each_value do |obj|
        obj.clear_association_cache if obj.respond_to?(:clear_association_cache)
      end
    end
  end

  sid
end