require 'cgi'
require 'cgi/session'
require 'digest/md5'
require 'base64'
class CGI
class Session
# 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
# may be used as the backing store.
#
# The default assumes a +sessions+ tables with columns +id+ (numeric
# primary key), +session_id+ (text), and +data+ (text). Session data is
# marshaled to +data+. +session_id+ should be indexed for speedy lookups.
#
# 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, whether a feature-packed
# Active Record or a bare-metal high-performance SQL store, by setting
# +CGI::Session::ActiveRecordStore.session_class = MySessionClass+
# You must implement these methods:
# self.find_by_session_id(session_id)
# initialize(hash_of_session_id_and_data)
# attr_reader :session_id
# attr_accessor :data
# save!
# destroy
#
# The fast SqlBypass class is a generic SQL session store. You may
# use it as a basis for high-performance database-specific stores.
class ActiveRecordStore
# The default Active Record class.
class Session < ActiveRecord::Base
before_save :marshal_data!
before_update :data_changed?
class << self
# Hook to set up sessid compatibility.
def find_by_session_id(session_id)
setup_sessid_compatibility!
find_by_session_id(session_id)
end
def marshal(data) Base64.encode64(Marshal.dump(data)) end
def unmarshal(data) Marshal.load(Base64.decode64(data)) end
def fingerprint(data) Digest::MD5.hexdigest(data) end
def create_table!
connection.execute <<-end_sql
CREATE TABLE #{table_name} (
id INTEGER PRIMARY KEY,
#{connection.quote_column_name('session_id')} TEXT UNIQUE,
#{connection.quote_column_name('data')} TEXT
)
end_sql
end
def drop_table!
connection.execute "DROP TABLE #{table_name}"
end
private
# Compatibility with tables using sessid instead of session_id.
def setup_sessid_compatibility!
# Reset column info since it may be stale.
reset_column_information
if columns_hash['sessid']
def self.find_by_session_id(*args)
find_by_sessid(*args)
end
define_method(:session_id) { sessid }
define_method(:session_id=) { |session_id| self.sessid = session_id }
else
def self.find_by_session_id(session_id)
find :first, :conditions => ["session_id #{attribute_condition(session_id)}", session_id]
end
end
end
end
# Lazy-unmarshal session state. Take a fingerprint so we can detect
# whether to save changes later.
def data
unless @data
case @data = read_attribute('data')
when String
@fingerprint = self.class.fingerprint(@data)
@data = self.class.unmarshal(@data)
when nil
@data = {}
@fingerprint = nil
end
end
@data
end
private
def marshal_data!
write_attribute('data', self.class.marshal(@data || {}))
end
def data_changed?
old_fingerprint, @fingerprint = @fingerprint, self.class.fingerprint(read_attribute('data'))
old_fingerprint != @fingerprint
end
end
# A barebones session store which duck-types with the default session
# store but bypasses Active Record and issues SQL directly.
#
# The database connection, table name, and session id and data columns
# are configurable class attributes. Marshaling and unmarshaling
# are implemented as class methods that you may override. By default,
# marshaling data is +Base64.encode64(Marshal.dump(data))+ and
# unmarshaling data is +Marshal.load(Base64.decode64(data))+.
#
# This marshaling behavior is intended to store the widest range of
# binary session data in a +text+ column. For higher performance,
# store in a +blob+ column instead and forgo the Base64 encoding.
class SqlBypass
# Use the ActiveRecord::Base.connection by default.
cattr_accessor :connection
def self.connection
@@connection ||= ActiveRecord::Base.connection
end
# The table name defaults to 'sessions'.
cattr_accessor :table_name
@@table_name = 'sessions'
# The session id field defaults to 'session_id'.
cattr_accessor :session_id_column
@@session_id_column = 'session_id'
# The data field defaults to 'data'.
cattr_accessor :data_column
@@data_column = 'data'
class << self
# Look up a session by id and unmarshal its data if found.
def find_by_session_id(session_id)
if record = @@connection.select_one("SELECT * FROM #{@@table_name} WHERE #{@@session_id_column}=#{@@connection.quote(session_id)}")
new(:session_id => session_id, :marshaled_data => record['data'])
end
end
def marshal(data) Base64.encode64(Marshal.dump(data)) end
def unmarshal(data) Marshal.load(Base64.decode64(data)) end
def fingerprint(data) Digest::MD5.hexdigest(data) end
def create_table!
@@connection.execute <<-end_sql
CREATE TABLE #{table_name} (
id INTEGER PRIMARY KEY,
#{@@connection.quote_column_name(session_id_column)} TEXT UNIQUE,
#{@@connection.quote_column_name(data_column)} TEXT
)
end_sql
end
def drop_table!
@@connection.execute "DROP TABLE #{table_name}"
end
end
attr_reader :session_id
attr_writer :data
# Look for normal and marshaled data, self.find_by_session_id's way of
# telling us to postpone unmarshaling until the data is requested.
# We need to handle a normal data attribute in case of a new record.
def initialize(attributes)
@session_id, @data, @marshaled_data = attributes[:session_id], attributes[:data], attributes[:marshaled_data]
@new_record = @marshaled_data.nil?
end
def new_record?
@new_record
end
# Lazy-unmarshal session state. Take a fingerprint so we can detect
# whether to save changes later.
def data
unless @data
if @marshaled_data
@fingerprint = self.class.fingerprint(@marshaled_data)
@data, @marshaled_data = self.class.unmarshal(@marshaled_data), nil
else
@data = {}
@fingerprint = nil
end
end
@data
end
def save!
marshaled_data = self.class.marshal(data)
if @new_record
@new_record = false
@@connection.update <<-end_sql, 'Create session'
INSERT INTO #{@@table_name} (
#{@@connection.quote_column_name(@@session_id_column)},
#{@@connection.quote_column_name(@@data_column)} )
VALUES (
#{@@connection.quote(session_id)},
#{@@connection.quote(marshaled_data)} )
end_sql
else
old_fingerprint, @fingerprint = @fingerprint, self.class.fingerprint(marshaled_data)
if old_fingerprint != @fingerprint
@@connection.update <<-end_sql, 'Update session'
UPDATE #{@@table_name}
SET #{@@connection.quote_column_name(@@data_column)}=#{@@connection.quote(marshaled_data)}
WHERE #{@@connection.quote_column_name(@@session_id_column)}=#{@@connection.quote(session_id)}
end_sql
end
end
end
def destroy
unless @new_record
@@connection.delete <<-end_sql, 'Destroy session'
DELETE FROM #{@@table_name}
WHERE #{@@connection.quote_column_name(@@session_id_column)}=#{@@connection.quote(session_id)}
end_sql
end
end
end
# The class used for session storage. Defaults to
# CGI::Session::ActiveRecordStore::Session.
cattr_accessor :session_class
@@session_class = Session
# Find or instantiate a session given a CGI::Session.
def initialize(session, option = nil)
session_id = session.session_id
unless @session = @@session_class.find_by_session_id(session_id)
unless session.new_session
raise CGI::Session::NoSession, 'uninitialized session'
end
@session = @@session_class.new(:session_id => session_id, :data => {})
end
end
# Restore session state. The session model handles unmarshaling.
def restore
if @session
@session.data
end
end
# Save session store.
def update
if @session
ActiveRecord::Base.silence { @session.save! }
end
end
# Save and close the session store.
def close
if @session
update
@session = nil
end
end
# Delete and close the session store.
def delete
if @session
ActiveRecord::Base.silence { @session.destroy }
@session = nil
end
end
end
end
end