Chris@0: # Copyright (c) 2005 Rick Olson
Chris@0: # 
Chris@0: # Permission is hereby granted, free of charge, to any person obtaining
Chris@0: # a copy of this software and associated documentation files (the
Chris@0: # "Software"), to deal in the Software without restriction, including
Chris@0: # without limitation the rights to use, copy, modify, merge, publish,
Chris@0: # distribute, sublicense, and/or sell copies of the Software, and to
Chris@0: # permit persons to whom the Software is furnished to do so, subject to
Chris@0: # the following conditions:
Chris@0: # 
Chris@0: # The above copyright notice and this permission notice shall be
Chris@0: # included in all copies or substantial portions of the Software.
Chris@0: # 
Chris@0: # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
Chris@0: # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
Chris@0: # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
Chris@0: # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
Chris@0: # LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
Chris@0: # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
Chris@0: # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Chris@0: 
Chris@0: module ActiveRecord #:nodoc:
Chris@0:   module Acts #:nodoc:
Chris@0:     # Specify this act if you want to save a copy of the row in a versioned table.  This assumes there is a 
Chris@0:     # versioned table ready and that your model has a version field.  This works with optimistic locking if the lock_version
Chris@0:     # column is present as well.
Chris@0:     #
Chris@0:     # The class for the versioned model is derived the first time it is seen. Therefore, if you change your database schema you have to restart
Chris@0:     # your container for the changes to be reflected. In development mode this usually means restarting WEBrick.
Chris@0:     #
Chris@0:     #   class Page < ActiveRecord::Base
Chris@0:     #     # assumes pages_versions table
Chris@0:     #     acts_as_versioned
Chris@0:     #   end
Chris@0:     #
Chris@0:     # Example:
Chris@0:     #
Chris@0:     #   page = Page.create(:title => 'hello world!')
Chris@0:     #   page.version       # => 1
Chris@0:     #
Chris@0:     #   page.title = 'hello world'
Chris@0:     #   page.save
Chris@0:     #   page.version       # => 2
Chris@0:     #   page.versions.size # => 2
Chris@0:     #
Chris@0:     #   page.revert_to(1)  # using version number
Chris@0:     #   page.title         # => 'hello world!'
Chris@0:     #
Chris@0:     #   page.revert_to(page.versions.last) # using versioned instance
Chris@0:     #   page.title         # => 'hello world'
Chris@0:     #
Chris@0:     #   page.versions.earliest # efficient query to find the first version
Chris@0:     #   page.versions.latest   # efficient query to find the most recently created version
Chris@0:     #
Chris@0:     #
Chris@0:     # Simple Queries to page between versions
Chris@0:     #
Chris@0:     #   page.versions.before(version) 
Chris@0:     #   page.versions.after(version)
Chris@0:     #
Chris@0:     # Access the previous/next versions from the versioned model itself
Chris@0:     #
Chris@0:     #   version = page.versions.latest
Chris@0:     #   version.previous # go back one version
Chris@0:     #   version.next     # go forward one version
Chris@0:     #
Chris@0:     # See ActiveRecord::Acts::Versioned::ClassMethods#acts_as_versioned for configuration options
Chris@0:     module Versioned
Chris@0:       CALLBACKS = [:set_new_version, :save_version_on_create, :save_version?, :clear_altered_attributes]
Chris@0:       def self.included(base) # :nodoc:
Chris@0:         base.extend ClassMethods
Chris@0:       end
Chris@0: 
Chris@0:       module ClassMethods
Chris@0:         # == Configuration options
Chris@0:         #
Chris@0:         # * <tt>class_name</tt> - versioned model class name (default: PageVersion in the above example)
Chris@0:         # * <tt>table_name</tt> - versioned model table name (default: page_versions in the above example)
Chris@0:         # * <tt>foreign_key</tt> - foreign key used to relate the versioned model to the original model (default: page_id in the above example)
Chris@0:         # * <tt>inheritance_column</tt> - name of the column to save the model's inheritance_column value for STI.  (default: versioned_type)
Chris@0:         # * <tt>version_column</tt> - name of the column in the model that keeps the version number (default: version)
Chris@0:         # * <tt>sequence_name</tt> - name of the custom sequence to be used by the versioned model.
Chris@0:         # * <tt>limit</tt> - number of revisions to keep, defaults to unlimited
Chris@0:         # * <tt>if</tt> - symbol of method to check before saving a new version.  If this method returns false, a new version is not saved.
Chris@0:         #   For finer control, pass either a Proc or modify Model#version_condition_met?
Chris@0:         #
Chris@0:         #     acts_as_versioned :if => Proc.new { |auction| !auction.expired? }
Chris@0:         #
Chris@0:         #   or...
Chris@0:         #
Chris@0:         #     class Auction
Chris@0:         #       def version_condition_met? # totally bypasses the <tt>:if</tt> option
Chris@0:         #         !expired?
Chris@0:         #       end
Chris@0:         #     end
Chris@0:         #
Chris@0:         # * <tt>if_changed</tt> - Simple way of specifying attributes that are required to be changed before saving a model.  This takes
Chris@0:         #   either a symbol or array of symbols.  WARNING - This will attempt to overwrite any attribute setters you may have.
Chris@0:         #   Use this instead if you want to write your own attribute setters (and ignore if_changed):
Chris@0:         # 
Chris@0:         #     def name=(new_name)
Chris@0:         #       write_changed_attribute :name, new_name
Chris@0:         #     end
Chris@0:         #
Chris@0:         # * <tt>extend</tt> - Lets you specify a module to be mixed in both the original and versioned models.  You can also just pass a block
Chris@0:         #   to create an anonymous mixin:
Chris@0:         #
Chris@0:         #     class Auction
Chris@0:         #       acts_as_versioned do
Chris@0:         #         def started?
Chris@0:         #           !started_at.nil?
Chris@0:         #         end
Chris@0:         #       end
Chris@0:         #     end
Chris@0:         #
Chris@0:         #   or...
Chris@0:         #
Chris@0:         #     module AuctionExtension
Chris@0:         #       def started?
Chris@0:         #         !started_at.nil?
Chris@0:         #       end
Chris@0:         #     end
Chris@0:         #     class Auction
Chris@0:         #       acts_as_versioned :extend => AuctionExtension
Chris@0:         #     end
Chris@0:         #
Chris@0:         #  Example code:
Chris@0:         #
Chris@0:         #    @auction = Auction.find(1)
Chris@0:         #    @auction.started?
Chris@0:         #    @auction.versions.first.started?
Chris@0:         #
Chris@0:         # == Database Schema
Chris@0:         #
Chris@0:         # The model that you're versioning needs to have a 'version' attribute. The model is versioned 
Chris@0:         # into a table called #{model}_versions where the model name is singlular. The _versions table should 
Chris@0:         # contain all the fields you want versioned, the same version column, and a #{model}_id foreign key field.
Chris@0:         #
Chris@0:         # A lock_version field is also accepted if your model uses Optimistic Locking.  If your table uses Single Table inheritance,
Chris@0:         # then that field is reflected in the versioned model as 'versioned_type' by default.
Chris@0:         #
Chris@0:         # Acts_as_versioned comes prepared with the ActiveRecord::Acts::Versioned::ActMethods::ClassMethods#create_versioned_table 
Chris@0:         # method, perfect for a migration.  It will also create the version column if the main model does not already have it.
Chris@0:         #
Chris@0:         #   class AddVersions < ActiveRecord::Migration
Chris@0:         #     def self.up
Chris@0:         #       # create_versioned_table takes the same options hash
Chris@0:         #       # that create_table does
Chris@0:         #       Post.create_versioned_table
Chris@0:         #     end
Chris@0:         # 
Chris@0:         #     def self.down
Chris@0:         #       Post.drop_versioned_table
Chris@0:         #     end
Chris@0:         #   end
Chris@0:         # 
Chris@0:         # == Changing What Fields Are Versioned
Chris@0:         #
Chris@0:         # By default, acts_as_versioned will version all but these fields: 
Chris@0:         # 
Chris@0:         #   [self.primary_key, inheritance_column, 'version', 'lock_version', versioned_inheritance_column]
Chris@0:         #
Chris@0:         # You can add or change those by modifying #non_versioned_columns.  Note that this takes strings and not symbols.
Chris@0:         #
Chris@0:         #   class Post < ActiveRecord::Base
Chris@0:         #     acts_as_versioned
Chris@0:         #     self.non_versioned_columns << 'comments_count'
Chris@0:         #   end
Chris@0:         # 
Chris@0:         def acts_as_versioned(options = {}, &extension)
Chris@0:           # don't allow multiple calls
Chris@0:           return if self.included_modules.include?(ActiveRecord::Acts::Versioned::ActMethods)
Chris@0: 
Chris@0:           send :include, ActiveRecord::Acts::Versioned::ActMethods
Chris@0: 
Chris@0:           cattr_accessor :versioned_class_name, :versioned_foreign_key, :versioned_table_name, :versioned_inheritance_column, 
Chris@0:             :version_column, :max_version_limit, :track_altered_attributes, :version_condition, :version_sequence_name, :non_versioned_columns,
Chris@0:             :version_association_options
Chris@0: 
Chris@0:           # legacy
Chris@0:           alias_method :non_versioned_fields,  :non_versioned_columns
Chris@0:           alias_method :non_versioned_fields=, :non_versioned_columns=
Chris@0: 
Chris@0:           class << self
Chris@0:             alias_method :non_versioned_fields,  :non_versioned_columns
Chris@0:             alias_method :non_versioned_fields=, :non_versioned_columns=
Chris@0:           end
Chris@0: 
Chris@0:           send :attr_accessor, :altered_attributes
Chris@0: 
Chris@0:           self.versioned_class_name         = options[:class_name]  || "Version"
Chris@0:           self.versioned_foreign_key        = options[:foreign_key] || self.to_s.foreign_key
Chris@0:           self.versioned_table_name         = options[:table_name]  || "#{table_name_prefix}#{base_class.name.demodulize.underscore}_versions#{table_name_suffix}"
Chris@0:           self.versioned_inheritance_column = options[:inheritance_column] || "versioned_#{inheritance_column}"
Chris@0:           self.version_column               = options[:version_column]     || 'version'
Chris@0:           self.version_sequence_name        = options[:sequence_name]
Chris@0:           self.max_version_limit            = options[:limit].to_i
Chris@0:           self.version_condition            = options[:if] || true
Chris@0:           self.non_versioned_columns        = [self.primary_key, inheritance_column, 'version', 'lock_version', versioned_inheritance_column]
Chris@0:           self.version_association_options  = {
Chris@0:                                                 :class_name  => "#{self.to_s}::#{versioned_class_name}",
Chris@0:                                                 :foreign_key => versioned_foreign_key,
Chris@0:                                                 :dependent   => :delete_all
Chris@0:                                               }.merge(options[:association_options] || {})
Chris@0: 
Chris@0:           if block_given?
Chris@0:             extension_module_name = "#{versioned_class_name}Extension"
Chris@0:             silence_warnings do
Chris@0:               self.const_set(extension_module_name, Module.new(&extension))
Chris@0:             end
Chris@0: 
Chris@0:             options[:extend] = self.const_get(extension_module_name)
Chris@0:           end
Chris@0: 
Chris@0:           class_eval do
Chris@0:             has_many :versions, version_association_options do
Chris@0:               # finds earliest version of this record
Chris@0:               def earliest
Chris@0:                 @earliest ||= find(:first, :order => 'version')
Chris@0:               end
Chris@0: 
Chris@0:               # find latest version of this record
Chris@0:               def latest
Chris@0:                 @latest ||= find(:first, :order => 'version desc')
Chris@0:               end
Chris@0:             end
Chris@0:             before_save  :set_new_version
Chris@0:             after_create :save_version_on_create
Chris@0:             after_update :save_version
Chris@0:             after_save   :clear_old_versions
Chris@0:             after_save   :clear_altered_attributes
Chris@0: 
Chris@0:             unless options[:if_changed].nil?
Chris@0:               self.track_altered_attributes = true
Chris@0:               options[:if_changed] = [options[:if_changed]] unless options[:if_changed].is_a?(Array)
Chris@0:               options[:if_changed].each do |attr_name|
Chris@0:                 define_method("#{attr_name}=") do |value|
Chris@0:                   write_changed_attribute attr_name, value
Chris@0:                 end
Chris@0:               end
Chris@0:             end
Chris@0: 
Chris@0:             include options[:extend] if options[:extend].is_a?(Module)
Chris@0:           end
Chris@0: 
Chris@0:           # create the dynamic versioned model
Chris@0:           const_set(versioned_class_name, Class.new(ActiveRecord::Base)).class_eval do
Chris@0:             def self.reloadable? ; false ; end
Chris@0:             # find first version before the given version
Chris@0:             def self.before(version)
Chris@0:               find :first, :order => 'version desc',
Chris@0:                 :conditions => ["#{original_class.versioned_foreign_key} = ? and version < ?", version.send(original_class.versioned_foreign_key), version.version]
Chris@0:             end
Chris@0: 
Chris@0:             # find first version after the given version.
Chris@0:             def self.after(version)
Chris@0:               find :first, :order => 'version',
Chris@0:                 :conditions => ["#{original_class.versioned_foreign_key} = ? and version > ?", version.send(original_class.versioned_foreign_key), version.version]
Chris@0:             end
Chris@0: 
Chris@0:             def previous
Chris@0:               self.class.before(self)
Chris@0:             end
Chris@0: 
Chris@0:             def next
Chris@0:               self.class.after(self)
Chris@0:             end
Chris@0: 
Chris@0:             def versions_count
Chris@0:               page.version
Chris@0:             end
Chris@0:           end
Chris@0: 
Chris@0:           versioned_class.cattr_accessor :original_class
Chris@0:           versioned_class.original_class = self
Chris@0:           versioned_class.set_table_name versioned_table_name
Chris@0:           versioned_class.belongs_to self.to_s.demodulize.underscore.to_sym, 
Chris@0:             :class_name  => "::#{self.to_s}", 
Chris@0:             :foreign_key => versioned_foreign_key
Chris@0:           versioned_class.send :include, options[:extend]         if options[:extend].is_a?(Module)
Chris@0:           versioned_class.set_sequence_name version_sequence_name if version_sequence_name
Chris@0:         end
Chris@0:       end
Chris@0: 
Chris@0:       module ActMethods
Chris@0:         def self.included(base) # :nodoc:
Chris@0:           base.extend ClassMethods
Chris@0:         end
Chris@0: 
Chris@0:         # Finds a specific version of this record
Chris@0:         def find_version(version = nil)
Chris@0:           self.class.find_version(id, version)
Chris@0:         end
Chris@0: 
Chris@0:         # Saves a version of the model if applicable
Chris@0:         def save_version
Chris@0:           save_version_on_create if save_version?
Chris@0:         end
Chris@0: 
Chris@0:         # Saves a version of the model in the versioned table.  This is called in the after_save callback by default
Chris@0:         def save_version_on_create
Chris@0:           rev = self.class.versioned_class.new
Chris@0:           self.clone_versioned_model(self, rev)
Chris@0:           rev.version = send(self.class.version_column)
Chris@0:           rev.send("#{self.class.versioned_foreign_key}=", self.id)
Chris@0:           rev.save
Chris@0:         end
Chris@0: 
Chris@0:         # Clears old revisions if a limit is set with the :limit option in <tt>acts_as_versioned</tt>.
Chris@0:         # Override this method to set your own criteria for clearing old versions.
Chris@0:         def clear_old_versions
Chris@0:           return if self.class.max_version_limit == 0
Chris@0:           excess_baggage = send(self.class.version_column).to_i - self.class.max_version_limit
Chris@0:           if excess_baggage > 0
Chris@0:             sql = "DELETE FROM #{self.class.versioned_table_name} WHERE version <= #{excess_baggage} AND #{self.class.versioned_foreign_key} = #{self.id}"
Chris@0:             self.class.versioned_class.connection.execute sql
Chris@0:           end
Chris@0:         end
Chris@0: 
Chris@0:         def versions_count
Chris@0:           version
Chris@0:         end
Chris@0: 
Chris@0:         # Reverts a model to a given version.  Takes either a version number or an instance of the versioned model
Chris@0:         def revert_to(version)
Chris@0:           if version.is_a?(self.class.versioned_class)
Chris@0:             return false unless version.send(self.class.versioned_foreign_key) == self.id and !version.new_record?
Chris@0:           else
Chris@0:             return false unless version = versions.find_by_version(version)
Chris@0:           end
Chris@0:           self.clone_versioned_model(version, self)
Chris@0:           self.send("#{self.class.version_column}=", version.version)
Chris@0:           true
Chris@0:         end
Chris@0: 
Chris@0:         # Reverts a model to a given version and saves the model.
Chris@0:         # Takes either a version number or an instance of the versioned model
Chris@0:         def revert_to!(version)
Chris@0:           revert_to(version) ? save_without_revision : false
Chris@0:         end
Chris@0: 
Chris@0:         # Temporarily turns off Optimistic Locking while saving.  Used when reverting so that a new version is not created.
Chris@0:         def save_without_revision
Chris@0:           save_without_revision!
Chris@0:           true
Chris@0:         rescue
Chris@0:           false
Chris@0:         end
Chris@0: 
Chris@0:         def save_without_revision!
Chris@0:           without_locking do
Chris@0:             without_revision do
Chris@0:               save!
Chris@0:             end
Chris@0:           end
Chris@0:         end
Chris@0: 
Chris@0:         # Returns an array of attribute keys that are versioned.  See non_versioned_columns
Chris@0:         def versioned_attributes
Chris@0:           self.attributes.keys.select { |k| !self.class.non_versioned_columns.include?(k) }
Chris@0:         end
Chris@0: 
Chris@0:         # If called with no parameters, gets whether the current model has changed and needs to be versioned.
Chris@0:         # If called with a single parameter, gets whether the parameter has changed.
Chris@0:         def changed?(attr_name = nil)
Chris@0:           attr_name.nil? ?
Chris@0:             (!self.class.track_altered_attributes || (altered_attributes && altered_attributes.length > 0)) :
Chris@0:             (altered_attributes && altered_attributes.include?(attr_name.to_s))
Chris@0:         end
Chris@0: 
Chris@0:         # keep old dirty? method
Chris@0:         alias_method :dirty?, :changed?
Chris@0: 
Chris@0:         # Clones a model.  Used when saving a new version or reverting a model's version.
Chris@0:         def clone_versioned_model(orig_model, new_model)
Chris@0:           self.versioned_attributes.each do |key|
Chris@0:             new_model.send("#{key}=", orig_model.send(key)) if orig_model.has_attribute?(key)
Chris@0:           end
Chris@0: 
Chris@0:           if orig_model.is_a?(self.class.versioned_class)
Chris@0:             new_model[new_model.class.inheritance_column] = orig_model[self.class.versioned_inheritance_column]
Chris@0:           elsif new_model.is_a?(self.class.versioned_class)
Chris@0:             new_model[self.class.versioned_inheritance_column] = orig_model[orig_model.class.inheritance_column]
Chris@0:           end
Chris@0:         end
Chris@0: 
Chris@0:         # Checks whether a new version shall be saved or not.  Calls <tt>version_condition_met?</tt> and <tt>changed?</tt>.
Chris@0:         def save_version?
Chris@0:           version_condition_met? && changed?
Chris@0:         end
Chris@0: 
Chris@0:         # Checks condition set in the :if option to check whether a revision should be created or not.  Override this for
Chris@0:         # custom version condition checking.
Chris@0:         def version_condition_met?
Chris@0:           case
Chris@0:           when version_condition.is_a?(Symbol)
Chris@0:             send(version_condition)
Chris@0:           when version_condition.respond_to?(:call) && (version_condition.arity == 1 || version_condition.arity == -1)
Chris@0:             version_condition.call(self)
Chris@0:           else
Chris@0:             version_condition
Chris@0:           end
Chris@0:         end
Chris@0: 
Chris@0:         # Executes the block with the versioning callbacks disabled.
Chris@0:         #
Chris@0:         #   @foo.without_revision do
Chris@0:         #     @foo.save
Chris@0:         #   end
Chris@0:         #
Chris@0:         def without_revision(&block)
Chris@0:           self.class.without_revision(&block)
Chris@0:         end
Chris@0: 
Chris@0:         # Turns off optimistic locking for the duration of the block
Chris@0:         #
Chris@0:         #   @foo.without_locking do
Chris@0:         #     @foo.save
Chris@0:         #   end
Chris@0:         #
Chris@0:         def without_locking(&block)
Chris@0:           self.class.without_locking(&block)
Chris@0:         end
Chris@0: 
Chris@0:         def empty_callback() end #:nodoc:
Chris@0: 
Chris@0:         protected
Chris@0:           # sets the new version before saving, unless you're using optimistic locking.  In that case, let it take care of the version.
Chris@0:           def set_new_version
Chris@0:             self.send("#{self.class.version_column}=", self.next_version) if new_record? || (!locking_enabled? && save_version?)
Chris@0:           end
Chris@0: 
Chris@0:           # Gets the next available version for the current record, or 1 for a new record
Chris@0:           def next_version
Chris@0:             return 1 if new_record?
Chris@0:             (versions.calculate(:max, :version) || 0) + 1
Chris@0:           end
Chris@0: 
Chris@0:           # clears current changed attributes.  Called after save.
Chris@0:           def clear_altered_attributes
Chris@0:             self.altered_attributes = []
Chris@0:           end
Chris@0: 
Chris@0:           def write_changed_attribute(attr_name, attr_value)
Chris@0:             # Convert to db type for comparison. Avoids failing Float<=>String comparisons.
Chris@0:             attr_value_for_db = self.class.columns_hash[attr_name.to_s].type_cast(attr_value)
Chris@0:             (self.altered_attributes ||= []) << attr_name.to_s unless self.changed?(attr_name) || self.send(attr_name) == attr_value_for_db
Chris@0:             write_attribute(attr_name, attr_value_for_db)
Chris@0:           end
Chris@0: 
Chris@0:         module ClassMethods
Chris@0:           # Finds a specific version of a specific row of this model
Chris@0:           def find_version(id, version = nil)
Chris@0:             return find(id) unless version
Chris@0: 
Chris@0:             conditions = ["#{versioned_foreign_key} = ? AND version = ?", id, version]
Chris@0:             options = { :conditions => conditions, :limit => 1 }
Chris@0: 
Chris@0:             if result = find_versions(id, options).first
Chris@0:               result
Chris@0:             else
Chris@0:               raise RecordNotFound, "Couldn't find #{name} with ID=#{id} and VERSION=#{version}"
Chris@0:             end
Chris@0:           end
Chris@0: 
Chris@0:           # Finds versions of a specific model.  Takes an options hash like <tt>find</tt>
Chris@0:           def find_versions(id, options = {})
Chris@0:             versioned_class.find :all, {
Chris@0:               :conditions => ["#{versioned_foreign_key} = ?", id],
Chris@0:               :order      => 'version' }.merge(options)
Chris@0:           end
Chris@0: 
Chris@0:           # Returns an array of columns that are versioned.  See non_versioned_columns
Chris@0:           def versioned_columns
Chris@0:             self.columns.select { |c| !non_versioned_columns.include?(c.name) }
Chris@0:           end
Chris@0: 
Chris@0:           # Returns an instance of the dynamic versioned model
Chris@0:           def versioned_class
Chris@0:             const_get versioned_class_name
Chris@0:           end
Chris@0: 
Chris@0:           # Rake migration task to create the versioned table using options passed to acts_as_versioned
Chris@0:           def create_versioned_table(create_table_options = {})
Chris@0:             # create version column in main table if it does not exist
Chris@0:             if !self.content_columns.find { |c| %w(version lock_version).include? c.name }
Chris@0:               self.connection.add_column table_name, :version, :integer
Chris@0:             end
Chris@0: 
Chris@0:             self.connection.create_table(versioned_table_name, create_table_options) do |t|
Chris@0:               t.column versioned_foreign_key, :integer
Chris@0:               t.column :version, :integer
Chris@0:             end
Chris@0: 
Chris@0:             updated_col = nil
Chris@0:             self.versioned_columns.each do |col| 
Chris@0:               updated_col = col if !updated_col && %(updated_at updated_on).include?(col.name)
Chris@0:               self.connection.add_column versioned_table_name, col.name, col.type, 
Chris@0:                 :limit => col.limit, 
Chris@0:                 :default => col.default,
Chris@0:                 :scale => col.scale,
Chris@0:                 :precision => col.precision
Chris@0:             end
Chris@0: 
Chris@0:             if type_col = self.columns_hash[inheritance_column]
Chris@0:               self.connection.add_column versioned_table_name, versioned_inheritance_column, type_col.type, 
Chris@0:                 :limit => type_col.limit, 
Chris@0:                 :default => type_col.default,
Chris@0:                 :scale => type_col.scale,
Chris@0:                 :precision => type_col.precision
Chris@0:             end
Chris@0: 
Chris@0:             if updated_col.nil?
Chris@0:               self.connection.add_column versioned_table_name, :updated_at, :timestamp
Chris@0:             end
Chris@0:           end
Chris@0: 
Chris@0:           # Rake migration task to drop the versioned table
Chris@0:           def drop_versioned_table
Chris@0:             self.connection.drop_table versioned_table_name
Chris@0:           end
Chris@0: 
Chris@0:           # Executes the block with the versioning callbacks disabled.
Chris@0:           #
Chris@0:           #   Foo.without_revision do
Chris@0:           #     @foo.save
Chris@0:           #   end
Chris@0:           #
Chris@0:           def without_revision(&block)
Chris@0:             class_eval do 
Chris@0:               CALLBACKS.each do |attr_name|
Chris@0:                 alias_method "orig_#{attr_name}".to_sym, attr_name
Chris@0:                 alias_method attr_name, :empty_callback
Chris@0:               end
Chris@0:             end
Chris@0:             block.call
Chris@0:           ensure
Chris@0:             class_eval do 
Chris@0:               CALLBACKS.each do |attr_name|
Chris@0:                 alias_method attr_name, "orig_#{attr_name}".to_sym
Chris@0:               end
Chris@0:             end
Chris@0:           end
Chris@0: 
Chris@0:           # Turns off optimistic locking for the duration of the block
Chris@0:           #
Chris@0:           #   Foo.without_locking do
Chris@0:           #     @foo.save
Chris@0:           #   end
Chris@0:           #
Chris@0:           def without_locking(&block)
Chris@0:             current = ActiveRecord::Base.lock_optimistically
Chris@0:             ActiveRecord::Base.lock_optimistically = false if current
Chris@0:             result = block.call
Chris@0:             ActiveRecord::Base.lock_optimistically = true if current
Chris@0:             result
Chris@0:           end
Chris@0:         end
Chris@0:       end
Chris@0:     end
Chris@0:   end
Chris@0: end
Chris@0: 
Chris@0: ActiveRecord::Base.send :include, ActiveRecord::Acts::Versioned