denis · January 14, 2010 15:11 · Jan 14, 2010 · Jan 14, 2010
diff --git a/gistfile1.txt → gistfile1.rb b/gistfile1.txt → gistfile1.rb
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,490 @@
+# Copyright (c) 2005 Rick Olson
+# 
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+# 
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+module ActiveRecord #:nodoc:
+  module Acts #:nodoc:
+    # Specify this act if you want to save a copy of the row in a versioned table.  This assumes there is a 
+    # versioned table ready and that your model has a version field.  This works with optimistic locking if the lock_version
+    # column is present as well.
+    #
+    # 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
+    # your container for the changes to be reflected. In development mode this usually means restarting WEBrick.
+    #
+    #   class Page < ActiveRecord::Base
+    #     # assumes pages_versions table
+    #     acts_as_versioned
+    #   end
+    #
+    # Example:
+    #
+    #   page = Page.create(:title => 'hello world!')
+    #   page.version       # => 1
+    #
+    #   page.title = 'hello world'
+    #   page.save
+    #   page.version       # => 2
+    #   page.versions.size # => 2
+    #
+    #   page.revert_to(1)  # using version number
+    #   page.title         # => 'hello world!'
+    #
+    #   page.revert_to(page.versions.last) # using versioned instance
+    #   page.title         # => 'hello world'
+    #
+    #   page.versions.earliest # efficient query to find the first version
+    #   page.versions.latest   # efficient query to find the most recently created version
+    #
+    #
+    # Simple Queries to page between versions
+    #
+    #   page.versions.before(version) 
+    #   page.versions.after(version)
+    #
+    # Access the previous/next versions from the versioned model itself
+    #
+    #   version = page.versions.latest
+    #   version.previous # go back one version
+    #   version.next     # go forward one version
+    #
+    # See ActiveRecord::Acts::Versioned::ClassMethods#acts_as_versioned for configuration options
+    module Versioned
+      CALLBACKS = [:set_new_version, :save_version, :save_version?]
+      def self.included(base) # :nodoc:
+        base.extend ClassMethods
+      end
+
+      module ClassMethods
+        # == Configuration options
+        #
+        # * <tt>class_name</tt> - versioned model class name (default: PageVersion in the above example)
+        # * <tt>table_name</tt> - versioned model table name (default: page_versions in the above example)
+        # * <tt>foreign_key</tt> - foreign key used to relate the versioned model to the original model (default: page_id in the above example)
+        # * <tt>inheritance_column</tt> - name of the column to save the model's inheritance_column value for STI.  (default: versioned_type)
+        # * <tt>version_column</tt> - name of the column in the model that keeps the version number (default: version)
+        # * <tt>sequence_name</tt> - name of the custom sequence to be used by the versioned model.
+        # * <tt>limit</tt> - number of revisions to keep, defaults to unlimited
+        # * <tt>if</tt> - symbol of method to check before saving a new version.  If this method returns false, a new version is not saved.
+        #   For finer control, pass either a Proc or modify Model#version_condition_met?
+        #
+        #     acts_as_versioned :if => Proc.new { |auction| !auction.expired? }
+        #
+        #   or...
+        #
+        #     class Auction
+        #       def version_condition_met? # totally bypasses the <tt>:if</tt> option
+        #         !expired?
+        #       end
+        #     end
+        #
+        # * <tt>if_changed</tt> - Simple way of specifying attributes that are required to be changed before saving a model.  This takes
+        #   either a symbol or array of symbols.
+        #
+        # * <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
+        #   to create an anonymous mixin:
+        #
+        #     class Auction
+        #       acts_as_versioned do
+        #         def started?
+        #           !started_at.nil?
+        #         end
+        #       end
+        #     end
+        #
+        #   or...
+        #
+        #     module AuctionExtension
+        #       def started?
+        #         !started_at.nil?
+        #       end
+        #     end
+        #     class Auction
+        #       acts_as_versioned :extend => AuctionExtension
+        #     end
+        #
+        #  Example code:
+        #
+        #    @auction = Auction.find(1)
+        #    @auction.started?
+        #    @auction.versions.first.started?
+        #
+        # == Database Schema
+        #
+        # The model that you're versioning needs to have a 'version' attribute. The model is versioned 
+        # into a table called #{model}_versions where the model name is singlular. The _versions table should 
+        # contain all the fields you want versioned, the same version column, and a #{model}_id foreign key field.
+        #
+        # A lock_version field is also accepted if your model uses Optimistic Locking.  If your table uses Single Table inheritance,
+        # then that field is reflected in the versioned model as 'versioned_type' by default.
+        #
+        # Acts_as_versioned comes prepared with the ActiveRecord::Acts::Versioned::ActMethods::ClassMethods#create_versioned_table 
+        # method, perfect for a migration.  It will also create the version column if the main model does not already have it.
+        #
+        #   class AddVersions < ActiveRecord::Migration
+        #     def self.up
+        #       # create_versioned_table takes the same options hash
+        #       # that create_table does
+        #       Post.create_versioned_table
+        #     end
+        # 
+        #     def self.down
+        #       Post.drop_versioned_table
+        #     end
+        #   end
+        # 
+        # == Changing What Fields Are Versioned
+        #
+        # By default, acts_as_versioned will version all but these fields: 
+        # 
+        #   [self.primary_key, inheritance_column, 'version', 'lock_version', versioned_inheritance_column]
+        #
+        # You can add or change those by modifying #non_versioned_columns.  Note that this takes strings and not symbols.
+        #
+        #   class Post < ActiveRecord::Base
+        #     acts_as_versioned
+        #     self.non_versioned_columns << 'comments_count'
+        #   end
+        # 
+        def acts_as_versioned(options = {}, &extension)
+          # don't allow multiple calls
+          return if self.included_modules.include?(ActiveRecord::Acts::Versioned::ActMethods)
+
+          send :include, ActiveRecord::Acts::Versioned::ActMethods
+
+          cattr_accessor :versioned_class_name, :versioned_foreign_key, :versioned_table_name, :versioned_inheritance_column, 
+            :version_column, :max_version_limit, :track_altered_attributes, :version_condition, :version_sequence_name, 
+            :non_versioned_columns, :non_alone_versioned_columns, :version_association_options, :version_if_changed
+
+          self.versioned_class_name         = options[:class_name]  || "Version"
+          self.versioned_foreign_key        = options[:foreign_key] || self.to_s.foreign_key
+          self.versioned_table_name         = options[:table_name]  || "#{table_name_prefix}#{base_class.name.demodulize.underscore}_versions#{table_name_suffix}"
+          self.versioned_inheritance_column = options[:inheritance_column] || "versioned_#{inheritance_column}"
+          self.version_column               = options[:version_column]     || 'version'
+          self.version_sequence_name        = options[:sequence_name]
+          self.max_version_limit            = options[:limit].to_i
+          self.version_condition            = options[:if] || true
+          self.non_versioned_columns        = [self.primary_key, inheritance_column, self.version_column, 'lock_version', versioned_inheritance_column] + options[:non_versioned_columns].to_a.map(&:to_s)
+          self.non_alone_versioned_columns  = [options[:non_alone_versioned_columns]].to_a.map(&:to_s)
+          self.version_association_options  = {
+                                                :class_name  => "#{self.to_s}::#{versioned_class_name}",
+                                                :foreign_key => versioned_foreign_key,
+                                                :dependent   => :delete_all
+                                              }.merge(options[:association_options] || {})
+
+          if block_given?
+            extension_module_name = "#{versioned_class_name}Extension"
+            silence_warnings do
+              self.const_set(extension_module_name, Module.new(&extension))
+            end
+
+            options[:extend] = self.const_get(extension_module_name)
+          end
+
+          class_eval <<-CLASS_METHODS
+            has_many :versions, version_association_options do
+              # finds earliest version of this record
+              def earliest
+                @earliest ||= find(:first, :order => '#{version_column}')
+              end
+
+              # find latest version of this record
+              def latest
+                @latest ||= find(:first, :order => '#{version_column} desc')
+              end
+            end
+            before_save  :set_new_version
+            after_save   :save_version
+            after_save   :clear_old_versions
+
+            unless options[:if_changed].nil?
+              self.track_altered_attributes = true
+              options[:if_changed] = [options[:if_changed]] unless options[:if_changed].is_a?(Array)
+              self.version_if_changed = options[:if_changed].map(&:to_s)
+            end
+
+            include options[:extend] if options[:extend].is_a?(Module)
+          CLASS_METHODS
+
+          # create the dynamic versioned model
+          const_set(versioned_class_name, Class.new(ActiveRecord::Base)).class_eval do
+            def self.reloadable? ; false ; end
+            # find first version before the given version
+            def self.before(version)
+              find :first, :order => 'version desc',
+                :conditions => ["#{original_class.versioned_foreign_key} = ? and version < ?", version.send(original_class.versioned_foreign_key), version.version]
+            end
+
+            # find first version after the given version.
+            def self.after(version)
+              find :first, :order => 'version',
+                :conditions => ["#{original_class.versioned_foreign_key} = ? and version > ?", version.send(original_class.versioned_foreign_key), version.version]
+            end
+
+            def previous
+              self.class.before(self)
+            end
+
+            def next
+              self.class.after(self)
+            end
+
+            def versions_count
+              page.version
+            end
+          end
+
+          versioned_class.cattr_accessor :original_class
+          versioned_class.original_class = self
+          versioned_class.set_table_name versioned_table_name
+          versioned_class.belongs_to self.to_s.demodulize.underscore.to_sym, 
+            :class_name  => "::#{self.to_s}", 
+            :foreign_key => versioned_foreign_key
+          versioned_class.send :include, options[:extend]         if options[:extend].is_a?(Module)
+          versioned_class.set_sequence_name version_sequence_name if version_sequence_name
+        end
+      end
+
+      module ActMethods
+        def self.included(base) # :nodoc:
+          base.extend ClassMethods
+        end
+
+        # Saves a version of the model in the versioned table.  This is called in the after_save callback by default
+        def save_version
+          if @saving_version
+            @saving_version = nil
+            rev = self.class.versioned_class.new
+            clone_versioned_model(self, rev)
+            rev.send("#{self.class.version_column}=", send(self.class.version_column))
+            rev.send("#{self.class.versioned_foreign_key}=", id)
+            rev.save
+          end
+        end
+
+        # Clears old revisions if a limit is set with the :limit option in <tt>acts_as_versioned</tt>.
+        # Override this method to set your own criteria for clearing old versions.
+        def clear_old_versions
+          return if self.class.max_version_limit == 0
+          excess_baggage = send(self.class.version_column).to_i - self.class.max_version_limit
+          if excess_baggage > 0
+            self.class.versioned_class.delete_all ["#{self.class.version_column} <= ? and #{self.class.versioned_foreign_key} = ?", excess_baggage, id]
+          end
+        end
+
+        # Reverts a model to a given version.  Takes either a version number or an instance of the versioned model
+        def revert_to(version)
+          if version.is_a?(self.class.versioned_class)
+            return false unless version.send(self.class.versioned_foreign_key) == id and !version.new_record?
+          else
+            return false unless version = versions.send("find_by_#{self.class.version_column}", version)
+          end
+          self.clone_versioned_model(version, self)
+          send("#{self.class.version_column}=", version.send(self.class.version_column))
+          true
+        end
+
+        # Reverts a model to a given version and saves the model.
+        # Takes either a version number or an instance of the versioned model
+        def revert_to!(version)
+          revert_to(version) ? save_without_revision : false
+        end
+
+        # Temporarily turns off Optimistic Locking while saving.  Used when reverting so that a new version is not created.
+        def save_without_revision
+          save_without_revision!
+          true
+        rescue
+          false
+        end
+
+        def save_without_revision!
+          without_locking do
+            without_revision do
+              save!
+            end
+          end
+        end
+
+        def altered?
+          track_altered_attributes ? (version_if_changed - changed).length < version_if_changed.length : versioned_fields_changed?
+        end
+
+        def versioned_fields_changed?
+          fields =  non_alone_versioned_columns | non_versioned_columns
+          !(changed_attributes.empty? || (fields | changed_attributes.keys == fields))
+        end
+
+        # Clones a model.  Used when saving a new version or reverting a model's version.
+        def clone_versioned_model(orig_model, new_model)
+          self.class.versioned_columns.each do |col|
+            new_model.send("#{col.name}=", orig_model.send(col.name)) if orig_model.has_attribute?(col.name)
+          end
+
+          if orig_model.is_a?(self.class.versioned_class)
+            new_model[new_model.class.inheritance_column] = orig_model[self.class.versioned_inheritance_column]
+          elsif new_model.is_a?(self.class.versioned_class)
+            new_model[self.class.versioned_inheritance_column] = orig_model[orig_model.class.inheritance_column]
+          end
+        end
+
+        # Checks whether a new version shall be saved or not.  Calls <tt>version_condition_met?</tt> and <tt>changed?</tt>.
+        def save_version?
+          version_condition_met? && altered?
+        end
+
+        # Checks condition set in the :if option to check whether a revision should be created or not.  Override this for
+        # custom version condition checking.
+        def version_condition_met?
+          case
+          when version_condition.is_a?(Symbol)
+            send(version_condition)
+          when version_condition.respond_to?(:call) && (version_condition.arity == 1 || version_condition.arity == -1)
+            version_condition.call(self)
+          else
+            version_condition
+          end
+        end
+
+        # Executes the block with the versioning callbacks disabled.
+        #
+        #   @foo.without_revision do
+        #     @foo.save
+        #   end
+        #
+        def without_revision(&block)
+          self.class.without_revision(&block)
+        end
+
+        # Turns off optimistic locking for the duration of the block
+        #
+        #   @foo.without_locking do
+        #     @foo.save
+        #   end
+        #
+        def without_locking(&block)
+          self.class.without_locking(&block)
+        end
+
+        def empty_callback() end #:nodoc:
+
+        protected
+          # sets the new version before saving, unless you're using optimistic locking.  In that case, let it take care of the version.
+          def set_new_version
+            @saving_version = new_record? || save_version?
+            self.send("#{self.class.version_column}=", next_version) if new_record? || (!locking_enabled? && save_version?)
+          end
+
+          # Gets the next available version for the current record, or 1 for a new record
+          def next_version
+            (new_record? ? 0 : versions.calculate(:max, version_column).to_i) + 1
+          end
+
+        module ClassMethods
+          # Returns an array of columns that are versioned.  See non_versioned_columns
+          def versioned_columns
+            @versioned_columns ||= columns.select { |c| !non_versioned_columns.include?(c.name) }
+          end
+
+          # Returns an instance of the dynamic versioned model
+          def versioned_class
+            const_get versioned_class_name
+          end
+
+          # Rake migration task to create the versioned table using options passed to acts_as_versioned
+          def create_versioned_table(create_table_options = {})
+            # create version column in main table if it does not exist
+            if !self.content_columns.find { |c| [version_column.to_s, 'lock_version'].include? c.name }
+              self.connection.add_column table_name, version_column, :integer
+              self.reset_column_information
+            end
+
+            return if connection.table_exists?(versioned_table_name)
+
+            self.connection.create_table(versioned_table_name, create_table_options) do |t|
+              t.column versioned_foreign_key, :integer
+              t.column version_column, :integer
+            end
+
+            self.versioned_columns.each do |col| 
+              self.connection.add_column versioned_table_name, col.name, col.type, 
+                :limit     => col.limit, 
+                :default   => col.default,
+                :scale     => col.scale,
+                :precision => col.precision
+            end
+
+            if type_col = self.columns_hash[inheritance_column]
+              self.connection.add_column versioned_table_name, versioned_inheritance_column, type_col.type, 
+                :limit     => type_col.limit, 
+                :default   => type_col.default,
+                :scale     => type_col.scale,
+                :precision => type_col.precision
+            end
+
+            self.connection.add_index versioned_table_name, versioned_foreign_key
+          end
+
+          # Rake migration task to drop the versioned table
+          def drop_versioned_table
+            self.connection.drop_table versioned_table_name
+          end
+
+          # Executes the block with the versioning callbacks disabled.
+          #
+          #   Foo.without_revision do
+          #     @foo.save
+          #   end
+          #
+          def without_revision(&block)
+            class_eval do 
+              CALLBACKS.each do |attr_name|
+                alias_method "orig_#{attr_name}".to_sym, attr_name
+                alias_method attr_name, :empty_callback
+              end
+            end
+            block.call
+          ensure
+            class_eval do 
+              CALLBACKS.each do |attr_name|
+                alias_method attr_name, "orig_#{attr_name}".to_sym
+              end
+            end
+          end
+
+          # Turns off optimistic locking for the duration of the block
+          #
+          #   Foo.without_locking do
+          #     @foo.save
+          #   end
+          #
+          def without_locking(&block)
+            current = ActiveRecord::Base.lock_optimistically
+            ActiveRecord::Base.lock_optimistically = false if current
+            result = block.call
+            ActiveRecord::Base.lock_optimistically = true if current
+            result
+          end
+        end
+      end
+    end
+  end
+end
+
+ActiveRecord::Base.send :include, ActiveRecord::Acts::Versioned