Merge commit 'mainstream/master'

20 files changed, 618 insertions, 663 deletions

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 66aa9332c8..7f299b2aa5 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1367,7 +1367,7 @@ module ActiveRecord
 
             define_method("#{reflection.name.to_s.singularize}_ids=") do |new_value|
               ids = (new_value || []).reject { |nid| nid.blank? }
-              send("#{reflection.name}=", reflection.class_name.constantize.find(ids))
+              send("#{reflection.name}=", reflection.klass.find(ids))
             end
           end
         end
@@ -1912,7 +1912,7 @@ module ActiveRecord
                     descendant
                   end.flatten.compact
 
-                  remove_duplicate_results!(reflection.class_name.constantize, parent_records, associations[name]) unless parent_records.empty?
+                  remove_duplicate_results!(reflection.klass, parent_records, associations[name]) unless parent_records.empty?
                 end
             end
           end
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index e21ef90391..f4507c979c 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -8,6 +8,8 @@ module ActiveRecord
       alias_method :new, :build
 
       def create!(attrs = nil)
+        ensure_owner_is_not_new
+
         transaction do
           self << (object = attrs ? @reflection.klass.send(:with_scope, :create => attrs) { @reflection.create_association! } : @reflection.create_association!)
           object
@@ -15,6 +17,8 @@ module ActiveRecord
       end
 
       def create(attrs = nil)
+        ensure_owner_is_not_new
+
         transaction do
           self << (object = attrs ? @reflection.klass.send(:with_scope, :create => attrs) { @reflection.create_association } : @reflection.create_association)
           object
@@ -50,7 +54,7 @@ module ActiveRecord
           options[:select]  = construct_select(options[:select])
           options[:from]  ||= construct_from
           options[:joins]   = construct_joins(options[:joins])
-          options[:include] = @reflection.source_reflection.options[:include] if options[:include].nil?
+          options[:include] = @reflection.source_reflection.options[:include] if options[:include].nil? && @reflection.source_reflection.options[:include]
         end
         
         def insert_record(record, force = true, validate = true)
diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index ecd2d57a5a..ab7ad34b9e 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -3,100 +3,13 @@ require 'active_support/core_ext/enumerable'
 module ActiveRecord
   module AttributeMethods #:nodoc:
     extend ActiveSupport::Concern
+    include ActiveModel::AttributeMethods
 
-    DEFAULT_SUFFIXES = %w(= ? _before_type_cast)
-    ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = [:datetime, :timestamp, :time, :date]
-
-    included do
-      attribute_method_suffix(*DEFAULT_SUFFIXES)
-
-      cattr_accessor :attribute_types_cached_by_default, :instance_writer => false
-      self.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
-
-      cattr_accessor :time_zone_aware_attributes, :instance_writer => false
-      self.time_zone_aware_attributes = false
-
-      class_inheritable_accessor :skip_time_zone_conversion_for_attributes, :instance_writer => false
-      self.skip_time_zone_conversion_for_attributes = []
-    end
-
-    # Declare and check for suffixed attribute methods.
     module ClassMethods
-      # Declares a method available for all attributes with the given suffix.
-      # Uses +method_missing+ and <tt>respond_to?</tt> to rewrite the method
-      #
-      #   #{attr}#{suffix}(*args, &block)
-      #
-      # to
-      #
-      #   attribute#{suffix}(#{attr}, *args, &block)
-      #
-      # An <tt>attribute#{suffix}</tt> instance method must exist and accept at least
-      # the +attr+ argument.
-      #
-      # For example:
-      #
-      #   class Person < ActiveRecord::Base
-      #     attribute_method_suffix '_changed?'
-      #
-      #     private
-      #       def attribute_changed?(attr)
-      #         ...
-      #       end
-      #   end
-      #
-      #   person = Person.find(1)
-      #   person.name_changed?    # => false
-      #   person.name = 'Hubert'
-      #   person.name_changed?    # => true
-      def attribute_method_suffix(*suffixes)
-        attribute_method_suffixes.concat suffixes
-        rebuild_attribute_method_regexp
-      end
-
-      # Returns MatchData if method_name is an attribute method.
-      def match_attribute_method?(method_name)
-        rebuild_attribute_method_regexp unless defined?(@@attribute_method_regexp) && @@attribute_method_regexp
-        @@attribute_method_regexp.match(method_name)
-      end
-
-
-      # Contains the names of the generated attribute methods.
-      def generated_methods #:nodoc:
-        @generated_methods ||= Set.new
-      end
-      
-      def generated_methods?
-        !generated_methods.empty?
-      end
-      
       # Generates all the attribute related methods for columns in the database
       # accessors, mutators and query methods.
       def define_attribute_methods
-        return if generated_methods?
-        columns_hash.each do |name, column|
-          unless instance_method_already_implemented?(name)
-            if self.serialized_attributes[name]
-              define_read_method_for_serialized_attribute(name)
-            elsif create_time_zone_conversion_attribute?(name, column)
-              define_read_method_for_time_zone_conversion(name)
-            else
-              define_read_method(name.to_sym, name, column)
-            end
-          end
-
-          unless instance_method_already_implemented?("#{name}=")
-            if create_time_zone_conversion_attribute?(name, column)
-              define_write_method_for_time_zone_conversion(name)
-            else  
-              define_write_method(name.to_sym)
-            end
-          end
-
-          unless instance_method_already_implemented?("#{name}?")
-            define_question_method(name)
-          end
-        end
+        super(columns_hash.keys)
       end
 
       # Checks whether the method is defined in the model or any of its subclasses
@@ -104,296 +17,35 @@ module ActiveRecord
       # method is defined by Active Record though.
       def instance_method_already_implemented?(method_name)
         method_name = method_name.to_s
-        return true if method_name =~ /^id(=$|\?$|$)/
         @_defined_class_methods         ||= ancestors.first(ancestors.index(ActiveRecord::Base)).sum([]) { |m| m.public_instance_methods(false) | m.private_instance_methods(false) | m.protected_instance_methods(false) }.map {|m| m.to_s }.to_set
         @@_defined_activerecord_methods ||= (ActiveRecord::Base.public_instance_methods(false) | ActiveRecord::Base.private_instance_methods(false) | ActiveRecord::Base.protected_instance_methods(false)).map{|m| m.to_s }.to_set
         raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord" if @@_defined_activerecord_methods.include?(method_name)
         @_defined_class_methods.include?(method_name)
       end
-      
-      alias :define_read_methods :define_attribute_methods
-
-      # +cache_attributes+ allows you to declare which converted attribute values should
-      # be cached. Usually caching only pays off for attributes with expensive conversion
-      # methods, like time related columns (e.g. +created_at+, +updated_at+).
-      def cache_attributes(*attribute_names)
-        attribute_names.each {|attr| cached_attributes << attr.to_s}
-      end
-
-      # Returns the attributes which are cached. By default time related columns
-      # with datatype <tt>:datetime, :timestamp, :time, :date</tt> are cached.
-      def cached_attributes
-        @cached_attributes ||=
-          columns.select{|c| attribute_types_cached_by_default.include?(c.type)}.map{|col| col.name}.to_set
-      end
-
-      # Returns +true+ if the provided attribute is being cached.
-      def cache_attribute?(attr_name)
-        cached_attributes.include?(attr_name)
-      end
-
-      private
-
-        # Suffixes a, ?, c become regexp /(a|\?|c)$/
-        def rebuild_attribute_method_regexp
-          suffixes = attribute_method_suffixes.map { |s| Regexp.escape(s) }
-          @@attribute_method_regexp = /(#{suffixes.join('|')})$/.freeze
-        end
-
-        # Default to =, ?, _before_type_cast
-        def attribute_method_suffixes
-          @@attribute_method_suffixes ||= []
-        end
-        
-        def create_time_zone_conversion_attribute?(name, column)
-          time_zone_aware_attributes && !skip_time_zone_conversion_for_attributes.include?(name.to_sym) && [:datetime, :timestamp].include?(column.type)
-        end
-        
-        # Define an attribute reader method.  Cope with nil column.
-        def define_read_method(symbol, attr_name, column)
-          cast_code = column.type_cast_code('v') if column
-          access_code = cast_code ? "(v=@attributes['#{attr_name}']) && #{cast_code}" : "@attributes['#{attr_name}']"
-
-          unless attr_name.to_s == self.primary_key.to_s
-            access_code = access_code.insert(0, "missing_attribute('#{attr_name}', caller) unless @attributes.has_key?('#{attr_name}'); ")
-          end
-          
-          if cache_attribute?(attr_name)
-            access_code = "@attributes_cache['#{attr_name}'] ||= (#{access_code})"
-          end
-          evaluate_attribute_method attr_name, "def #{symbol}; #{access_code}; end"
-        end
-
-        # Define read method for serialized attribute.
-        def define_read_method_for_serialized_attribute(attr_name)
-          evaluate_attribute_method attr_name, "def #{attr_name}; unserialize_attribute('#{attr_name}'); end"
-        end
-        
-        # Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
-        # This enhanced read method automatically converts the UTC time stored in the database to the time zone stored in Time.zone.
-        def define_read_method_for_time_zone_conversion(attr_name)
-          method_body = <<-EOV
-            def #{attr_name}(reload = false)
-              cached = @attributes_cache['#{attr_name}']
-              return cached if cached && !reload
-              time = read_attribute('#{attr_name}')
-              @attributes_cache['#{attr_name}'] = time.acts_like?(:time) ? time.in_time_zone : time
-            end
-          EOV
-          evaluate_attribute_method attr_name, method_body
-        end
-
-        # Defines a predicate method <tt>attr_name?</tt>.
-        def define_question_method(attr_name)
-          evaluate_attribute_method attr_name, "def #{attr_name}?; query_attribute('#{attr_name}'); end", "#{attr_name}?"
-        end
-
-        def define_write_method(attr_name)
-          evaluate_attribute_method attr_name, "def #{attr_name}=(new_value);write_attribute('#{attr_name}', new_value);end", "#{attr_name}="
-        end
-        
-        # Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
-        # This enhanced write method will automatically convert the time passed to it to the zone stored in Time.zone.
-        def define_write_method_for_time_zone_conversion(attr_name)
-          method_body = <<-EOV
-            def #{attr_name}=(time)
-              unless time.acts_like?(:time)
-                time = time.is_a?(String) ? Time.zone.parse(time) : time.to_time rescue time
-              end
-              time = time.in_time_zone rescue nil if time
-              write_attribute(:#{attr_name}, time)
-            end
-          EOV
-          evaluate_attribute_method attr_name, method_body, "#{attr_name}="
-        end
-
-        # Evaluate the definition for an attribute related method
-        def evaluate_attribute_method(attr_name, method_definition, method_name=attr_name)
-
-          unless method_name.to_s == primary_key.to_s
-            generated_methods << method_name
-          end
-
-          begin
-            class_eval(method_definition, __FILE__, __LINE__)
-          rescue SyntaxError => err
-            generated_methods.delete(attr_name)
-            if logger
-              logger.warn "Exception occurred during reader method compilation."
-              logger.warn "Maybe #{attr_name} is not a valid Ruby identifier?"
-              logger.warn err.message
-            end
-          end
-        end
-    end #  ClassMethods
-
+    end
 
-    # Allows access to the object attributes, which are held in the <tt>@attributes</tt> hash, as though they
-    # were first-class methods. So a Person class with a name attribute can use Person#name and
-    # Person#name= and never directly use the attributes hash -- except for multiple assigns with
-    # ActiveRecord#attributes=. A Milestone class can also ask Milestone#completed? to test that
-    # the completed attribute is not +nil+ or 0.
-    #
-    # It's also possible to instantiate related objects, so a Client class belonging to the clients
-    # table with a +master_id+ foreign key can instantiate master through Client#master.
     def method_missing(method_id, *args, &block)
-      method_name = method_id.to_s
-
       # If we haven't generated any methods yet, generate them, then
       # see if we've created the method we're looking for.
-      if !self.class.generated_methods?
+      if !self.class.attribute_methods_generated?
         self.class.define_attribute_methods
+        method_name = method_id.to_s
         guard_private_attribute_method!(method_name, args)
-        if self.class.generated_methods.include?(method_name)
+        if self.class.generated_attribute_methods.instance_methods.include?(method_name)
           return self.send(method_id, *args, &block)
         end
       end
-      
-      guard_private_attribute_method!(method_name, args)
-      if self.class.primary_key.to_s == method_name
-        id
-      elsif md = self.class.match_attribute_method?(method_name)
-        attribute_name, method_type = md.pre_match, md.to_s
-        if @attributes.include?(attribute_name)
-          __send__("attribute#{method_type}", attribute_name, *args, &block)
-        else
-          super
-        end
-      elsif @attributes.include?(method_name)
-        read_attribute(method_name)
-      else
-        super
-      end
-    end
-
-    # Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
-    # "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
-    def read_attribute(attr_name)
-      attr_name = attr_name.to_s
-      if !(value = @attributes[attr_name]).nil?
-        if column = column_for_attribute(attr_name)
-          if unserializable_attribute?(attr_name, column)
-            unserialize_attribute(attr_name)
-          else
-            column.type_cast(value)
-          end
-        else
-          value
-        end
-      else
-        nil
-      end
-    end
-
-    def read_attribute_before_type_cast(attr_name)
-      @attributes[attr_name]
-    end
-
-    # Returns true if the attribute is of a text column and marked for serialization.
-    def unserializable_attribute?(attr_name, column)
-      column.text? && self.class.serialized_attributes[attr_name]
-    end
-
-    # Returns the unserialized object of the attribute.
-    def unserialize_attribute(attr_name)
-      unserialized_object = object_from_yaml(@attributes[attr_name])
-
-      if unserialized_object.is_a?(self.class.serialized_attributes[attr_name]) || unserialized_object.nil?
-        @attributes.frozen? ? unserialized_object : @attributes[attr_name] = unserialized_object
-      else
-        raise SerializationTypeMismatch,
-          "#{attr_name} was supposed to be a #{self.class.serialized_attributes[attr_name]}, but was a #{unserialized_object.class.to_s}"
-      end
-    end
-  
-
-    # Updates the attribute identified by <tt>attr_name</tt> with the specified +value+. Empty strings for fixnum and float
-    # columns are turned into +nil+.
-    def write_attribute(attr_name, value)
-      attr_name = attr_name.to_s
-      @attributes_cache.delete(attr_name)
-      if (column = column_for_attribute(attr_name)) && column.number?
-        @attributes[attr_name] = convert_number_column_value(value)
-      else
-        @attributes[attr_name] = value
-      end
+      super
     end
 
-
-    def query_attribute(attr_name)
-      unless value = read_attribute(attr_name)
-        false
-      else
-        column = self.class.columns_hash[attr_name]
-        if column.nil?
-          if Numeric === value || value !~ /[^0-9]/
-            !value.to_i.zero?
-          else
-            return false if ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES.include?(value)
-            !value.blank?
-          end
-        elsif column.number?
-          !value.zero?
-        else
-          !value.blank?
-        end
-      end
-    end
-    
-    # A Person object with a name attribute can ask <tt>person.respond_to?(:name)</tt>,
-    # <tt>person.respond_to?(:name=)</tt>, and <tt>person.respond_to?(:name?)</tt>
-    # which will all return +true+.
-    alias :respond_to_without_attributes? :respond_to?
-    def respond_to?(method, include_private_methods = false)
-      method_name = method.to_s
-      if super
-        return true
-      elsif !include_private_methods && super(method, true)
-        # If we're here than we haven't found among non-private methods
-        # but found among all methods. Which means that given method is private.
-        return false
-      elsif !self.class.generated_methods?
-        self.class.define_attribute_methods
-        if self.class.generated_methods.include?(method_name)
-          return true
-        end
-      end
-        
-      if @attributes.nil?
-        return super
-      elsif @attributes.include?(method_name)
-        return true
-      elsif md = self.class.match_attribute_method?(method_name)
-        return true if @attributes.include?(md.pre_match)
-      end
+    def respond_to?(*args)
+      self.class.define_attribute_methods
       super
     end
 
-    private
-      # prevent method_missing from calling private methods with #send
-      def guard_private_attribute_method!(method_name, args)
-        if self.class.private_method_defined?(method_name)
-          raise NoMethodError.new("Attempt to call private method", method_name, args)
-        end
-      end
-    
-      def missing_attribute(attr_name, stack)
-        raise ActiveRecord::MissingAttributeError, "missing attribute: #{attr_name}", stack
-      end
-      
-      # Handle *? for method_missing.
-      def attribute?(attribute_name)
-        query_attribute(attribute_name)
-      end
-
-      # Handle *= for method_missing.
-      def attribute=(attribute_name, value)
-        write_attribute(attribute_name, value)
-      end
-
-      # Handle *_before_type_cast for method_missing.
-      def attribute_before_type_cast(attribute_name)
-        read_attribute_before_type_cast(attribute_name)
+    protected
+      def attribute_method?(attr_name)
+        attr_name == 'id' || attributes.include?(attr_name)
       end
   end
 end
diff --git a/activerecord/lib/active_record/attribute_methods/before_type_cast.rb b/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
new file mode 100644
index 0000000000..a4e144f233
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
@@ -0,0 +1,33 @@
+module ActiveRecord
+  module AttributeMethods
+    module BeforeTypeCast
+      extend ActiveSupport::Concern
+
+      included do
+        attribute_method_suffix "_before_type_cast"
+      end
+
+      def read_attribute_before_type_cast(attr_name)
+        @attributes[attr_name]
+      end
+
+      # Returns a hash of attributes before typecasting and deserialization.
+      def attributes_before_type_cast
+        self.attribute_names.inject({}) do |attrs, name|
+          attrs[name] = read_attribute_before_type_cast(name)
+          attrs
+        end
+      end
+
+      private
+        # Handle *_before_type_cast for method_missing.
+        def attribute_before_type_cast(attribute_name)
+          if attribute_name == 'id'
+            read_attribute_before_type_cast(self.class.primary_key)
+          else
+            read_attribute_before_type_cast(attribute_name)
+          end
+        end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
new file mode 100644
index 0000000000..911c908c8b
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -0,0 +1,204 @@
+module ActiveRecord
+  module AttributeMethods
+    # Track unsaved attribute changes.
+    #
+    # A newly instantiated object is unchanged:
+    #   person = Person.find_by_name('Uncle Bob')
+    #   person.changed?       # => false
+    #
+    # Change the name:
+    #   person.name = 'Bob'
+    #   person.changed?       # => true
+    #   person.name_changed?  # => true
+    #   person.name_was       # => 'Uncle Bob'
+    #   person.name_change    # => ['Uncle Bob', 'Bob']
+    #   person.name = 'Bill'
+    #   person.name_change    # => ['Uncle Bob', 'Bill']
+    #
+    # Save the changes:
+    #   person.save
+    #   person.changed?       # => false
+    #   person.name_changed?  # => false
+    #
+    # Assigning the same value leaves the attribute unchanged:
+    #   person.name = 'Bill'
+    #   person.name_changed?  # => false
+    #   person.name_change    # => nil
+    #
+    # Which attributes have changed?
+    #   person.name = 'Bob'
+    #   person.changed        # => ['name']
+    #   person.changes        # => { 'name' => ['Bill', 'Bob'] }
+    #
+    # Resetting an attribute returns it to its original state:
+    #   person.reset_name!    # => 'Bill'
+    #   person.changed?       # => false
+    #   person.name_changed?  # => false
+    #   person.name           # => 'Bill'
+    #
+    # Before modifying an attribute in-place:
+    #   person.name_will_change!
+    #   person.name << 'y'
+    #   person.name_change    # => ['Bill', 'Billy']
+    module Dirty
+      extend ActiveSupport::Concern
+
+      DIRTY_AFFIXES = [
+        { :suffix => '_changed?' },
+        { :suffix => '_change' },
+        { :suffix => '_will_change!' },
+        { :suffix => '_was' },
+        { :prefix => 'reset_', :suffix => '!' }
+      ]
+
+      included do
+        attribute_method_affix *DIRTY_AFFIXES
+
+        alias_method_chain :save,            :dirty
+        alias_method_chain :save!,           :dirty
+        alias_method_chain :update,          :dirty
+        alias_method_chain :reload,          :dirty
+
+        superclass_delegating_accessor :partial_updates
+        self.partial_updates = true
+      end
+
+      # Do any attributes have unsaved changes?
+      #   person.changed? # => false
+      #   person.name = 'bob'
+      #   person.changed? # => true
+      def changed?
+        !changed_attributes.empty?
+      end
+
+      # List of attributes with unsaved changes.
+      #   person.changed # => []
+      #   person.name = 'bob'
+      #   person.changed # => ['name']
+      def changed
+        changed_attributes.keys
+      end
+
+      # Map of changed attrs => [original value, new value].
+      #   person.changes # => {}
+      #   person.name = 'bob'
+      #   person.changes # => { 'name' => ['bill', 'bob'] }
+      def changes
+        changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h }
+      end
+
+      # Attempts to +save+ the record and clears changed attributes if successful.
+      def save_with_dirty(*args) #:nodoc:
+        if status = save_without_dirty(*args)
+          changed_attributes.clear
+        end
+        status
+      end
+
+      # Attempts to <tt>save!</tt> the record and clears changed attributes if successful.
+      def save_with_dirty!(*args) #:nodoc:
+        status = save_without_dirty!(*args)
+        changed_attributes.clear
+        status
+      end
+
+      # <tt>reload</tt> the record and clears changed attributes.
+      def reload_with_dirty(*args) #:nodoc:
+        record = reload_without_dirty(*args)
+        changed_attributes.clear
+        record
+      end
+
+      private
+        # Map of change <tt>attr => original value</tt>.
+        def changed_attributes
+          @changed_attributes ||= {}
+        end
+
+        # Handle <tt>*_changed?</tt> for +method_missing+.
+        def attribute_changed?(attr)
+          changed_attributes.include?(attr)
+        end
+
+        # Handle <tt>*_change</tt> for +method_missing+.
+        def attribute_change(attr)
+          [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
+        end
+
+        # Handle <tt>*_was</tt> for +method_missing+.
+        def attribute_was(attr)
+          attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
+        end
+
+        # Handle <tt>reset_*!</tt> for +method_missing+.
+        def reset_attribute!(attr)
+          self[attr] = changed_attributes[attr] if attribute_changed?(attr)
+        end
+
+        # Handle <tt>*_will_change!</tt> for +method_missing+.
+        def attribute_will_change!(attr)
+          changed_attributes[attr] = clone_attribute_value(:read_attribute, attr)
+        end
+
+        # Wrap write_attribute to remember original attribute value.
+        def write_attribute(attr, value)
+          attr = attr.to_s
+
+          # The attribute already has an unsaved change.
+          if changed_attributes.include?(attr)
+            old = changed_attributes[attr]
+            changed_attributes.delete(attr) unless field_changed?(attr, old, value)
+          else
+            old = clone_attribute_value(:read_attribute, attr)
+            changed_attributes[attr] = old if field_changed?(attr, old, value)
+          end
+
+          # Carry on.
+          super(attr, value)
+        end
+
+        def update_with_dirty
+          if partial_updates?
+            # Serialized attributes should always be written in case they've been
+            # changed in place.
+            update_without_dirty(changed | (attributes.keys & self.class.serialized_attributes.keys))
+          else
+            update_without_dirty
+          end
+        end
+
+        def field_changed?(attr, old, value)
+          if column = column_for_attribute(attr)
+            if column.number? && column.null && (old.nil? || old == 0) && value.blank?
+              # For nullable numeric columns, NULL gets stored in database for blank (i.e. '') values.
+              # Hence we don't record it as a change if the value changes from nil to ''.
+              # If an old value of 0 is set to '' we want this to get changed to nil as otherwise it'll
+              # be typecast back to 0 (''.to_i => 0)
+              value = nil
+            else
+              value = column.type_cast(value)
+            end
+          end
+
+          old != value
+        end
+
+      module ClassMethods
+        def self.extended(base)
+          class << base
+            alias_method_chain :alias_attribute, :dirty
+          end
+        end
+
+        def alias_attribute_with_dirty(new_name, old_name)
+          alias_attribute_without_dirty(new_name, old_name)
+          DIRTY_AFFIXES.each do |affixes|
+            module_eval <<-STR, __FILE__, __LINE__+1
+              def #{affixes[:prefix]}#{new_name}#{affixes[:suffix]}; self.#{affixes[:prefix]}#{old_name}#{affixes[:suffix]}; end  # def reset_subject!; self.reset_title!; end
+            STR
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
new file mode 100644
index 0000000000..365fdeb55a
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -0,0 +1,44 @@
+module ActiveRecord
+  module AttributeMethods
+    module PrimaryKey
+      extend ActiveSupport::Concern
+
+      module ClassMethods
+        # Defines the primary key field -- can be overridden in subclasses. Overwriting will negate any effect of the
+        # primary_key_prefix_type setting, though.
+        def primary_key
+          reset_primary_key
+        end
+
+        def reset_primary_key #:nodoc:
+          key = get_primary_key(base_class.name)
+          set_primary_key(key)
+          key
+        end
+
+        def get_primary_key(base_name) #:nodoc:
+          key = 'id'
+          case primary_key_prefix_type
+            when :table_name
+              key = base_name.to_s.foreign_key(false)
+            when :table_name_with_underscore
+              key = base_name.to_s.foreign_key
+          end
+          key
+        end
+
+        # Sets the name of the primary key column to use to the given value,
+        # or (if the value is nil or false) to the value returned by the given
+        # block.
+        #
+        #   class Project < ActiveRecord::Base
+        #     set_primary_key "sysid"
+        #   end
+        def set_primary_key(value = nil, &block)
+          define_attr_method :primary_key, value, &block
+        end
+        alias :primary_key= :set_primary_key
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_methods/query.rb b/activerecord/lib/active_record/attribute_methods/query.rb
new file mode 100644
index 0000000000..a949d80120
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_methods/query.rb
@@ -0,0 +1,37 @@
+module ActiveRecord
+  module AttributeMethods
+    module Query
+      extend ActiveSupport::Concern
+
+      included do
+        attribute_method_suffix "?"
+      end
+
+      def query_attribute(attr_name)
+        unless value = read_attribute(attr_name)
+          false
+        else
+          column = self.class.columns_hash[attr_name]
+          if column.nil?
+            if Numeric === value || value !~ /[^0-9]/
+              !value.to_i.zero?
+            else
+              return false if ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES.include?(value)
+              !value.blank?
+            end
+          elsif column.number?
+            !value.zero?
+          else
+            !value.blank?
+          end
+        end
+      end
+
+      private
+        # Handle *? for method_missing.
+        def attribute?(attribute_name)
+          query_attribute(attribute_name)
+        end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_methods/read.rb b/activerecord/lib/active_record/attribute_methods/read.rb
new file mode 100644
index 0000000000..3da3d9d8cc
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_methods/read.rb
@@ -0,0 +1,116 @@
+module ActiveRecord
+  module AttributeMethods
+    module Read
+      extend ActiveSupport::Concern
+
+      ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = [:datetime, :timestamp, :time, :date]
+
+      included do
+        attribute_method_suffix ""
+
+        cattr_accessor :attribute_types_cached_by_default, :instance_writer => false
+        self.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
+
+        # Undefine id so it can be used as an attribute name
+        undef_method(:id) if method_defined?(:id)
+      end
+
+      module ClassMethods
+        # +cache_attributes+ allows you to declare which converted attribute values should
+        # be cached. Usually caching only pays off for attributes with expensive conversion
+        # methods, like time related columns (e.g. +created_at+, +updated_at+).
+        def cache_attributes(*attribute_names)
+          attribute_names.each {|attr| cached_attributes << attr.to_s}
+        end
+
+        # Returns the attributes which are cached. By default time related columns
+        # with datatype <tt>:datetime, :timestamp, :time, :date</tt> are cached.
+        def cached_attributes
+          @cached_attributes ||=
+            columns.select{|c| attribute_types_cached_by_default.include?(c.type)}.map{|col| col.name}.to_set
+        end
+
+        # Returns +true+ if the provided attribute is being cached.
+        def cache_attribute?(attr_name)
+          cached_attributes.include?(attr_name)
+        end
+
+        protected
+          def define_method_attribute(attr_name)
+            if self.serialized_attributes[attr_name]
+              define_read_method_for_serialized_attribute(attr_name)
+            else
+              define_read_method(attr_name.to_sym, attr_name, columns_hash[attr_name])
+            end
+
+            if attr_name == primary_key && attr_name != "id"
+              define_read_method(:id, attr_name, columns_hash[attr_name])
+            end
+          end
+
+        private
+          # Define read method for serialized attribute.
+          def define_read_method_for_serialized_attribute(attr_name)
+            generated_attribute_methods.module_eval("def #{attr_name}; unserialize_attribute('#{attr_name}'); end", __FILE__, __LINE__)
+          end
+
+          # Define an attribute reader method.  Cope with nil column.
+          def define_read_method(symbol, attr_name, column)
+            cast_code = column.type_cast_code('v') if column
+            access_code = cast_code ? "(v=@attributes['#{attr_name}']) && #{cast_code}" : "@attributes['#{attr_name}']"
+
+            unless attr_name.to_s == self.primary_key.to_s
+              access_code = access_code.insert(0, "missing_attribute('#{attr_name}', caller) unless @attributes.has_key?('#{attr_name}'); ")
+            end
+
+            if cache_attribute?(attr_name)
+              access_code = "@attributes_cache['#{attr_name}'] ||= (#{access_code})"
+            end
+            generated_attribute_methods.module_eval("def #{symbol}; #{access_code}; end", __FILE__, __LINE__)
+          end
+      end
+
+      # Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
+      # "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
+      def read_attribute(attr_name)
+        attr_name = attr_name.to_s
+        attr_name = self.class.primary_key if attr_name == 'id'
+        if !(value = @attributes[attr_name]).nil?
+          if column = column_for_attribute(attr_name)
+            if unserializable_attribute?(attr_name, column)
+              unserialize_attribute(attr_name)
+            else
+              column.type_cast(value)
+            end
+          else
+            value
+          end
+        else
+          nil
+        end
+      end
+
+      # Returns true if the attribute is of a text column and marked for serialization.
+      def unserializable_attribute?(attr_name, column)
+        column.text? && self.class.serialized_attributes[attr_name]
+      end
+
+      # Returns the unserialized object of the attribute.
+      def unserialize_attribute(attr_name)
+        unserialized_object = object_from_yaml(@attributes[attr_name])
+
+        if unserialized_object.is_a?(self.class.serialized_attributes[attr_name]) || unserialized_object.nil?
+          @attributes.frozen? ? unserialized_object : @attributes[attr_name] = unserialized_object
+        else
+          raise SerializationTypeMismatch,
+            "#{attr_name} was supposed to be a #{self.class.serialized_attributes[attr_name]}, but was a #{unserialized_object.class.to_s}"
+        end
+      end
+
+      private
+        def attribute(attribute_name)
+          read_attribute(attribute_name)
+        end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
new file mode 100644
index 0000000000..a8e3e28a7a
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
@@ -0,0 +1,60 @@
+module ActiveRecord
+  module AttributeMethods
+    module TimeZoneConversion
+      extend ActiveSupport::Concern
+
+      included do
+        cattr_accessor :time_zone_aware_attributes, :instance_writer => false
+        self.time_zone_aware_attributes = false
+
+        class_inheritable_accessor :skip_time_zone_conversion_for_attributes, :instance_writer => false
+        self.skip_time_zone_conversion_for_attributes = []
+      end
+
+      module ClassMethods
+        protected
+          # Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
+          # This enhanced read method automatically converts the UTC time stored in the database to the time zone stored in Time.zone.
+          def define_method_attribute(attr_name)
+            if create_time_zone_conversion_attribute?(attr_name, columns_hash[attr_name])
+              method_body = <<-EOV
+                def #{attr_name}(reload = false)
+                  cached = @attributes_cache['#{attr_name}']
+                  return cached if cached && !reload
+                  time = read_attribute('#{attr_name}')
+                  @attributes_cache['#{attr_name}'] = time.acts_like?(:time) ? time.in_time_zone : time
+                end
+              EOV
+              generated_attribute_methods.module_eval(method_body, __FILE__, __LINE__)
+            else
+              super
+            end
+          end
+
+          # Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
+          # This enhanced write method will automatically convert the time passed to it to the zone stored in Time.zone.
+          def define_method_attribute=(attr_name)
+            if create_time_zone_conversion_attribute?(attr_name, columns_hash[attr_name])
+              method_body = <<-EOV
+                def #{attr_name}=(time)
+                  unless time.acts_like?(:time)
+                    time = time.is_a?(String) ? Time.zone.parse(time) : time.to_time rescue time
+                  end
+                  time = time.in_time_zone rescue nil if time
+                  write_attribute(:#{attr_name}, time)
+                end
+              EOV
+              generated_attribute_methods.module_eval(method_body, __FILE__, __LINE__)
+            else
+              super
+            end
+          end
+
+        private
+          def create_time_zone_conversion_attribute?(name, column)
+            time_zone_aware_attributes && !skip_time_zone_conversion_for_attributes.include?(name.to_sym) && [:datetime, :timestamp].include?(column.type)
+          end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
new file mode 100644
index 0000000000..e31acac050
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -0,0 +1,37 @@
+module ActiveRecord
+  module AttributeMethods
+    module Write
+      extend ActiveSupport::Concern
+
+      included do
+        attribute_method_suffix "="
+      end
+
+      module ClassMethods
+        protected
+          def define_method_attribute=(attr_name)
+            generated_attribute_methods.module_eval("def #{attr_name}=(new_value); write_attribute('#{attr_name}', new_value); end", __FILE__, __LINE__)
+          end
+      end
+
+      # Updates the attribute identified by <tt>attr_name</tt> with the specified +value+. Empty strings for fixnum and float
+      # columns are turned into +nil+.
+      def write_attribute(attr_name, value)
+        attr_name = attr_name.to_s
+        attr_name = self.class.primary_key if attr_name == 'id'
+        @attributes_cache.delete(attr_name)
+        if (column = column_for_attribute(attr_name)) && column.number?
+          @attributes[attr_name] = convert_number_column_value(value)
+        else
+          @attributes[attr_name] = value
+        end
+      end
+
+      private
+        # Handle *= for method_missing.
+        def attribute=(attribute_name, value)
+          write_attribute(attribute_name, value)
+        end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 5a36ff5ba2..531a698f77 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -148,11 +148,6 @@ module ActiveRecord #:nodoc:
   class DangerousAttributeError < ActiveRecordError
   end
 
-  # Raised when you've tried to access a column which wasn't loaded by your finder.
-  # Typically this is because <tt>:select</tt> has been specified.
-  class MissingAttributeError < NoMethodError
-  end
-
   # Raised when unknown attributes are supplied via mass assignment.
   class UnknownAttributeError < NoMethodError
   end
@@ -1225,29 +1220,6 @@ module ActiveRecord #:nodoc:
         name
       end
 
-      # Defines the primary key field -- can be overridden in subclasses. Overwriting will negate any effect of the
-      # primary_key_prefix_type setting, though.
-      def primary_key
-        reset_primary_key
-      end
-
-      def reset_primary_key #:nodoc:
-        key = get_primary_key(base_class.name)
-        set_primary_key(key)
-        key
-      end
-
-      def get_primary_key(base_name) #:nodoc:
-        key = 'id'
-        case primary_key_prefix_type
-          when :table_name
-            key = base_name.to_s.foreign_key(false)
-          when :table_name_with_underscore
-            key = base_name.to_s.foreign_key
-        end
-        key
-      end
-
       # Defines the column name for use with single table inheritance
       # -- can be set in subclasses like so: self.inheritance_column = "type_id"
       def inheritance_column
@@ -1277,18 +1249,6 @@ module ActiveRecord #:nodoc:
       end
       alias :table_name= :set_table_name
 
-      # Sets the name of the primary key column to use to the given value,
-      # or (if the value is nil or false) to the value returned by the given
-      # block.
-      #
-      #   class Project < ActiveRecord::Base
-      #     set_primary_key "sysid"
-      #   end
-      def set_primary_key(value = nil, &block)
-        define_attr_method :primary_key, value, &block
-      end
-      alias :primary_key= :set_primary_key
-
       # Sets the name of the inheritance column to use to the given value,
       # or (if the value # is nil or false) to the value returned by the
       # given block.
@@ -1401,8 +1361,8 @@ module ActiveRecord #:nodoc:
       #    end
       #  end
       def reset_column_information
-        generated_methods.each { |name| undef_method(name) }
-        @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @generated_methods = @inheritance_column = nil
+        undefine_attribute_methods
+        @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @inheritance_column = nil
       end
 
       def reset_column_information_and_inheritable_attributes_for_all_subclasses#:nodoc:
@@ -2077,36 +2037,6 @@ module ActiveRecord #:nodoc:
           end
         end
 
-        # Defines an "attribute" method (like +inheritance_column+ or
-        # +table_name+). A new (class) method will be created with the
-        # given name. If a value is specified, the new method will
-        # return that value (as a string). Otherwise, the given block
-        # will be used to compute the value of the method.
-        #
-        # The original method will be aliased, with the new name being
-        # prefixed with "original_". This allows the new method to
-        # access the original value.
-        #
-        # Example:
-        #
-        #   class A < ActiveRecord::Base
-        #     define_attr_method :primary_key, "sysid"
-        #     define_attr_method( :inheritance_column ) do
-        #       original_inheritance_column + "_id"
-        #     end
-        #   end
-        def define_attr_method(name, value=nil, &block)
-          sing = metaclass
-          sing.send :alias_method, "original_#{name}", name
-          if block_given?
-            sing.send :define_method, name, &block
-          else
-            # use eval instead of a block to work around a memory leak in dev
-            # mode in fcgi
-            sing.class_eval "def #{name}; #{value.to_s.inspect}; end"
-          end
-        end
-
       protected
         # Scope parameters to method calls within the block.  Takes a hash of method_name => parameters hash.
         # method_name may be <tt>:find</tt> or <tt>:create</tt>. <tt>:find</tt> parameters may include the <tt>:conditions</tt>, <tt>:joins</tt>,
@@ -2508,18 +2438,6 @@ module ActiveRecord #:nodoc:
         result
       end
 
-      # A model instance's primary key is always available as model.id
-      # whether you name it the default 'id' or set it to something else.
-      def id
-        attr_name = self.class.primary_key
-        column = column_for_attribute(attr_name)
-
-        self.class.send(:define_read_method, :id, attr_name, column)
-        # now that the method exists, call it
-        self.send attr_name.to_sym
-
-      end
-
       # Returns a String, which Action Pack uses for constructing an URL to this
       # object. The default implementation returns this record's id as a String,
       # or nil if this record's unsaved.
@@ -2565,24 +2483,20 @@ module ActiveRecord #:nodoc:
         end
       end
 
-      def id_before_type_cast #:nodoc:
-        read_attribute_before_type_cast(self.class.primary_key)
-      end
-
       def quoted_id #:nodoc:
         quote_value(id, column_for_attribute(self.class.primary_key))
       end
 
-      # Sets the primary ID.
-      def id=(value)
-        write_attribute(self.class.primary_key, value)
-      end
-
       # Returns true if this object hasn't been saved yet -- that is, a record for the object doesn't exist yet; otherwise, returns false.
       def new_record?
         @new_record || false
       end
 
+      # Returns true if this object has been destroyed, otherwise returns false.
+      def destroyed?
+        @destroyed || false
+      end
+
       # :call-seq:
       #   save(perform_validation = true)
       #
@@ -2633,6 +2547,7 @@ module ActiveRecord #:nodoc:
       # options, use <tt>#destroy</tt>.
       def delete
         self.class.delete(id) unless new_record?
+        @destroyed = true
         freeze
       end
 
@@ -2647,6 +2562,7 @@ module ActiveRecord #:nodoc:
           )
         end
 
+        @destroyed = true
         freeze
       end
 
@@ -2822,14 +2738,6 @@ module ActiveRecord #:nodoc:
         end
       end
 
-      # Returns a hash of attributes before typecasting and deserialization.
-      def attributes_before_type_cast
-        self.attribute_names.inject({}) do |attrs, name|
-          attrs[name] = read_attribute_before_type_cast(name)
-          attrs
-        end
-      end
-
       # Returns an <tt>#inspect</tt>-like string for the value of the
       # attribute +attr_name+. String attributes are elided after 50
       # characters, and Date and Time attributes are returned in the
@@ -3212,7 +3120,10 @@ module ActiveRecord #:nodoc:
     include Validations
     include Locking::Optimistic, Locking::Pessimistic
     include AttributeMethods
-    include Dirty
+    include AttributeMethods::Read, AttributeMethods::Write, AttributeMethods::BeforeTypeCast, AttributeMethods::Query
+    include AttributeMethods::PrimaryKey
+    include AttributeMethods::TimeZoneConversion
+    include AttributeMethods::Dirty
     include Callbacks, ActiveModel::Observing, Timestamp
     include Associations, AssociationPreload, NamedScope
     include ActiveModel::Conversion
diff --git a/activerecord/lib/active_record/calculations.rb b/activerecord/lib/active_record/calculations.rb
index 727f4c1dc6..4a88c43dff 100644
--- a/activerecord/lib/active_record/calculations.rb
+++ b/activerecord/lib/active_record/calculations.rb
@@ -197,6 +197,8 @@ module ActiveRecord
           sql << ", #{options[:group_field]} AS #{options[:group_alias]}" if options[:group]
           if options[:from]
             sql << " FROM #{options[:from]} "
+          elsif scope && scope[:from]
+            sql << " FROM #{scope[:from]} "
           else
             sql << " FROM (SELECT #{distinct}#{column_name}" if use_workaround
             sql << " FROM #{connection.quote_table_name(table_name)} "
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb b/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
index 720fba29e9..8649f96498 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
@@ -60,7 +60,12 @@ module ActiveRecord
       end
 
       def quoted_date(value)
-        value.to_s(:db)
+        if value.acts_like?(:time)
+          zone_conversion_method = ActiveRecord::Base.default_timezone == :utc ? :getutc : :getlocal
+          value.respond_to?(zone_conversion_method) ? value.send(zone_conversion_method) : value
+        else
+          value
+        end.to_s(:db)
       end
 
       def quoted_string_prefix
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index 24c734cddb..f346e3ebc8 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -277,7 +277,6 @@ module ActiveRecord
         add_column_options!(column_sql, column_options) unless type.to_sym == :primary_key
         column_sql
       end
-      alias to_s :to_sql
 
       private
 
@@ -508,7 +507,7 @@ module ActiveRecord
       # concatenated together. This string can then be prepended and appended to
       # to generate the final SQL to create the table.
       def to_sql
-        @columns * ', '
+        @columns.map(&:to_sql) * ', '
       end
 
       private
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 83cb9cff15..2b882a1f25 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -587,6 +587,10 @@ module ActiveRecord
             @connection.ssl_set(@config[:sslkey], @config[:sslcert], @config[:sslca], @config[:sslcapath], @config[:sslcipher])
           end
 
+          @connection.options(Mysql::OPT_CONNECT_TIMEOUT, @config[:connect_timeout]) if @config[:connect_timeout]
+          @connection.options(Mysql::OPT_READ_TIMEOUT, @config[:read_timeout]) if @config[:read_timeout]
+          @connection.options(Mysql::OPT_WRITE_TIMEOUT, @config[:write_timeout]) if @config[:write_timeout]
+
           @connection.real_connect(*@connection_options)
 
           # reconnect must be set after real_connect is called, because real_connect sets it to false internally
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
index 5e5e30776a..c0f5046bff 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
@@ -27,7 +27,6 @@ module ActiveRecord
 
       private
         def parse_sqlite_config!(config)
-          config[:database] ||= config[:dbfile]
           # Require database.
           unless config[:database]
             raise ArgumentError, "No database file specified. Missing argument: database"
diff --git a/activerecord/lib/active_record/dirty.rb b/activerecord/lib/active_record/dirty.rb
deleted file mode 100644
index 178767e0c3..0000000000
--- a/activerecord/lib/active_record/dirty.rb
+++ /dev/null
@@ -1,186 +0,0 @@
-module ActiveRecord
-  # Track unsaved attribute changes.
-  #
-  # A newly instantiated object is unchanged:
-  #   person = Person.find_by_name('uncle bob')
-  #   person.changed?       # => false
-  #
-  # Change the name:
-  #   person.name = 'Bob'
-  #   person.changed?       # => true
-  #   person.name_changed?  # => true
-  #   person.name_was       # => 'uncle bob'
-  #   person.name_change    # => ['uncle bob', 'Bob']
-  #   person.name = 'Bill'
-  #   person.name_change    # => ['uncle bob', 'Bill']
-  #
-  # Save the changes:
-  #   person.save
-  #   person.changed?       # => false
-  #   person.name_changed?  # => false
-  #
-  # Assigning the same value leaves the attribute unchanged:
-  #   person.name = 'Bill'
-  #   person.name_changed?  # => false
-  #   person.name_change    # => nil
-  #
-  # Which attributes have changed?
-  #   person.name = 'bob'
-  #   person.changed        # => ['name']
-  #   person.changes        # => { 'name' => ['Bill', 'bob'] }
-  #
-  # Before modifying an attribute in-place:
-  #   person.name_will_change!
-  #   person.name << 'by'
-  #   person.name_change    # => ['uncle bob', 'uncle bobby']
-  module Dirty
-    extend ActiveSupport::Concern
-
-    DIRTY_SUFFIXES = ['_changed?', '_change', '_will_change!', '_was']
-
-    included do
-      attribute_method_suffix *DIRTY_SUFFIXES
-
-      alias_method_chain :write_attribute, :dirty
-      alias_method_chain :save,            :dirty
-      alias_method_chain :save!,           :dirty
-      alias_method_chain :update,          :dirty
-      alias_method_chain :reload,          :dirty
-
-      superclass_delegating_accessor :partial_updates
-      self.partial_updates = true
-    end
-
-    # Do any attributes have unsaved changes?
-    #   person.changed? # => false
-    #   person.name = 'bob'
-    #   person.changed? # => true
-    def changed?
-      !changed_attributes.empty?
-    end
-
-    # List of attributes with unsaved changes.
-    #   person.changed # => []
-    #   person.name = 'bob'
-    #   person.changed # => ['name']
-    def changed
-      changed_attributes.keys
-    end
-
-    # Map of changed attrs => [original value, new value].
-    #   person.changes # => {}
-    #   person.name = 'bob'
-    #   person.changes # => { 'name' => ['bill', 'bob'] }
-    def changes
-      changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h }
-    end
-
-    # Attempts to +save+ the record and clears changed attributes if successful.
-    def save_with_dirty(*args) #:nodoc:
-      if status = save_without_dirty(*args)
-        changed_attributes.clear
-      end
-      status
-    end
-
-    # Attempts to <tt>save!</tt> the record and clears changed attributes if successful.
-    def save_with_dirty!(*args) #:nodoc:
-      status = save_without_dirty!(*args)
-      changed_attributes.clear
-      status
-    end
-
-    # <tt>reload</tt> the record and clears changed attributes.
-    def reload_with_dirty(*args) #:nodoc:
-      record = reload_without_dirty(*args)
-      changed_attributes.clear
-      record
-    end
-
-    private
-      # Map of change <tt>attr => original value</tt>.
-      def changed_attributes
-        @changed_attributes ||= {}
-      end
-
-      # Handle <tt>*_changed?</tt> for +method_missing+.
-      def attribute_changed?(attr)
-        changed_attributes.include?(attr)
-      end
-
-      # Handle <tt>*_change</tt> for +method_missing+.
-      def attribute_change(attr)
-        [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
-      end
-
-      # Handle <tt>*_was</tt> for +method_missing+.
-      def attribute_was(attr)
-        attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
-      end
-
-      # Handle <tt>*_will_change!</tt> for +method_missing+.
-      def attribute_will_change!(attr)
-        changed_attributes[attr] = clone_attribute_value(:read_attribute, attr)
-      end
-
-      # Wrap write_attribute to remember original attribute value.
-      def write_attribute_with_dirty(attr, value)
-        attr = attr.to_s
-
-        # The attribute already has an unsaved change.
-        if changed_attributes.include?(attr)
-          old = changed_attributes[attr]
-          changed_attributes.delete(attr) unless field_changed?(attr, old, value)
-        else
-          old = clone_attribute_value(:read_attribute, attr)
-          changed_attributes[attr] = old if field_changed?(attr, old, value)
-        end
-
-        # Carry on.
-        write_attribute_without_dirty(attr, value)
-      end
-
-      def update_with_dirty
-        if partial_updates?
-          # Serialized attributes should always be written in case they've been
-          # changed in place.
-          update_without_dirty(changed | self.class.serialized_attributes.keys)
-        else
-          update_without_dirty
-        end
-      end
-
-      def field_changed?(attr, old, value)
-        if column = column_for_attribute(attr)
-          if column.number? && column.null && (old.nil? || old == 0) && value.blank?
-            # For nullable numeric columns, NULL gets stored in database for blank (i.e. '') values.
-            # Hence we don't record it as a change if the value changes from nil to ''.
-            # If an old value of 0 is set to '' we want this to get changed to nil as otherwise it'll
-            # be typecast back to 0 (''.to_i => 0)
-            value = nil
-          else
-            value = column.type_cast(value)
-          end
-        end
-
-        old != value
-      end
-
-    module ClassMethods
-      def self.extended(base)
-        class << base
-          alias_method_chain :alias_attribute, :dirty
-        end
-      end
-
-      def alias_attribute_with_dirty(new_name, old_name)
-        alias_attribute_without_dirty(new_name, old_name)
-        DIRTY_SUFFIXES.each do |suffix|
-          module_eval <<-STR, __FILE__, __LINE__+1
-            def #{new_name}#{suffix}; self.#{old_name}#{suffix}; end  # def subject_changed?; self.title_changed?; end
-          STR
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 3963baa6b8..adb3a3f75e 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -388,13 +388,11 @@ module ActiveRecord
       end
 
       def rollback(migrations_path, steps=1)
-        migrator = self.new(:down, migrations_path)
-        start_index = migrator.migrations.index(migrator.current_migration)
-        
-        return unless start_index
-        
-        finish = migrator.migrations[start_index + steps]
-        down(migrations_path, finish ? finish.version : 0)
+        move(:down, migrations_path, steps)
+      end
+
+      def forward(migrations_path, steps=1)
+        move(:up, migrations_path, steps)
       end
 
       def up(migrations_path, target_version = nil)
@@ -430,6 +428,19 @@ module ActiveRecord
         # Use the Active Record objects own table_name, or pre/suffix from ActiveRecord::Base if name is a symbol/string
         name.table_name rescue "#{ActiveRecord::Base.table_name_prefix}#{name}#{ActiveRecord::Base.table_name_suffix}"
       end
+
+      private
+
+      def move(direction, migrations_path, steps)
+        migrator = self.new(direction, migrations_path)
+        start_index = migrator.migrations.index(migrator.current_migration)
+
+        if start_index
+          finish = migrator.migrations[start_index + steps]
+          version = finish ? finish.version : 0
+          send(direction, migrations_path, version)
+        end
+      end
     end
 
     def initialize(direction, migrations_path, target_version = nil)
diff --git a/activerecord/lib/active_record/schema_dumper.rb b/activerecord/lib/active_record/schema_dumper.rb
index 5d88012e4f..c8e1b4f53a 100644
--- a/activerecord/lib/active_record/schema_dumper.rb
+++ b/activerecord/lib/active_record/schema_dumper.rb
@@ -84,7 +84,6 @@ HEADER
           elsif @connection.respond_to?(:primary_key)
             pk = @connection.primary_key(table)
           end
-          pk ||= 'id'
           
           tbl.print "  create_table #{table.inspect}"
           if columns.detect { |c| c.name == pk }
diff --git a/activerecord/lib/active_record/state_machine.rb b/activerecord/lib/active_record/state_machine.rb
new file mode 100644
index 0000000000..aebd03344a
--- /dev/null
+++ b/activerecord/lib/active_record/state_machine.rb
@@ -0,0 +1,24 @@
+module ActiveRecord
+  module StateMachine #:nodoc:
+    extend ActiveSupport::Concern
+    include ActiveModel::StateMachine
+
+    included do
+      before_validation :set_initial_state
+      validates_presence_of :state
+    end
+
+    protected
+      def write_state(state_machine, state)
+        update_attributes! :state => state.to_s
+      end
+
+      def read_state(state_machine)
+        self.state.to_sym
+      end
+
+      def set_initial_state
+        self.state ||= self.class.state_machine.initial_state.to_s
+      end
+  end
+end