From 089cdfc05fe5a9340627bb87c48f9e123a18dde9 Mon Sep 17 00:00:00 2001
From: Eric Chapweske <eric@chapweske.com>
Date: Fri, 16 Oct 2009 18:09:17 -0700
Subject: [PATCH] Refactoring attributes/types

---
 activerecord/lib/active_record.rb                  |   16 +++
 .../attribute_methods/before_type_cast.rb          |   13 +--
 .../lib/active_record/attribute_methods/query.rb   |   20 +---
 .../lib/active_record/attribute_methods/read.rb    |   49 +--------
 .../attribute_methods/time_zone_conversion.rb      |   48 ++-------
 .../lib/active_record/attribute_methods/write.rb   |    9 +-
 activerecord/lib/active_record/attributes.rb       |   37 ++++++
 .../lib/active_record/attributes/aliasing.rb       |   42 +++++++
 activerecord/lib/active_record/attributes/store.rb |   15 +++
 .../lib/active_record/attributes/typecasting.rb    |  111 ++++++++++++++++++
 activerecord/lib/active_record/base.rb             |   38 +-----
 activerecord/lib/active_record/types.rb            |   38 +++++++
 activerecord/lib/active_record/types/number.rb     |   30 +++++
 activerecord/lib/active_record/types/object.rb     |   37 ++++++
 activerecord/lib/active_record/types/serialize.rb  |   33 ++++++
 .../lib/active_record/types/time_with_zone.rb      |   20 ++++
 activerecord/lib/active_record/types/unknown.rb    |   37 ++++++
 .../test/cases/attributes/aliasing_test.rb         |   20 ++++
 .../test/cases/attributes/typecasting_test.rb      |  118 ++++++++++++++++++++
 activerecord/test/cases/types/number_test.rb       |   30 +++++
 activerecord/test/cases/types/object_test.rb       |   24 ++++
 activerecord/test/cases/types/serialize_test.rb    |   20 ++++
 .../test/cases/types/time_with_zone_test.rb        |   42 +++++++
 activerecord/test/cases/types/unknown_test.rb      |   29 +++++
 activerecord/test/cases/types_test.rb              |   32 ++++++
 25 files changed, 760 insertions(+), 148 deletions(-)
 create mode 100644 activerecord/lib/active_record/attributes.rb
 create mode 100644 activerecord/lib/active_record/attributes/aliasing.rb
 create mode 100644 activerecord/lib/active_record/attributes/store.rb
 create mode 100644 activerecord/lib/active_record/attributes/typecasting.rb
 create mode 100644 activerecord/lib/active_record/types.rb
 create mode 100644 activerecord/lib/active_record/types/number.rb
 create mode 100644 activerecord/lib/active_record/types/object.rb
 create mode 100644 activerecord/lib/active_record/types/serialize.rb
 create mode 100644 activerecord/lib/active_record/types/time_with_zone.rb
 create mode 100644 activerecord/lib/active_record/types/unknown.rb
 create mode 100644 activerecord/test/cases/attributes/aliasing_test.rb
 create mode 100644 activerecord/test/cases/attributes/typecasting_test.rb
 create mode 100644 activerecord/test/cases/types/number_test.rb
 create mode 100644 activerecord/test/cases/types/object_test.rb
 create mode 100644 activerecord/test/cases/types/serialize_test.rb
 create mode 100644 activerecord/test/cases/types/time_with_zone_test.rb
 create mode 100644 activerecord/test/cases/types/unknown_test.rb
 create mode 100644 activerecord/test/cases/types_test.rb

diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index 2d66fa9..8f118a6 100644
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -51,6 +51,7 @@ module ActiveRecord
   autoload :AssociationPreload, 'active_record/association_preload'
   autoload :Associations, 'active_record/associations'
   autoload :AttributeMethods, 'active_record/attribute_methods'
+  autoload :Attributes, 'active_record/attributes'
   autoload :AutosaveAssociation, 'active_record/autosave_association'
   autoload :Relation, 'active_record/relation'
   autoload :Base, 'active_record/base'
@@ -74,6 +75,7 @@ module ActiveRecord
   autoload :TestCase, 'active_record/test_case'
   autoload :Timestamp, 'active_record/timestamp'
   autoload :Transactions, 'active_record/transactions'
+  autoload :Types, 'active_record/types'
   autoload :Validator, 'active_record/validator'
   autoload :Validations, 'active_record/validations'
 
@@ -87,6 +89,20 @@ module ActiveRecord
     autoload :Write, 'active_record/attribute_methods/write'
   end
 
+  module Attributes
+    autoload :Aliasing, 'active_record/attributes/aliasing'
+    autoload :Store, 'active_record/attributes/store'
+    autoload :Typecasting, 'active_record/attributes/typecasting'
+  end
+
+  module Type
+    autoload :Number, 'active_record/types/number'
+    autoload :Object, 'active_record/types/object'
+    autoload :Serialize, 'active_record/types/serialize'
+    autoload :TimeWithZone, 'active_record/types/time_with_zone'
+    autoload :Unknown, 'active_record/types/unknown'
+  end
+
   module Locking
     autoload :Optimistic, 'active_record/locking/optimistic'
     autoload :Pessimistic, 'active_record/locking/pessimistic'
diff --git a/activerecord/lib/active_record/attribute_methods/before_type_cast.rb b/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
index a4e144f..7492124 100644
--- a/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
+++ b/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
@@ -8,25 +8,18 @@ module ActiveRecord
       end
 
       def read_attribute_before_type_cast(attr_name)
-        @attributes[attr_name]
+        _attributes.without_typecast[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
+        _attributes.without_typecast
       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
+          read_attribute_before_type_cast(attribute_name)
         end
     end
   end
diff --git a/activerecord/lib/active_record/attribute_methods/query.rb b/activerecord/lib/active_record/attribute_methods/query.rb
index a949d80..0154ee3 100644
--- a/activerecord/lib/active_record/attribute_methods/query.rb
+++ b/activerecord/lib/active_record/attribute_methods/query.rb
@@ -8,23 +8,7 @@ module ActiveRecord
       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
+        _attributes.has?(attr_name)
       end
 
       private
@@ -35,3 +19,5 @@ module ActiveRecord
     end
   end
 end
+
+
diff --git a/activerecord/lib/active_record/attribute_methods/read.rb b/activerecord/lib/active_record/attribute_methods/read.rb
index 3da3d9d..97caec7 100644
--- a/activerecord/lib/active_record/attribute_methods/read.rb
+++ b/activerecord/lib/active_record/attribute_methods/read.rb
@@ -37,11 +37,7 @@ module ActiveRecord
 
         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
+            define_read_method(attr_name.to_sym, attr_name, columns_hash[attr_name])
 
             if attr_name == primary_key && attr_name != "id"
               define_read_method(:id, attr_name, columns_hash[attr_name])
@@ -49,18 +45,12 @@ module ActiveRecord
           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}']"
-
+            access_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}'); ")
+              access_code = access_code.insert(0, "missing_attribute('#{attr_name}', caller) unless _attributes.key?('#{attr_name}'); ")
             end
 
             if cache_attribute?(attr_name)
@@ -73,38 +63,7 @@ module ActiveRecord
       # 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
+        _attributes[attr_name]
       end
 
       private
diff --git a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
index a8e3e28..4ac0c7f 100644
--- a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
+++ b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
@@ -12,48 +12,20 @@ module ActiveRecord
       end
 
       module ClassMethods
+
+        def cache_attribute?(attr_name)
+          time_zone_aware?(attr_name) || super
+        end
+
         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
+          def time_zone_aware?(attr_name)
+            column = columns_hash[attr_name]
+            time_zone_aware_attributes &&
+              !skip_time_zone_conversion_for_attributes.include?(attr_name.to_sym) &&
+                [:datetime, :timestamp].include?(column.type)
           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
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index e31acac..37eadbe 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -17,14 +17,9 @@ module ActiveRecord
       # 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'
+        attr_name = _attributes.unalias(attr_name)
         @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
+        _attributes[attr_name] = value
       end
 
       private
diff --git a/activerecord/lib/active_record/attributes.rb b/activerecord/lib/active_record/attributes.rb
new file mode 100644
index 0000000..e4d9e89
--- /dev/null
+++ b/activerecord/lib/active_record/attributes.rb
@@ -0,0 +1,37 @@
+module ActiveRecord
+  module Attributes
+
+     # Returns true if the given attribute is in the attributes hash
+     def has_attribute?(attr_name)
+       _attributes.key?(attr_name)
+     end
+
+     # Returns an array of names for the attributes available on this object sorted alphabetically.
+     def attribute_names
+       _attributes.keys.sort!
+     end
+
+     # Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
+     def attributes
+       attributes = _attributes.dup
+       attributes.typecast! unless _attributes.frozen?
+       attributes.to_h
+     end
+
+     protected
+
+     # Not to be confused with the public #attributes method, which returns a typecasted Hash.
+     def _attributes
+       @attributes
+     end
+
+     def initialize_attribute_store(merge_attributes = nil)
+       @attributes = ActiveRecord::Attributes::Store.new
+       @attributes.merge!(merge_attributes) if merge_attributes
+       @attributes.types.merge!(self.class.attribute_types)
+       @attributes.aliases.merge!('id' => self.class.primary_key) unless 'id' == self.class.primary_key
+       @attributes
+     end
+
+  end
+end
diff --git a/activerecord/lib/active_record/attributes/aliasing.rb b/activerecord/lib/active_record/attributes/aliasing.rb
new file mode 100644
index 0000000..db77739
--- /dev/null
+++ b/activerecord/lib/active_record/attributes/aliasing.rb
@@ -0,0 +1,42 @@
+module ActiveRecord
+  module Attributes
+    module Aliasing
+      # Allows access to keys using aliased names.
+      #
+      # Example:
+      # class Attributes < Hash
+      #   include Aliasing
+      # end
+      #
+      # attributes = Attributes.new
+      # attributes.aliases['id'] = 'fancy_primary_key'
+      # attributes['fancy_primary_key'] = 2020
+      #
+      # attributes['id']
+      # => 2020
+      #
+      # Additionally, symbols are always aliases of strings:
+      # attributes[:fancy_primary_key]
+      # => 2020
+      #
+      def [](key)
+        super(unalias(key))
+      end
+
+      def []=(key, value)
+        super(unalias(key), value)
+      end
+
+      def aliases
+        @aliases ||= {}
+      end
+
+      def unalias(key)
+        key = key.to_s
+        aliases[key] || key
+      end
+
+    end
+  end
+end
+
diff --git a/activerecord/lib/active_record/attributes/store.rb b/activerecord/lib/active_record/attributes/store.rb
new file mode 100644
index 0000000..61109f4
--- /dev/null
+++ b/activerecord/lib/active_record/attributes/store.rb
@@ -0,0 +1,15 @@
+module ActiveRecord
+  module Attributes
+    class Store < Hash
+      include ActiveRecord::Attributes::Typecasting
+      include ActiveRecord::Attributes::Aliasing
+
+      # Attributes not mapped to a column are handled using Type::Unknown,
+      # which enables boolean typecasting for unmapped keys.
+      def types
+        @types ||= Hash.new(Type::Unknown.new)
+      end
+
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/attributes/typecasting.rb b/activerecord/lib/active_record/attributes/typecasting.rb
new file mode 100644
index 0000000..de36a29
--- /dev/null
+++ b/activerecord/lib/active_record/attributes/typecasting.rb
@@ -0,0 +1,111 @@
+module ActiveRecord
+  module Attributes
+    module Typecasting
+      # Typecasts values during access based on their key mapping to a Type.
+      #
+      # Example:
+      # class Attributes < Hash
+      #   include Typecasting
+      # end
+      #
+      # attributes = Attributes.new
+      # attributes.types['comments_count'] = Type::Integer
+      # attributes['comments_count'] = '5'
+      #
+      # attributes['comments_count']
+      # => 5
+      #
+      # To support keys not mapped to a typecaster, add a default to types.
+      # attributes.types.default = Type::Unknown
+      # attributes['age'] = '25'
+      # attributes['age']
+      # => '25'
+      #
+      # A valid type supports #cast, #precast, #boolean, and #appendable? methods.
+      #
+      def [](key)
+        value = super(key)
+        typecast_read(key, value)
+      end
+
+      def []=(key, value)
+        super(key, typecast_write(key, value))
+      end
+
+      def to_h
+        hash = {}
+        hash.merge!(self)
+        hash
+      end
+
+      # Provides a duplicate with typecasting disabled.
+      #
+      # Example:
+      # attributes = Attributes.new
+      # attributes.types['comments_count'] = Type::Integer
+      # attributes['comments_count'] = '5'
+      #
+      # attributes.without_typecast['comments_count']
+      # => '5'
+      #
+      def without_typecast
+        dup.without_typecast!
+      end
+
+      def without_typecast!
+        types.clear
+        self
+      end
+
+      def typecast!
+        keys.each { |key| self[key] = self[key] }
+        self
+      end
+
+      # Check if key has a value that typecasts to true.
+      #
+      # attributes = Attributes.new
+      # attributes.types['comments_count'] = Type::Integer
+      #
+      # attributes['comments_count'] = 0
+      # attributes.has?('comments_count')
+      # => false
+      #
+      # attributes['comments_count'] = 1
+      # attributes.has?('comments_count')
+      # => true
+      #
+      def has?(key)
+        value = self[key]
+        boolean_typecast(key, value)
+      end
+
+      def types
+        @types ||= {}
+      end
+
+      protected
+
+      def types=(other_types)
+        @types = other_types
+      end
+
+      def boolean_typecast(key, value)
+        value ? types[key].boolean(value) : false
+      end
+
+      def typecast_read(key, value)
+        type  = types[key]
+        value = type.cast(value)
+        self[key] = value if type.appendable? && !frozen?
+
+        value
+      end
+
+      def typecast_write(key, value)
+        types[key].precast(value)
+      end
+
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 76dbd00..4274df5 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -1644,7 +1644,7 @@ module ActiveRecord #:nodoc:
         def instantiate(record)
           object = find_sti_class(record[inheritance_column]).allocate
 
-          object.instance_variable_set(:'@attributes', record)
+          object.send(:initialize_attribute_store, record)
           object.instance_variable_set(:'@attributes_cache', {})
 
           object.send(:_run_find_callbacks)
@@ -2415,7 +2415,7 @@ module ActiveRecord #:nodoc:
       # In both instances, valid attribute keys are determined by the column names of the associated table --
       # hence you can't have attributes that aren't part of the table columns.
       def initialize(attributes = nil)
-        @attributes = attributes_from_column_definition
+        initialize_attribute_store(attributes_from_column_definition)
         @attributes_cache = {}
         @new_record = true
         ensure_proper_type
@@ -2441,7 +2441,7 @@ module ActiveRecord #:nodoc:
         callback(:after_initialize) if respond_to_without_attributes?(:after_initialize)
         cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
         cloned_attributes.delete(self.class.primary_key)
-        @attributes = cloned_attributes
+        initialize_attribute_store(cloned_attributes)
         clear_aggregation_cache
         @attributes_cache = {}
         @new_record = true
@@ -2667,7 +2667,7 @@ module ActiveRecord #:nodoc:
       def reload(options = nil)
         clear_aggregation_cache
         clear_association_cache
-        @attributes.update(self.class.find(self.id, options).instance_variable_get('@attributes'))
+        _attributes.update(self.class.find(self.id, options).instance_variable_get('@attributes'))
         @attributes_cache = {}
         self
       end
@@ -2764,16 +2764,6 @@ module ActiveRecord #:nodoc:
         !value.blank?
       end
 
-      # Returns true if the given attribute is in the attributes hash
-      def has_attribute?(attr_name)
-        @attributes.has_key?(attr_name.to_s)
-      end
-
-      # Returns an array of names for the attributes available on this object sorted alphabetically.
-      def attribute_names
-        @attributes.keys.sort
-      end
-
       # Returns the column object for the named attribute.
       def column_for_attribute(name)
         self.class.columns_hash[name.to_s]
@@ -2897,18 +2887,6 @@ module ActiveRecord #:nodoc:
         end
       end
 
-      def convert_number_column_value(value)
-        if value == false
-          0
-        elsif value == true
-          1
-        elsif value.is_a?(String) && value.blank?
-          nil
-        else
-          value
-        end
-      end
-
       def remove_attributes_protected_from_mass_assignment(attributes)
         safe_attributes =
           if self.class.accessible_attributes.nil? && self.class.protected_attributes.nil?
@@ -3027,7 +3005,7 @@ module ActiveRecord #:nodoc:
       end
 
       def instantiate_time_object(name, values)
-        if self.class.send(:create_time_zone_conversion_attribute?, name, column_for_attribute(name))
+        if self.class.send(:time_zone_aware?, name)
           Time.zone.local(*values)
         else
           Time.time_with_datetime_fallback(@@default_timezone, *values)
@@ -3114,10 +3092,6 @@ module ActiveRecord #:nodoc:
         comma_pair_list(quote_columns(quoter, hash))
       end
 
-      def object_from_yaml(string)
-        return string unless string.is_a?(String) && string =~ /^---/
-        YAML::load(string) rescue string
-      end
   end
 
   Base.class_eval do
@@ -3132,6 +3106,7 @@ module ActiveRecord #:nodoc:
     include AttributeMethods::PrimaryKey
     include AttributeMethods::TimeZoneConversion
     include AttributeMethods::Dirty
+    include Attributes, Types
     include Callbacks, ActiveModel::Observing, Timestamp
     include Associations, AssociationPreload, NamedScope
     include ActiveModel::Conversion
@@ -3141,6 +3116,7 @@ module ActiveRecord #:nodoc:
     include AutosaveAssociation, NestedAttributes
 
     include Aggregations, Transactions, Reflection, Batches, Calculations, Serialization
+
   end
 end
 
diff --git a/activerecord/lib/active_record/types.rb b/activerecord/lib/active_record/types.rb
new file mode 100644
index 0000000..74f5693
--- /dev/null
+++ b/activerecord/lib/active_record/types.rb
@@ -0,0 +1,38 @@
+module ActiveRecord
+  module Types
+    extend ActiveSupport::Concern
+
+    module ClassMethods
+
+      def attribute_types
+        attribute_types = {}
+        columns.each do |column|
+          options = {}
+          options[:time_zone_aware] = time_zone_aware?(column.name)
+          options[:serialize]       = serialized_attributes[column.name]
+
+          attribute_types[column.name] = to_type(column, options)
+        end
+        attribute_types
+      end
+
+      private
+
+      def to_type(column, options = {})
+        type_class = if options[:time_zone_aware]
+          Type::TimeWithZone
+        elsif options[:serialize]
+          Type::Serialize
+        elsif [ :integer, :float, :decimal ].include?(column.type)
+          Type::Number
+        else
+          Type::Object
+        end
+
+        type_class.new(column, options)
+      end
+
+    end
+
+  end
+end
diff --git a/activerecord/lib/active_record/types/number.rb b/activerecord/lib/active_record/types/number.rb
new file mode 100644
index 0000000..cfbe877
--- /dev/null
+++ b/activerecord/lib/active_record/types/number.rb
@@ -0,0 +1,30 @@
+module ActiveRecord
+  module Type
+    class Number < Object
+
+      def boolean(value)
+        value = cast(value)
+        !(value.nil? || value.zero?)
+      end
+
+      def precast(value)
+        convert_number_column_value(value)
+      end
+
+      private
+
+      def convert_number_column_value(value)
+        if value == false
+          0
+        elsif value == true
+          1
+        elsif value.is_a?(String) && value.blank?
+          nil
+        else
+          value
+        end
+      end
+
+    end
+  end
+end
\ No newline at end of file
diff --git a/activerecord/lib/active_record/types/object.rb b/activerecord/lib/active_record/types/object.rb
new file mode 100644
index 0000000..ec3f861
--- /dev/null
+++ b/activerecord/lib/active_record/types/object.rb
@@ -0,0 +1,37 @@
+module ActiveRecord
+  module Type
+    module Casting
+
+       def cast(value)
+         typecaster.type_cast(value)
+       end
+
+       def precast(value)
+         value
+       end
+
+       def boolean(value)
+         cast(value).present?
+       end
+
+       # Attributes::Typecasting stores appendable? types (e.g. serialized Arrays) when typecasting reads.
+       def appendable?
+         false
+       end
+
+    end
+
+    class Object
+      include Casting
+
+      attr_reader :name, :options
+      attr_reader :typecaster
+
+      def initialize(typecaster = nil, options = {})
+        @typecaster, @options = typecaster, options
+      end
+
+    end
+
+  end
+end
\ No newline at end of file
diff --git a/activerecord/lib/active_record/types/serialize.rb b/activerecord/lib/active_record/types/serialize.rb
new file mode 100644
index 0000000..7b6af19
--- /dev/null
+++ b/activerecord/lib/active_record/types/serialize.rb
@@ -0,0 +1,33 @@
+module ActiveRecord
+  module Type
+    class Serialize < Object
+
+      def cast(value)
+        unserialize(value)
+      end
+
+      def appendable?
+        true
+      end
+
+      protected
+
+      def unserialize(value)
+        unserialized_object = object_from_yaml(value)
+
+        if unserialized_object.is_a?(@options[:serialize]) || unserialized_object.nil?
+          unserialized_object
+        else
+          raise SerializationTypeMismatch,
+            "#{name} was supposed to be a #{@options[:serialize]}, but was a #{unserialized_object.class.to_s}"
+        end
+      end
+
+      def object_from_yaml(string)
+        return string unless string.is_a?(String) && string =~ /^---/
+        YAML::load(string) rescue string
+      end
+
+    end
+  end
+end
\ No newline at end of file
diff --git a/activerecord/lib/active_record/types/time_with_zone.rb b/activerecord/lib/active_record/types/time_with_zone.rb
new file mode 100644
index 0000000..3a8b929
--- /dev/null
+++ b/activerecord/lib/active_record/types/time_with_zone.rb
@@ -0,0 +1,20 @@
+module ActiveRecord
+  module Type
+    class TimeWithZone < Object
+
+      def cast(time)
+        time = super(time)
+        time.acts_like?(:time) ? time.in_time_zone : time
+      end
+
+      def precast(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
+        super(time)
+      end
+
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/types/unknown.rb b/activerecord/lib/active_record/types/unknown.rb
new file mode 100644
index 0000000..f832c7b
--- /dev/null
+++ b/activerecord/lib/active_record/types/unknown.rb
@@ -0,0 +1,37 @@
+module ActiveRecord
+  module Type
+    # Useful for handling attributes not mapped to types. Performs some boolean typecasting,
+    # but otherwise leaves the value untouched.
+    class Unknown
+
+      def cast(value)
+        value
+      end
+
+      def precast(value)
+        value
+      end
+
+      # Attempts typecasting to handle numeric, false and blank values.
+      def boolean(value)
+        empty = (numeric?(value) && value.to_i.zero?) || false?(value) || value.blank?
+        !empty
+      end
+
+      def appendable?
+        false
+      end
+
+      protected
+
+      def false?(value)
+        ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES.include?(value)
+      end
+
+      def numeric?(value)
+        Numeric === value || value !~ /[^0-9]/
+      end
+
+    end
+  end
+end
\ No newline at end of file
diff --git a/activerecord/test/cases/attributes/aliasing_test.rb b/activerecord/test/cases/attributes/aliasing_test.rb
new file mode 100644
index 0000000..7ee2577
--- /dev/null
+++ b/activerecord/test/cases/attributes/aliasing_test.rb
@@ -0,0 +1,20 @@
+require "cases/helper"
+
+class AliasingTest < ActiveRecord::TestCase
+
+  class AliasingAttributes < Hash
+    include ActiveRecord::Attributes::Aliasing
+  end
+
+  test "attribute access with aliasing" do
+    attributes = AliasingAttributes.new
+    attributes[:name] = 'Batman'
+    attributes.aliases['nickname'] = 'name'
+
+    assert_equal 'Batman', attributes[:name], "Symbols should point to Strings"
+    assert_equal 'Batman', attributes['name']
+    assert_equal 'Batman', attributes['nickname']
+    assert_equal 'Batman', attributes[:nickname]
+  end
+
+end
diff --git a/activerecord/test/cases/attributes/typecasting_test.rb b/activerecord/test/cases/attributes/typecasting_test.rb
new file mode 100644
index 0000000..c712f22
--- /dev/null
+++ b/activerecord/test/cases/attributes/typecasting_test.rb
@@ -0,0 +1,118 @@
+require "cases/helper"
+
+class TypecastingTest < ActiveRecord::TestCase
+
+  class TypecastingAttributes < Hash
+    include ActiveRecord::Attributes::Typecasting
+  end
+
+  module MockType
+    class Object
+
+      def cast(value)
+        value
+      end
+
+      def precast(value)
+        value
+      end
+
+      def boolean(value)
+        !value.blank?
+      end
+
+      def appendable?
+        false
+      end
+
+    end
+
+    class Integer < Object
+
+      def cast(value)
+        value.to_i
+      end
+
+      def precast(value)
+        value ? value : 0
+      end
+
+      def boolean(value)
+        !Float(value).zero?
+      end
+
+    end
+
+    class Serialize < Object
+
+      def cast(value)
+        YAML::load(value) rescue value
+      end
+
+      def precast(value)
+        value
+      end
+
+      def appendable?
+        true
+      end
+
+    end
+  end
+
+  def setup
+    @attributes = TypecastingAttributes.new
+    @attributes.types.default = MockType::Object.new
+    @attributes.types['comments_count'] = MockType::Integer.new
+  end
+
+  test "typecast on read" do
+    attributes = @attributes.merge('comments_count' => '5')
+    assert_equal 5, attributes['comments_count']
+  end
+
+  test "typecast on write" do
+    @attributes['comments_count'] = false
+
+    assert_equal 0, @attributes.to_h['comments_count']
+  end
+
+  test "serialized objects" do
+    attributes = @attributes.merge('tags' => [ 'peanut butter' ].to_yaml)
+    attributes.types['tags'] = MockType::Serialize.new
+    attributes['tags'] << 'jelly'
+
+    assert_equal [ 'peanut butter', 'jelly' ], attributes['tags']
+  end
+
+  test "without typecasting" do
+    attributes = @attributes.without_typecast
+    attributes['comments_count'] = '5'
+
+    assert_equal '5', attributes['comments_count']
+  end
+
+  test "typecast all attributes" do
+    attributes = @attributes.merge('title' => 'I love sandwiches', 'comments_count' => '5')
+    attributes.typecast!
+
+    assert_equal({ 'title' => 'I love sandwiches', 'comments_count' => 5 }, attributes)
+  end
+
+  test "query for has? value" do
+    attributes = @attributes.merge('comments_count' => '1')
+
+    assert_equal true,  attributes.has?('comments_count')
+    attributes['comments_count'] = '0'
+    assert_equal false,  attributes.has?('comments_count')
+  end
+
+  test "attributes to Hash" do
+    attributes_hash = { 'title' => 'I love sandwiches', 'comments_count' => '5' }
+    attributes = @attributes.merge(attributes_hash)
+
+    assert_equal Hash, attributes.to_h.class
+    assert_equal attributes_hash, attributes.to_h
+  end
+
+end
diff --git a/activerecord/test/cases/types/number_test.rb b/activerecord/test/cases/types/number_test.rb
new file mode 100644
index 0000000..ee7216a
--- /dev/null
+++ b/activerecord/test/cases/types/number_test.rb
@@ -0,0 +1,30 @@
+require "cases/helper"
+
+class NumberTest < ActiveRecord::TestCase
+
+  def setup
+    @column = ActiveRecord::ConnectionAdapters::Column.new('comments_count', 0, 'integer')
+    @number = ActiveRecord::Type::Number.new(@column)
+  end
+
+  test "typecast" do
+    assert_equal 1, @number.cast(1)
+    assert_equal 1, @number.cast('1')
+    assert_equal 0, @number.cast('')
+
+    assert_equal 0,   @number.precast(false)
+    assert_equal 1,   @number.precast(true)
+    assert_equal nil, @number.precast('')
+    assert_equal 0,   @number.precast(0)
+  end
+
+  test "cast as boolean" do
+    assert_equal true, @number.boolean('1')
+    assert_equal true, @number.boolean(1)
+
+    assert_equal false, @number.boolean(0)
+    assert_equal false, @number.boolean('0')
+    assert_equal false, @number.boolean(nil)
+  end
+
+end
diff --git a/activerecord/test/cases/types/object_test.rb b/activerecord/test/cases/types/object_test.rb
new file mode 100644
index 0000000..f2667a9
--- /dev/null
+++ b/activerecord/test/cases/types/object_test.rb
@@ -0,0 +1,24 @@
+require "cases/helper"
+
+class ObjectTest < ActiveRecord::TestCase
+
+  def setup
+    @column = ActiveRecord::ConnectionAdapters::Column.new('name', '', 'date')
+    @object = ActiveRecord::Type::Object.new(@column)
+  end
+
+  test "typecast with column" do
+    date = Date.new(2009, 7, 10)
+    assert_equal date, @object.cast('10-07-2009')
+    assert_equal nil,  @object.cast('')
+
+    assert_equal date, @object.precast(date)
+  end
+
+  test "cast as boolean" do
+    assert_equal false, @object.boolean(nil)
+    assert_equal false, @object.boolean('false')
+    assert_equal true,  @object.boolean('10-07-2009')
+  end
+
+end
diff --git a/activerecord/test/cases/types/serialize_test.rb b/activerecord/test/cases/types/serialize_test.rb
new file mode 100644
index 0000000..e9423a5
--- /dev/null
+++ b/activerecord/test/cases/types/serialize_test.rb
@@ -0,0 +1,20 @@
+require "cases/helper"
+
+class SerializeTest < ActiveRecord::TestCase
+
+  test "typecast" do
+    serializer = ActiveRecord::Type::Serialize.new(column = nil, :serialize => Array)
+
+    assert_equal [],    serializer.cast([].to_yaml)
+    assert_equal ['1'], serializer.cast(['1'].to_yaml)
+    assert_equal nil,   serializer.cast(nil.to_yaml)
+  end
+
+  test "cast as boolean" do
+    serializer = ActiveRecord::Type::Serialize.new(column = nil, :serialize => Array)
+
+    assert_equal true,  serializer.boolean(['1'].to_yaml)
+    assert_equal false, serializer.boolean([].to_yaml)
+  end
+
+end
\ No newline at end of file
diff --git a/activerecord/test/cases/types/time_with_zone_test.rb b/activerecord/test/cases/types/time_with_zone_test.rb
new file mode 100644
index 0000000..1bc5b40
--- /dev/null
+++ b/activerecord/test/cases/types/time_with_zone_test.rb
@@ -0,0 +1,42 @@
+require "cases/helper"
+
+class TimeWithZoneTest < ActiveRecord::TestCase
+
+  def setup
+    @column = ActiveRecord::ConnectionAdapters::Column.new('created_at', 0, 'datetime')
+    @time_with_zone = ActiveRecord::Type::TimeWithZone.new(@column)
+  end
+
+  test "typecast" do
+    Time.use_zone("Pacific Time (US & Canada)") do
+      time_string = "2009-10-07 21:29:10"
+      time = Time.zone.parse(time_string)
+
+      assert_equal time, @time_with_zone.cast(time_string)
+      assert_equal nil, @time_with_zone.cast('')
+      assert_equal nil, @time_with_zone.cast(nil)
+
+      assert_equal time, @time_with_zone.precast(time)
+      assert_equal time, @time_with_zone.precast(time_string)
+      assert_equal time, @time_with_zone.precast(time.to_time)
+      assert_equal "#{time.to_date.to_s} 00:00:00 -0700", @time_with_zone.precast(time.to_date).to_s
+    end
+  end
+
+  test "cast as boolean" do
+    Time.use_zone('Central Time (US & Canada)') do
+      time = Time.zone.now
+
+      assert_equal true, @time_with_zone.boolean(time)
+      assert_equal true, @time_with_zone.boolean(time.to_date)
+      assert_equal true, @time_with_zone.boolean(time.to_time)
+
+      assert_equal true, @time_with_zone.boolean(time.to_s)
+      assert_equal true, @time_with_zone.boolean(time.to_date.to_s)
+      assert_equal true, @time_with_zone.boolean(time.to_time.to_s)
+
+      assert_equal false, @time_with_zone.boolean('')
+    end
+  end
+
+end
diff --git a/activerecord/test/cases/types/unknown_test.rb b/activerecord/test/cases/types/unknown_test.rb
new file mode 100644
index 0000000..230d67b
--- /dev/null
+++ b/activerecord/test/cases/types/unknown_test.rb
@@ -0,0 +1,29 @@
+require "cases/helper"
+
+class UnknownTest < ActiveRecord::TestCase
+
+  test "typecast attributes does't modify values" do
+    unkown = ActiveRecord::Type::Unknown.new
+    person = { 'name' => '0' }
+
+    assert_equal person['name'], unkown.cast(person['name'])
+    assert_equal person['name'], unkown.precast(person['name'])
+  end
+
+  test "cast as boolean" do
+    person =  { 'id' => 0, 'name' => ' ', 'admin' => 'false', 'votes' => '0' }
+    unkown = ActiveRecord::Type::Unknown.new
+
+    assert_equal false, unkown.boolean(person['votes'])
+    assert_equal false, unkown.boolean(person['admin'])
+    assert_equal false, unkown.boolean(person['name'])
+    assert_equal false, unkown.boolean(person['id'])
+
+    person = { 'id' => 5, 'name' => 'Eric', 'admin' => 'true', 'votes' => '25' }
+    assert_equal true, unkown.boolean(person['votes'])
+    assert_equal true, unkown.boolean(person['admin'])
+    assert_equal true, unkown.boolean(person['name'])
+    assert_equal true, unkown.boolean(person['id'])
+  end
+
+end
\ No newline at end of file
diff --git a/activerecord/test/cases/types_test.rb b/activerecord/test/cases/types_test.rb
new file mode 100644
index 0000000..403a9a6
--- /dev/null
+++ b/activerecord/test/cases/types_test.rb
@@ -0,0 +1,32 @@
+require "cases/helper"
+require 'models/topic'
+
+class TypesTest < ActiveRecord::TestCase
+
+  test "attribute types from columns" do
+    begin
+    ActiveRecord::Base.time_zone_aware_attributes = true
+    attribute_type_classes = {}
+    Topic.attribute_types.each { |key, type| attribute_type_classes[key] = type.class }
+
+    expected = { "id"            => ActiveRecord::Type::Number,
+                  "replies_count" => ActiveRecord::Type::Number,
+                  "parent_id"     => ActiveRecord::Type::Number,
+                  "content"       => ActiveRecord::Type::Serialize,
+                  "written_on"    => ActiveRecord::Type::TimeWithZone,
+                  "title"         => ActiveRecord::Type::Object,
+                  "author_name"   => ActiveRecord::Type::Object,
+                  "approved"      => ActiveRecord::Type::Object,
+                  "parent_title"  => ActiveRecord::Type::Object,
+                  "bonus_time"    => ActiveRecord::Type::Object,
+                  "type"          => ActiveRecord::Type::Object,
+                  "last_read"     => ActiveRecord::Type::Object,
+                  "author_email_address" => ActiveRecord::Type::Object }
+
+    assert_equal expected, attribute_type_classes
+   ensure
+     ActiveRecord::Base.time_zone_aware_attributes = false
+   end
+  end
+
+end
-- 
1.6.4.4