Feature for field method, passing a type option will accepts any active record sql types and type casts the value when it is set.

Gemfile

@@ -6,6 +6,7 @@ gem 'rspec', '~> 2.2.0'
 gem 'wwtd'
 gem 'rake'
 gem 'json'
+gem 'virtus'
 
 platforms :jruby do
   gem 'activerecord-jdbcsqlite3-adapter', '>= 1.3.6'

gemfiles/rails_2.3.gemfile

@@ -5,6 +5,7 @@ gem 'rspec', '~> 2.2.0'
 gem 'wwtd'
 gem 'rake'
 gem 'json'
+gem 'virtus'
 
 platform :jruby do
   gem 'activerecord-jdbcsqlite3-adapter', '>= 1.3.6'

gemfiles/rails_3.0.gemfile

@@ -5,6 +5,7 @@ gem 'rspec', '~> 2.2.0'
 gem 'wwtd'
 gem 'rake'
 gem 'json'
+gem 'virtus'
 
 platform :jruby do
   gem 'activerecord-jdbcsqlite3-adapter', '>= 1.3.6'

gemfiles/rails_3.1.gemfile

@@ -5,6 +5,7 @@ gem 'rspec', '~> 2.2.0'
 gem 'wwtd'
 gem 'rake'
 gem 'json'
+gem 'virtus'
 
 platform :jruby do
   gem 'activerecord-jdbcsqlite3-adapter', '>= 1.3.6'

gemfiles/rails_3.2.gemfile

@@ -5,6 +5,7 @@ gem 'rspec', '~> 2.2.0'
 gem 'wwtd'
 gem 'rake'
 gem 'json'
+gem 'virtus'
 
 platform :jruby do
   gem 'activerecord-jdbcsqlite3-adapter', '>= 1.3.6'

gemfiles/rails_4.0.gemfile

@@ -5,6 +5,7 @@ gem 'rspec', '~> 2.2.0'
 gem 'wwtd'
 gem 'rake'
 gem 'json'
+gem 'virtus'
 
 platform :jruby do
   gem 'activerecord-jdbcsqlite3-adapter', '>= 1.3.6'

gemfiles/rails_edge.gemfile

@@ -6,6 +6,7 @@ gem 'rspec', '~> 2.2.0'
 gem 'wwtd'
 gem 'rake'
 gem 'json'
+gem 'virtus'
 
 platform :jruby do
   gem 'activerecord-jdbcsqlite3-adapter', '>= 1.3.6'

lib/active_hash.rb

@@ -20,3 +20,4 @@
 require 'active_json/base'
 require 'associations/associations'
 require 'enum/enum'
+require 'virtus'

lib/active_hash/base.rb

@@ -39,6 +39,14 @@ def field_names
         @field_names ||= []
       end
 
+      def types
+        @types ||= {}
+      end
+
+      def set_type(field_name, type)
+        types[field_name] = Virtus::Attribute.build(type)
+      end
+
       def the_meta_class
         class << self
           self
@@ -199,6 +207,7 @@ def field(field_name, options = {})
         validate_field(field_name)
         field_names << field_name
 
+        set_type(field_name, options[:type])
         define_getter_method(field_name, options[:default])
         define_setter_method(field_name)
         define_interrogator_method(field_name)
@@ -269,7 +278,7 @@ def define_setter_method(field)
         method_name = "#{field}="
         unless has_instance_method?(method_name)
           define_method(method_name) do |new_val|
-            attributes[field] = new_val
+            attributes[field] = coerce(field, new_val)
           end
         end
       end
@@ -374,7 +383,7 @@ def has_singleton_method?(name)
 
     end
 
-    attr_reader :attributes
+    attr_reader :attributes, :types
 
     def initialize(attributes = {})
       attributes.symbolize_keys!
@@ -470,5 +479,11 @@ def marked_for_destruction?
       false
     end
 
+    def coerce(field, new_val)
+      type = self.class.types[field]
+      return attributes[field] = type.coerce(new_val) unless type.nil?
+      return new_value
+    end
+
   end
 end

spec/active_hash/base_spec.rb

@@ -634,6 +634,41 @@ class Region < ActiveHash::Base
         country.name.should == "foobar"
       end
     end
+
+    context "for fields with type values" do
+
+      before do
+        Country.field :population, :type => 'Integer', :default => false
+      end
+
+      context "entered values will be converted to set type" do
+
+        it 'when pass to new' do
+          country = Country.new(:population => "500000")
+          country.population.should == 500000
+        end
+
+        it 'when pass to setter' do
+          country = Country.new
+          country.population = '500000'
+          country.population.should == 500000
+        end
+
+      end
+
+      context 'valid types, accepts Ruby types' do
+
+        before do
+          Country.field :independence_day, :type => 'Date', :default => false
+        end
+
+        it 'date' do
+          country = Country.new(:independence_day => "01/12/1934")
+          country.independence_day.class.should == Date
+        end
+      end
+
+    end
   end
 
   describe "interrogator methods" do