From 6c63f1aa44780c887dd3e52765e86588911c2802 Mon Sep 17 00:00:00 2001
From: Jon Leighton <j@jonathanleighton.com>
Date: Wed, 30 Nov 2011 16:00:19 +0000
Subject: Move some serialization stuff out of Base

---
 .../attribute_methods/serialization.rb             | 42 ++++++++++++++++++++++
 1 file changed, 42 insertions(+)

(limited to 'activerecord/lib/active_record/attribute_methods')

diff --git a/activerecord/lib/active_record/attribute_methods/serialization.rb b/activerecord/lib/active_record/attribute_methods/serialization.rb
index 686754fbc2..001620d889 100644
--- a/activerecord/lib/active_record/attribute_methods/serialization.rb
+++ b/activerecord/lib/active_record/attribute_methods/serialization.rb
@@ -3,7 +3,41 @@ module ActiveRecord
     module Serialization
       extend ActiveSupport::Concern
 
+      included do
+        # Returns a hash of all the attributes that have been specified for serialization as
+        # keys and their class restriction as values.
+        class_attribute :serialized_attributes
+        self.serialized_attributes = {}
+      end
+
       module ClassMethods
+        # If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object,
+        # then specify the name of that attribute using this method and it will be handled automatically.
+        # The serialization is done through YAML. If +class_name+ is specified, the serialized object must be of that
+        # class on retrieval or SerializationTypeMismatch will be raised.
+        #
+        # ==== Parameters
+        #
+        # * +attr_name+ - The field name that should be serialized.
+        # * +class_name+ - Optional, class name that the object type should be equal to.
+        #
+        # ==== Example
+        #   # Serialize a preferences attribute
+        #   class User < ActiveRecord::Base
+        #     serialize :preferences
+        #   end
+        def serialize(attr_name, class_name = Object)
+          coder = if [:load, :dump].all? { |x| class_name.respond_to?(x) }
+                    class_name
+                  else
+                    Coders::YAMLColumn.new(class_name)
+                  end
+
+          # merge new serialized attribute and create new hash to ensure that each class in inheritance hierarchy
+          # has its own hash of own serialized attributes
+          self.serialized_attributes = serialized_attributes.merge(attr_name.to_s => coder)
+        end
+
         def define_method_attribute(attr_name)
           if serialized_attributes.include?(attr_name)
             generated_attribute_methods.module_eval(<<-CODE, __FILE__, __LINE__)
@@ -22,6 +56,14 @@ module ActiveRecord
         end
       end
 
+      def set_serialized_attributes
+        sattrs = self.class.serialized_attributes
+
+        sattrs.each do |key, coder|
+          @attributes[key] = coder.load @attributes[key] if @attributes.key?(key)
+        end
+      end
+
       def type_cast_attribute(column, value)
         coder = self.class.serialized_attributes[column.name]
 
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