wrap and cache columns for typecasting

3 files changed, 30 insertions, 5 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/serialization.rb b/activerecord/lib/active_record/attribute_methods/serialization.rb
index 38e7bf77ef..3bc749dabf 100644
--- a/activerecord/lib/active_record/attribute_methods/serialization.rb
+++ b/activerecord/lib/active_record/attribute_methods/serialization.rb
@@ -10,6 +10,16 @@ module ActiveRecord
         self.serialized_attributes = {}
       end
 
+      class Type # :nodoc:
+        def initialize(column)
+          @column = column
+        end
+
+        def type_cast(value)
+          value.unserialized_value
+        end
+      end
+
       class Attribute < Struct.new(:coder, :value, :state)
         def unserialized_value
           state == :serialized ? unserialize : value
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 74403f9e35..28f52bd270 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -165,7 +165,7 @@ module ActiveRecord
     #   User.new({ :first_name => 'Jamie', :is_admin => true }, :without_protection => true)
     def initialize(attributes = nil, options = {})
       @attributes = self.class.initialize_attributes(self.class.column_defaults.dup)
-      @columns_hash = self.class.columns_hash.dup
+      @columns_hash = self.class.column_types.dup
 
       init_internals
 
@@ -191,7 +191,7 @@ module ActiveRecord
     #   post.title # => 'hello world'
     def init_with(coder)
       @attributes = self.class.initialize_attributes(coder['attributes'])
-      @columns_hash = self.class.columns_hash.merge(coder['column_types'] || {})
+      @columns_hash = self.class.column_types.merge(coder['column_types'] || {})
 
 
       init_internals
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 61f82af0c3..5486e192e4 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -206,6 +206,14 @@ module ActiveRecord
         @columns_hash ||= Hash[columns.map { |c| [c.name, c] }]
       end
 
+      def column_types
+        @column_types ||= columns_hash.dup.tap { |x|
+          serialized_attributes.keys.each do |key|
+            x[key] = AttributeMethods::Serialization::Type.new(x[key])
+          end
+        }
+      end
+
       # Returns a hash where the keys are column names and the values are
       # default values when instantiating the AR object for this table.
       def column_defaults
@@ -268,9 +276,16 @@ module ActiveRecord
         undefine_attribute_methods
         connection.schema_cache.clear_table_cache!(table_name) if table_exists?
 
-        @column_names = @content_columns = @column_defaults = @columns = @columns_hash = nil
-        @dynamic_methods_hash = @inheritance_column = nil
-        @arel_engine = @relation = nil
+        @arel_engine          = nil
+        @column_defaults      = nil
+        @column_names         = nil
+        @columns              = nil
+        @columns_hash         = nil
+        @column_types         = nil
+        @content_columns      = nil
+        @dynamic_methods_hash = nil
+        @inheritance_column   = nil
+        @relation             = nil
       end
 
       def clear_cache! # :nodoc: