Serialized attribute can be serialized in an integer column

Fix #8575

activerecord/CHANGELOG.md

@@ -1,12 +1,17 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Serialized attributes can be serialized in integer columns.
+    Fix #8575.
+
+    *Rafael Mendonça França*
+
 *   Keep index names when using `alter_table` with sqlite3.
-    Fix #3489
+    Fix #3489.
 
     *Yves Senn*
 
 *   Add ability for postgresql adapter to disable user triggers in `disable_referential_integrity`.
-    Fix #5523
+    Fix #5523.
 
     *Gary S. Weaver*
 

activerecord/lib/active_record/attribute_methods/serialization.rb

@@ -112,6 +112,14 @@ module ActiveRecord
           end
         end
 
+        def _field_changed?(attr, old, value)
+          if self.class.serialized_attributes.include?(attr)
+            old != value
+          else
+            super
+          end
+        end
+
         def read_attribute_before_type_cast(attr_name)
           if self.class.serialized_attributes.include?(attr_name)
             super.unserialized_value

activerecord/test/cases/serialized_attribute_test.rb

@@ -1,5 +1,6 @@
-require "cases/helper"
+require 'cases/helper'
 require 'models/topic'
+require 'models/person'
 require 'bcrypt'
 
 class SerializedAttributeTest < ActiveRecord::TestCase
@@ -225,4 +226,12 @@ class SerializedAttributeTest < ActiveRecord::TestCase
   ensure
     ActiveRecord::Base.time_zone_aware_attributes = false
   end
+
+  def test_serialize_attribute_can_be_serialized_in_an_integer_column
+    insures = ['life']
+    person = SerializedPerson.new(first_name: 'David', insures: insures)
+    assert person.save
+    person = person.reload
+    assert_equal(insures, person.insures)
+  end
 end

activerecord/test/models/person.rb

@@ -100,3 +100,24 @@ class NestedPerson < ActiveRecord::Base
     assign_attributes({ :best_friend_attributes => { :first_name => new_name } })
   end
 end
+
+class Insure
+  INSURES = %W{life annuality}
+
+  def self.load mask
+    INSURES.select do |insure|
+      (1 << INSURES.index(insure)) & mask > 0
+    end
+  end
+
+  def self.dump insures
+    numbers = insures.map { |insure| INSURES.index(insure) }
+    numbers.inject(0) { |sum, n| sum + (1 << n) }
+  end
+end
+
+class SerializedPerson < ActiveRecord::Base
+  self.table_name = 'people'
+
+  serialize :insures, Insure
+end

activerecord/test/schema/schema.rb

@@ -494,6 +494,7 @@ ActiveRecord::Schema.define do
     t.integer    :followers_count, :default => 0
     t.references :best_friend
     t.references :best_friend_of
+    t.integer    :insures, null: false, default: 0
     t.timestamps
   end