CollectionAssociation#merge_target_lists should write to the underlying attributes when copying, rather than using the assignment method

4 files changed, 17 insertions, 5 deletions

diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
index d551cb01f0..50825a50f0 100644
--- a/activerecord/lib/active_record/associations/collection_association.rb
+++ b/activerecord/lib/active_record/associations/collection_association.rb
@@ -405,17 +405,14 @@ module ActiveRecord
             mem_record = memory.delete(record)
 
             if mem_record
-              # FIXME: this call to record.attributes causes many NoMethodErrors
-              attributes = record.attributes
-
               # Only try to assign attributes which exist on mem_record
-              shared = mem_record.attribute_names & attributes.keys
+              shared = mem_record.attribute_names & record.attribute_names
 
               # Don't try to assign the primary key, or attributes which have changed on mem_record
               excluded = ["id"] + mem_record.changes.keys
 
               (shared - excluded).each do |key|
-                mem_record.send("#{key}=", attributes[key])
+                mem_record[key] = record[key]
               end
 
               mem_record
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index b149f5912f..0e33fa9c8e 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -1445,4 +1445,14 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
 
     assert_not_equal target.object_id, ary.object_id
   end
+
+  def test_merging_with_custom_attribute_writer
+    bulb = Bulb.new(:color => "red")
+    assert_equal "RED!", bulb.color
+
+    car = Car.create!
+    car.bulbs << bulb
+
+    assert_equal "RED!", car.bulbs.to_a.first.color
+  end
 end
diff --git a/activerecord/test/models/bulb.rb b/activerecord/test/models/bulb.rb
index 643dcefed3..7d90963720 100644
--- a/activerecord/test/models/bulb.rb
+++ b/activerecord/test/models/bulb.rb
@@ -11,4 +11,8 @@ class Bulb < ActiveRecord::Base
     @scope_after_initialize = self.class.scoped
   end
 
+  def color=(color)
+    self[:color] = color.upcase + "!"
+  end
+
 end
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index c8a98f121d..d56cdd57b2 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -90,6 +90,7 @@ ActiveRecord::Schema.define do
     t.integer :car_id
     t.string  :name
     t.boolean :frickinawesome
+    t.string :color
   end
 
   create_table "CamelCase", :force => true do |t|