7 files changed, 52 insertions, 6 deletions
diff --git a/activerecord/lib/active_record/counter_cache.rb b/activerecord/lib/active_record/counter_cache.rb
index 999322129a..808e70d7de 100644
--- a/activerecord/lib/active_record/counter_cache.rb
+++ b/activerecord/lib/active_record/counter_cache.rb
@@ -17,8 +17,14 @@ module ActiveRecord
     def reset_counters(id, *counters)
       object = find(id)
       counters.each do |association|
-        child_class = reflect_on_association(association.to_sym).klass
-        belongs_name = self.name.demodulize.underscore.to_sym
+        has_many_association = reflect_on_association(association.to_sym)
+        polymorphic_class = has_many_association.options[:as]
+        child_class = has_many_association.klass
+        belongs_to = child_class.reflect_on_all_associations(:belongs_to)
+        belongs_to_association = belongs_to.detect do |e| 
+          polymorphic_class.nil? ?  (e.class_name == self.name) : (e.class_name.to_s.downcase == polymorphic_class.to_s.downcase)
+        end
+        belongs_name = belongs_to_association.name
         counter_name = child_class.reflect_on_association(belongs_name).counter_cache_column
 
         self.unscoped.where(arel_table[self.primary_key].eq(object.id)).arel.update({
@@ -103,4 +109,4 @@ module ActiveRecord
       update_counters(id, counter_name => -1)
     end
   end
-end
-\ No newline at end of file
+end
diff --git a/activerecord/test/cases/counter_cache_test.rb b/activerecord/test/cases/counter_cache_test.rb
index 377de168b9..137236255d 100644
--- a/activerecord/test/cases/counter_cache_test.rb
+++ b/activerecord/test/cases/counter_cache_test.rb
@@ -1,17 +1,20 @@
 require 'cases/helper'
 require 'models/topic'
+require 'models/car'
+require 'models/wheel'
+require 'models/engine'
 require 'models/reply'
 require 'models/category'
 require 'models/categorization'
 
 class CounterCacheTest < ActiveRecord::TestCase
-  fixtures :topics, :categories, :categorizations
+  fixtures :topics, :categories, :categorizations, :cars
 
-  class SpecialTopic < ::Topic
+  class ::SpecialTopic < ::Topic
     has_many :special_replies, :foreign_key => 'parent_id'
   end
 
-  class SpecialReply < ::Reply
+  class ::SpecialReply < ::Reply
     belongs_to :special_topic, :foreign_key => 'parent_id', :counter_cache => 'replies_count'
   end
 
@@ -58,6 +61,16 @@ class CounterCacheTest < ActiveRecord::TestCase
     end
   end
 
+  test "reset counter should with belongs_to which has class_name" do
+    car = cars(:honda)
+    assert_nothing_raised do
+      Car.reset_counters(car.id, :engines)
+    end
+    assert_nothing_raised do
+      Car.reset_counters(car.id, :wheels)
+    end
+  end
+
   test "update counter with initial null value" do
     category = categories(:general)
     assert_equal 2, category.categorizations.count
diff --git a/activerecord/test/fixtures/cars.yml b/activerecord/test/fixtures/cars.yml
new file mode 100644
index 0000000000..23c98e8144
--- /dev/null
+++ b/activerecord/test/fixtures/cars.yml
@@ -0,0 +1,4 @@
+honda:
+  id: 1
+  name: honda
+  engines_count: 0
diff --git a/activerecord/test/models/car.rb b/activerecord/test/models/car.rb
new file mode 100644
index 0000000000..1101180a67
--- /dev/null
+++ b/activerecord/test/models/car.rb
@@ -0,0 +1,4 @@
+class Car < ActiveRecord::Base
+  has_many :engines
+  has_many :wheels, :as => :wheelable
+end
diff --git a/activerecord/test/models/engine.rb b/activerecord/test/models/engine.rb
new file mode 100644
index 0000000000..751c3f02d1
--- /dev/null
+++ b/activerecord/test/models/engine.rb
@@ -0,0 +1,3 @@
+class Engine < ActiveRecord::Base
+  belongs_to :my_car, :class_name => 'Car', :foreign_key => 'car_id',  :counter_cache => :engines_count
+end
diff --git a/activerecord/test/models/wheel.rb b/activerecord/test/models/wheel.rb
new file mode 100644
index 0000000000..26868bce5e
--- /dev/null
+++ b/activerecord/test/models/wheel.rb
@@ -0,0 +1,3 @@
+class Wheel < ActiveRecord::Base
+  belongs_to :wheelable, :polymorphic => true, :counter_cache => true
+end
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index b212e7cff2..bea351b95a 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -82,6 +82,12 @@ ActiveRecord::Schema.define do
     t.string :name
   end
 
+  create_table :cars, :force => true do |t|
+    t.string  :name
+    t.integer :engines_count
+    t.integer :wheels_count
+  end
+
   create_table :categories, :force => true do |t|
     t.string :name, :null => false
     t.string :type
@@ -179,6 +185,9 @@ ActiveRecord::Schema.define do
   end
   add_index :edges, [:source_id, :sink_id], :unique => true, :name => 'unique_edge_index'
 
+  create_table :engines, :force => true do |t|
+    t.integer :car_id
+  end
 
   create_table :entrants, :force => true do |t|
     t.string  :name, :null => false
@@ -566,6 +575,10 @@ ActiveRecord::Schema.define do
     t.integer :zine_id
   end
 
+  create_table :wheels, :force => true do |t|
+    t.references :wheelable, :polymorphic => true
+  end
+
   create_table :zines, :force => true do |t|
     t.string :title
   end