Fix Issue - reset a single column when orderable_scope changed instead of removing it from list

lib/mongoid/orderable/callbacks.rb

@@ -15,14 +15,18 @@ def add_to_list
 
         def remove_from_list
           self.orderable_keys.each do |column|
-            col, pos = orderable_column(column), orderable_position(column)
-            MongoidOrderable.inc orderable_scoped(column).where(col.gt => pos), col, -1
+            remove_position_from_list column
           end
         end
 
+        def remove_position_from_list(column)
+          col, pos = orderable_column(column), orderable_position(column)
+          MongoidOrderable.inc orderable_scoped(column).where(col.gt => pos), col, -1
+        end
+
         def apply_position column, target_position
           if persisted? && !embedded? && orderable_scope_changed?(column)
-            self.class.unscoped.find(_id).remove_from_list
+            self.class.unscoped.find(_id).remove_position_from_list(column)
             self.send("orderable_#{column}_position=", nil)
           end
 

spec/mongoid/orderable_spec.rb

@@ -107,6 +107,17 @@ class MultipleColumnsOrderable
     orderable :column => :groups, :scope => :group
   end
 
+  class MultipleScopedOrderable
+    include Mongoid::Document
+    include Mongoid::Orderable
+
+    belongs_to :apple
+    belongs_to :orange
+
+    orderable :column => :posa, :scope => :apple_id
+    orderable :column => :poso, :scope => :orange_id
+  end
+
   describe SimpleOrderable do
 
     before :each do
@@ -1322,4 +1333,53 @@ class Apple
     end
   end
 
+  describe MultipleScopedOrderable do
+    before :each do
+      Apple.delete_all; Orange.delete_all;
+      MultipleScopedOrderable.delete_all
+
+      3.times do
+        Apple.create; Orange.create
+      end
+
+      MultipleScopedOrderable.create! :apple_id => 1, :orange_id => 1
+      MultipleScopedOrderable.create! :apple_id => 2, :orange_id => 1
+      MultipleScopedOrderable.create! :apple_id => 2, :orange_id => 2
+      MultipleScopedOrderable.create! :apple_id => 1, :orange_id => 3
+      MultipleScopedOrderable.create! :apple_id => 1, :orange_id => 1
+      MultipleScopedOrderable.create! :apple_id => 3, :orange_id => 3
+      MultipleScopedOrderable.create! :apple_id => 2, :orange_id => 3
+      MultipleScopedOrderable.create! :apple_id => 3, :orange_id => 2
+      MultipleScopedOrderable.create! :apple_id => 1, :orange_id => 3
+    end
+
+    def apple_positions
+      MultipleScopedOrderable.order_by([:apple_id, :asc], [:posa, :asc]).map(&:posa)
+    end
+
+    def orange_positions
+      MultipleScopedOrderable.order_by([:orange_id, :asc], [:poso, :asc]).map(&:poso)
+    end
+
+    describe 'default positions' do
+      it { apple_positions.should == [1, 2, 3, 4, 1, 2, 3, 1, 2] }
+      it { orange_positions.should == [1, 2, 3, 1, 2, 1, 2, 3, 4] }
+    end
+
+    describe 'change the scope of the apple' do
+      let(:record) { MultipleScopedOrderable.first }
+      before do
+        record.update_attribute(:apple_id, 2)
+      end
+
+      it 'should properly set the apple positions' do
+        apple_positions.should == [1, 2, 3, 1, 2, 3, 4, 1, 2]
+      end
+
+      it 'should not affect the orange positions' do
+        orange_positions.should == [1, 2, 3, 1, 2, 1, 2, 3, 4]
+      end
+    end
+  end
+
 end