Fix observer callbacks firing multiple times on descendant instances

1 files changed, 8 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/observer.rb b/activerecord/lib/active_record/observer.rb
index 8b011ad9af..0893d7e337 100644
--- a/activerecord/lib/active_record/observer.rb
+++ b/activerecord/lib/active_record/observer.rb
@@ -104,10 +104,17 @@ module ActiveRecord
 
       def define_callbacks(klass)
         observer = self
+        observer_name = observer.class.name.underscore.gsub('/', '__')
 
         ActiveRecord::Callbacks::CALLBACKS.each do |callback|
           next unless respond_to?(callback)
-          klass.send(callback){|record| observer.send(callback, record)}
+          callback_meth = :"_notify_#{observer_name}_for_#{callback}"
+          unless klass.respond_to?(callback_meth)
+            klass.send(:define_method, callback_meth) do
+              observer.send(callback, self)
+            end
+            klass.send(callback, callback_meth)
+          end
         end
       end
   end