1 files changed, 12 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index db5d2b25ed..72f7df32c7 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -214,8 +214,10 @@ module ActiveRecord
       end
 
       def check_validity_of_inverse!
-        if has_inverse? && inverse_of.nil?
-          raise InverseOfAssociationNotFoundError.new(self)
+        unless options[:polymorphic]
+          if has_inverse? && inverse_of.nil?
+            raise InverseOfAssociationNotFoundError.new(self)
+          end
         end
       end
 
@@ -242,6 +244,14 @@ module ActiveRecord
         end
       end
 
+      def polymorphic_inverse_of(associated_class)
+        if has_inverse?
+          associated_class.reflect_on_association(options[:inverse_of])
+        else
+          nil
+        end
+      end
+
       private
         def derive_class_name
           class_name = name.to_s.camelize