1 files changed, 8 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index cf85a87fa7..e224d3456a 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -130,6 +130,14 @@ module ActiveRecord
           end
           saved_successfully
         end
+
+        def difference(a, b)
+          a - b
+        end
+
+        def intersection(a, b)
+          a & b
+        end
     end
   end
 end