1 files changed, 9 insertions, 5 deletions
diff --git a/activerecord/lib/active_record/relation/where_clause.rb b/activerecord/lib/active_record/relation/where_clause.rb
index 47728aac30..b91b135867 100644
--- a/activerecord/lib/active_record/relation/where_clause.rb
+++ b/activerecord/lib/active_record/relation/where_clause.rb
@@ -70,7 +70,15 @@ module ActiveRecord
           predicates == other.predicates
       end
 
-      def invert
+      def invert(as = :nand)
+        if predicates.size == 1
+          inverted_predicates = [ invert_predicate(predicates.first) ]
+        elsif as == :nor
+          inverted_predicates = predicates.map { |node| invert_predicate(node) }
+        else
+          inverted_predicates = [ Arel::Nodes::Not.new(ast) ]
+        end
+
         WhereClause.new(inverted_predicates)
       end
 
@@ -115,10 +123,6 @@ module ActiveRecord
           node.respond_to?(:operator) && node.operator == :==
         end
 
-        def inverted_predicates
-          predicates.map { |node| invert_predicate(node) }
-        end
-
         def invert_predicate(node)
           case node
           when NilClass