lib/graphql/language/nodes.rb in graphql-1.9.8 vs lib/graphql/language/nodes.rb in graphql-1.9.9

@@ -71,19 +71,26 @@
         def position
           [line, col]
         end
 
         def to_query_string(printer: GraphQL::Language::Printer.new)
-          printer.print(self)
+          if printer.is_a?(GraphQL::Language::Printer)
+            @query_string ||= printer.print(self)
+          else
+            printer.print(self)
+          end
         end
 
         # This creates a copy of `self`, with `new_options` applied.
         # @param new_options [Hash]
         # @return [AbstractNode] a shallow copy of `self`
         def merge(new_options)
           copied_self = dup
           new_options.each do |key, value|
             copied_self.instance_variable_set(:"@#{key}", value)
+            if copied_self.instance_variable_defined?(:@query_string)
+              copied_self.instance_variable_set(:@query_string, nil)
+            end
           end
           copied_self
         end
 
         # Copy `self`, but modify the copy so that `previous_child` is replaced by `new_child`