Merge pull request formtastic#723 from ContinuityControl/speedup-larg…

…e-checkbox-set

memoize the selected values array

lib/formtastic/inputs/check_boxes_input.rb

@@ -152,13 +152,7 @@ def disabled?(value)
       end
 
       def selected_values
-        if object.respond_to?(method)
-          selected_items = [object.send(method)].compact.flatten
-
-          [*selected_items.map { |o| send_or_call_or_object(value_method, o) }].compact
-        else
-          []
-        end
+        @selected_values ||= make_selected_values
       end
 
       def disabled_values
@@ -175,6 +169,17 @@ def input_name
         "#{object_name}[#{association_primary_key || method}][]"
       end
 
+      protected
+
+      def make_selected_values
+        if object.respond_to?(method)
+          selected_items = [object.send(method)].compact.flatten
+
+          [*selected_items.map { |o| send_or_call_or_object(value_method, o) }].compact
+        else
+          []
+        end
+      end
     end
   end
 end

spec/inputs/check_boxes_input_spec.rb

@@ -348,7 +348,7 @@
         item.should_not_receive(:id)
         item.stub!(:custom_value).and_return('custom_value')
         item.should_receive(:custom_value).exactly(3).times
-        @new_post.author.should_receive(:custom_value).exactly(3).times
+        @new_post.author.should_receive(:custom_value).exactly(1).times
         concat(semantic_form_for(@new_post) do |builder|
           concat(builder.input(:author, :as => :check_boxes, :member_value => :custom_value, :collection => [item, item, item]))
         end)