app/inputs/check_boxes_input.rb
class CheckBoxesInput < Formtastic::Inputs::CheckBoxesInput
def selected_values
if object.respond_to?(method)
selected_items = [object.send(method)].compact.flatten
# FIX for ids only
return selected_items.map(&:to_s).compact if selected_items.all?{ |i| i.is_a? Integer}
[*selected_items.map { |o| send_or_call_or_object(value_method, o) }].compact
else
[]
end
end
end