customize error messages

application_helper.rb

def error_messages_for(objects, options = {})
	  objects = Array(objects)
		count = objects.inject(0) {|sum, object| sum + object.errors.count }

		unless count.zero?
			html = {}
			[:id, :class].each do |key|
				if options.include?(key)
					 value = options[key]
					 html[key] = value unless value.blank?
				else
					 html[key] = 'errorExplanation'
				 end
			end

			if count > 1 then
				header_message = _("%{ct_errores} errores han impedido procesar esta petición") % {:ct_errores => count}
			else
				header_message = _("Un error ha impedido procesar esta petición") % {:ct_errores => count}
			end

			error_messages = objects.map {|object| object.errors.full_messages.map { |msg|
				# si el mensaje empieza por ^ borramos el nombre del campo
				msg = msg.sub(/.*?\^/, "")
				content_tag(:li, _(msg)) }
			}
			content_tag(:div,
			  content_tag(options[:header_tag] || :h2, header_message) <<
				content_tag(:p, options[:subheader_message] || _('Hubo errores en los siguientes campos') + ':') <<
				content_tag(:ul, error_messages),
				html
			)
		else
			 ''
			end
		end