f.error_messages in Rails 3.0

Question

Rails 3.0 deprecated f.error_messages and now requires a plugin to work correctly - I however want to learn how to display error messages the (new) native way.

Answer 1

The best and clean way to implement error_messages in your form is by implementing error_messages in a FormBuilder.

For example, here is the error_messages method I've implemented for my last project. By implemeting your own FormBuilder you can follow the rules and styles of your webdesigner... Here is an example that will output the errors list in ul/li's with some custom styles :

class StandardBuilder < ActionView::Helpers::FormBuilder
  def error_messages
    return unless object.respond_to?(:errors) && object.errors.any?

    errors_list = ""
    errors_list << @template.content_tag(:span, "There are errors!", :class => "title-error")
    errors_list << object.errors.full_messages.map { |message| @template.content_tag(:li, message) }.join("\n")

    @template.content_tag(:ul, errors_list.html_safe, :class => "error-recap round-border")
  end
end

Then in my forms :

= f.error_messages

And that's all.