Another approach to FormBuilder

main_form.rb

# app/helpers/main_form.rb 
class MainForm < ActionView::Helpers::FormBuilder # NestedForm::Builder
  CSS = {
    :label => 'label-control',
    :hint => 'hint',
    :hint_ptr => 'hint-pointer',
    :error => 'help-inline',
    :field_error => 'error',
    :main_class => 'clearfix'
  }

  FIELDS = %w(radio_button check_box text_field text_area password_field select file_field collection_select email_field date_select)
  
  def main_class(error=nil)
    return CSS[:main_class] unless error
    [CSS[:main_class], CSS[:field_error]].join(' ')
  end

  def required(name)
    object.class.validators_on(name).map(&:class).include?(ActiveModel::Validations::PresenceValidator) rescue nil
  end

  def cancel(options={})
    link = options.fetch(:return, "/")
    @template.content_tag(:a, "Cancel", :href => link, :class => "btn_form button np_cancel_btn #{options[:class]}")
  end

  def submit(value="Save", options={})
    options[:class] = "send_form_btn #{options[:class]}"
    super
  end

  def label_class
    {:class => CSS[:label]}
  end

  def label_tag(attribute, arg)
    # Incase its a mandatory field, the '*' is added to the field.
    txt = arg[:label] && arg[:label].to_s || attribute.to_s.titleize
    txt<< '*' if(arg[:required] || required(attribute)) && arg[:required] != false
    label(attribute, txt, label_class)
  end

  def error_tag(method_name, attribute)
    errs = field_error(method_name, attribute)
    @template.content_tag(:span, errs.first, :class => CSS[:error]) if errs.present?
  end

  def field_error(method_name, attribute)
    return if @object && @object.errors.blank?
    return @object.errors[attribute] if method_name != 'file_field'
    @object.errors["#{attribute.to_s}_file_name"] | @object.errors["#{attribute.to_s}_file_size"] | @object.errors["#{attribute.to_s}_content_type"]
  end

  def hint_tag(txt)
    hintPtr = @template.content_tag(:span, '', :class => CSS[:hint_ptr])
    hintT = @template.content_tag(:span, txt + hintPtr, {:class => CSS[:hint]}, false) 
  end
 
  def spinner_tag
    @template.image_tag('spinner.gif', :class => :spinner,:id => :spinner) 
  end
end  

zero_form.rb

cat app/helpers/zero_form.rb 
class ZeroForm < MainForm
  # Overridden label_class here as we dont need class to be applied
  def label_class
    {}
  end

  def self.create_tagged_field(method_name)
    define_method(method_name) do |attribute, *args|
      arg = args.last && args.last.is_a?(Hash) && args.last || {}

      # Bypass form-builder and do your own custom stuff!
      return super(attribute, *args) if arg[:skip] && args.last.delete(:skip)

      errT = error_tag(method_name, attribute)
      labelT = label_tag(attribute, arg)

      mainT = super(attribute, *args)
      baseT = @template.content_tag(:div, mainT + errT)

      hintT = hint_tag(arg[:hint]) if arg[:hint]
      spinnerT = spinner_tag if arg[:spinner]

      allT = labelT + baseT + spinnerT + hintT
      @template.content_tag(:div, allT, :class => main_class(errT))
    end
  end

  FIELDS.each do |name|
    create_tagged_field(name)
  end
end