suppress_action_view_field_errors.rb

# config/initializers/suppress_action_view_field_errors.rb

# The default form builder appends <div class="field_with_errors"> (or something similar)
# to all fields and labels for model attributes that have validation errors. Doesn't work
# so well with Bootstrap.
ActionView::Base.field_error_proc = Proc.new do |html_tag, instance|
  "#{html_tag}".html_safe
end

twitter_bootstrap_form_builder.rb

# lib/twitter_bootstrap_form_builder.rb

class TwitterBootstrapFormBuilder < ActionView::Helpers::FormBuilder
  FIELD_TYPES = {
    :password   => :password_field,
    :email      => :email_field,
    :check_box  => :check_box,
    :text       => :text_field
  }

  def field(attribute_name, field_type = nil, html_options = {})
    css_class = nil 
    if not self.object.errors[attribute_name].empty?
      css_class = "error"
    end

    field_method = if not field_type
      field_method = FIELD_TYPES[attribute_name] || "text_field" 
    else
      field_method = FIELD_TYPES[field_type] || "text_field"
    end

    if html_options[:class] and css_class
      html_options[:class] = "#{html_options[:class]} #{css_class}"
    elsif css_class
      html_options[:class] = css_class
    end

    label = self.label(attribute_name)
    input = self.send(field_method, attribute_name, html_options)

    input_container = if self.object.errors[attribute_name].empty?
      @template.content_tag(:div, input, :class => "input")
    else
      inline_help = @template.content_tag(:span, self.object.errors[attribute_name].join(", "), :class => 'help-inline')
      @template.content_tag(:div, input + inline_help, :class => "input")
    end

    @template.content_tag(:div, label + input_container, :class => "clearfix #{css_class}")
  end
end