Bootstrap flash notice on Rails

In views/layouts/application.html.erb add following line after header:

<%= render 'layouts/messages' %>

views/layouts/_messages.html.erb must look like this:

<% flash.each do |type, message| %>
  <div class="alert <%= bootstrap_class_for(type) %> fade in">
    <button class="close" data-dismiss="alert">×</button>
    <%= message %>
  </div>
<% end %>

In messages.html.erb we used bootstrap_class_for helper which is declared in helpers/application_helper.rb:

module ApplicationHelper

  def bootstrap_class_for flash_type
    case flash_type
      when "success"
        "alert-success"
      when "error"
        "alert-danger"
      when "alert"
        "alert-warning"
      when "notice"
        "alert-info"
      else
        flash_type.to_s
    end
  end
end