Rails example of an ajax form with a select_tag of grouped options

grouped_options.rb

<%= form_tag(submit_path, remote: true, method: :get, id: 'add_line_item') do %>
  <div class="col">
    <div class="form-row">
      <div class="col-md-10">
        <%= grouped_collection_select(:line_item, :product_id, current_user.categories, :products, :name, :id, :name, { prompt: '--Select Product--' }, { class: 'form-control form-control-sm' }) %>
      </div>

      <div class="col text-center">
        <%= submit_tag 'Add', class: 'btn btn-outline-secondary btn-sm'%>
      </div>
    </div>
  </div>
<% end %>