ask/app/views/admin/asks/setting.html.erb

<%
  set_input_name('ask_setting[custom_fields]')
%>
<script>
  function add_new_field(){
    $.ajax({
      url : "<%= get_new_setting_index_admin_asks_path %>",
      dataType : "json",
      type : "post",
      error: function(){
        alert('init process failed, please try again later.')
      },
      success: function(data){
        var add_field_html = "<%= custom_field_block(-1).inspect %>"
        add_field_html = add_field_html.replace(/-1/g,data['key'])
        $('.add_field').before($('<div/>').html(add_field_html).text().slice(1,-2))
        $('.add_new_options').sortable({'handle':'.icons-list-2'})
      }
    })
  }
</script>
<script type="text/javascript">
  $(document).ready(function(){
    $('.add_new_options').sortable({'handle':'.icons-list-2'})
  })
</script>
<%= form_for @ask_setting,method: 'post',url:  @url,html: { class: 'form-horizontal main-forms previewable' } do |f| %>
  <%= render partial: 'ask_setting',locals:{ask_setting: @ask_setting,f: f,submit_text: t('submit')} %>
<% end %>