Ruby on Rails 中遍历循环添加 active 类

<% is_first = true %\n<% @product.product_skus.each do |product_sku| %\n <label class="btn btn-default sku-btn <%="active" if is_first%>" title="<% product_sku.description %>" data-stock="<% product_sku.stock %>" data-price="<% product_sku.price %>" data-id="<% product_sku.id %>">\n <% is_first = false %>\n <% product_sku.title %>\n \n<% end %>