到目前为止我使用：

form_for @user do |f|
  f.collection_radio_buttons :rating,[[1,'Bad'],[2,'Ok'],[3,'Great']],:first,:last,{ item_wrapper_tag: false }
end

哪个产生：

<input id="review_rating_1" name="review[rating]" type="radio" value="1" />
<label class="collection_radio_buttons" for="review_rating_1">Bad</label>
<input id="review_rating_2" name="review[rating]" type="radio" value="2" />
<label class="collection_radio_buttons" for="review_rating_2">Ok</label>
<input id="review_rating_3" name="user[options]" type="radio" value="3" />
<label class="collection_radio_buttons" for="review_rating_3">Great</label>

但我希望标签有一个额外的类,如：

<input id="review_rating_3" name="user[options]" type="radio" value="3" />
<label class="collection_radio_buttons icon-star" for="review_rating_3">Great</label>

更新：此类在静态定义：https://github.com/plataformatec/simple_form/blob/master/lib/simple_form/tags.rb#L43