Rails 4.0每3个div循环然后应用类

Question

我在下面循环

- @published_only.each do |p|
  .movie.effect
    = image_tag(p.poster_url(:thumb), class: "img")
    .mini-desc
      %h4= p.title

它会给

<div class="movie effect>...</div>
<div class="movie effect>...</div>
<div class="movie effect>...</div>
<div class="movie effect>...</div>
<div class="movie effect>...</div>
<div class="movie effect>...</div>

如何让它为每3个div应用'last'类.例如:

<div class="movie effect>...</div>
<div class="movie effect>...</div>
<div class="movie effect last>...</div>
<div class="movie effect>...</div>
<div class="movie effect>...</div>
<div class="movie effect last>...</div>

Answer 1

你可以使用cycle方法:

.movie.effect{class: cycle('', '', 'last')}