如果条件在Haml中为真，则追加类

Question

如果post.published?

.post
  / Post stuff

否则

.post.gray
  / Post stuff

我用rails helper实现了它，看起来很难看。

= content_tag :div, :class => "post" + (" gray" unless post.published?).to_s do
  / Post stuff

第二种变体：

= content_tag :div, :class => "post" + (post.published? ? "" : " gray") do
  / Post stuff

是否有更简单和特定于haml的方式？

UPD。 Haml特有的，但仍然不简单：

%div{:class => "post" + (" gray" unless post.published?).to_s}
  / Post stuff

Answer 1

.post{:class => ("gray" unless post.published?)}

Answer 2

- classes = ["post", ("gray" unless post.published?)]
= content_tag :div, class: classes do
  /Post stuff

---

def post_tag post, &block
  classes = ["post", ("gray" unless post.published?)]
  content_tag :div, class: classes, &block
end

= post_tag post
  /Post stuff

Answer 3

最好的办法就是把它变成帮手。

%div{ :class => published_class(post) }

#some_helper.rb

def published_class(post)
  "post #{post.published? ? '' : 'gray'}"
end

Answer 4

HAML有一个很好的内置方法来处理这个问题：

.post{class: [!post.published? && "gray"] }

这种方法的工作方式是条件得到评估，如果是，则字符串包含在类中，否则不会包括在内。

Answer 5

更新的Ruby语法：

.post{class: ("gray" unless post.published?)}