ruby-on-rails - Ruby:如何迭代散列并根据项目数量做一些不同的事情？

Question

我正在使用看起来像这样的散列:

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}

但是，它可能只有一个项目:

h = { 
    "side2"=>["verde", "Verde"]
}

我想输出散列，使其看起来像这样:

User changed side1 from green to Green and side2 from verde to Verde

当有两个项目时，将用“和”分隔。否则它看起来像这样:

User changed side2 from verde to Verde

这一切都发生在我的 Rails View 脚本中。如何编写代码才能执行此操作？

Answer 1

你可以这样做:

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# "side1 from green to Green and side2 from verde to Verde"

h = { 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# side2 from verde to Verde"

因此，在 ERB View 中:

User changed <%= h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ') %>.

如果您经常做这类事情，那么您可能想为它构建一个帮助器。

你也可以使用 to_sentence因为你在 Rails 中:

User changed <%= h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.to_sentence %>.

to_sentence 方法也可以更好地扩展到两个以上的元素。所以，如果你还有 "side3"=>["pancakes", "Pancakes"]，那么你会得到:

User changed side1 from green to Green, side2 from verde to Verde, and side3 from pancakes  to Pancakes.