有条件地向视图中的 HTML 元素添加类的优雅方式是什么? [英] What's an elegant way to conditionally add a class to an HTML element in a view?

问题描述

我有时必须根据条件向 html 元素添加一个类.问题是我想不出一个干净的方法来做到这一点.这是我尝试过的东西的一个例子:

或

<% if @status == 'success' %>
<%其他%><div><%结束%>这里有一些消息

我不喜欢第一种方法，因为它看起来很拥挤且难以阅读.我不喜欢第二种方法，因为嵌套被搞砸了.将它放在模型中会很好(类似于 @status.css_class)，但它不属于那里.大多数人做什么?

解决方案

我使用第一种方式，但语法稍微简洁一些:

<div class="<%= 'ok' if @status == 'success' %>">

虽然通常你应该用布尔值 true 或数字记录 ID 表示成功，用布尔值 false 或 nil 表示失败.这样你就可以测试你的变量:

如果您想在两个类之间进行选择，则使用三元 ?: 运算符的第二种形式很有用:

<div class="<%= @success ? 'good' : 'bad' %>">

最后，您可以使用 Rail 的 记录标签助手，例如 div_for，它将根据您提供的记录自动设置您的 ID 和类.给定一个 id 为 47 的 Person:

# 
<% div_for @person, class: (@success ? 'good' : 'bad') do %><%结束%>

I occasionally have to add a class to an html element based on a condition. The problem is I can't figure out a clean way of doing it. Here's an example of the stuff I've tried:

<div <%= if @status = 'success'; "class='ok'"; end %>>
   some message here
</div>

OR

<% if @status == 'success' %>
   <div class='success'>
<% else %>
   <div>
<% end %>
   some message here
</div>

I don't like the first approach because it's crowded looking and hard to read. I don't like the second approach because the nesting is screwed up. It'd be nice to put it in the model, (something like @status.css_class), but that doesn't belong there. What do most people do?

解决方案

I use the first way, but with a slightly more succinct syntax:

<div class="<%= 'ok' if @status == 'success' %>">

Though usually you should represent success with boolean true or a numeric record ID, and failure with boolean false or nil. This way you can just test your variable:

<div class="<%= 'ok' if @success %>">

A second form using the ternary ?: operator is useful if you want to choose between two classes:

<div class="<%= @success ? 'good' : 'bad' %>">

Finally, you can use Rail's record tag helpers such as div_for, which will automagically set your ID and class based on the record you give it. Given a Person with id 47:

# <div id="person_47" class="person good">
<% div_for @person, class: (@success ? 'good' : 'bad') do %>
<% end %>

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