php Twig，添加第一个和最后一个类
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Twig, add first and last class
提问by FMaz008
Let's say I have a for loop like this:
假设我有一个这样的 for 循环：
{% for elem in arrMenu %}
<div class="topmenu-button">
<a href="{{ elem.url }}">{{ elem.name }}</a>
</div>
{% endfor %}
In that form, it would render something like:
以这种形式，它会呈现如下内容：
<div class="topmenu-button"><a href="url">name</a></div>
<div class="topmenu-button"><a href="url">name</a></div>
<div class="topmenu-button"><a href="url">name</a></div>
<div class="topmenu-button"><a href="url">name</a></div>
How can twig help me to add first and last classes the the div, so that I would have a result like:
twig 如何帮助我在 div 中添加第一个和最后一个类，以便我得到如下结果：
<div class="topmenu-button first"><a href="url">name</a></div>
<div class="topmenu-button"><a href="url">name</a></div>
<div class="topmenu-button"><a href="url">name</a></div>
<div class="topmenu-button last"><a href="url">name</a></div>
回答by Kendall Hopkins
You can use the "special variables" loop.firstand loop.lastfor what you want.
您可以使用“特殊变量”loop.first和loop.last您想要的。
{% for elem in arrMenu %}
{% if loop.first %}
<div class="topmenu-button first">
{% elseif loop.last %}
<div class="topmenu-button last">
{% else %}
<div class="topmenu-button">
{% endif %}
<a href="{{ elem.url }}">{{ elem.name }}</a>
</div>
{% endfor %}
EDIT: depending how much you care about the "one case", you might need a solution like this.
编辑：取决于您对“一个案例”的关心程度，您可能需要这样的解决方案。
{% for elem in arrMenu %}
{% set classes = ["topmenu-button"] %}
{% if loop.first %}{% set classes = classes|merge(["first"]) %}{% endif %}
{% if loop.last %}{% set classes = classes|merge(["last"]) %}{% endif %}
<div class="{{ classes|join(" ") }}">
<a href="{{ elem.url }}">{{ elem.name }}</a>
</div>
{% endfor %}
回答by gremo
Since a loop can't be firstand lastat the same time, i would prefer not to use elseifand write (DRY - what if you have to change topmenu-buttonin future?):
由于循环不能first与last在同一时间，我宁愿不使用elseif和写（DRY -如果你要改变topmenu-button未来？）：
{% for elem in arrMenu %}
{% set append %}
{% if loop.first %}first{% endif %}
{% if loop.last %}last{% endif %}
{% endset %}
<div class="topmenu-button {{ append }}">
<a href="{{ elem.url }}">{{ elem.name }}</a>
</div>
{% endfor %}
or more concise:
或更简洁：
{% for elem in arrMenu %}
<div class="topmenu-button {% if loop.first %}first{% endif %} {% if loop.last %}last{% endif %}">
<a href="{{ elem.url }}">{{ elem.name }}</a>
</div>
{% endfor %}
Edit: this way you'll get some extra spaces in classattribute (it's perfectly fine btw).
Edit2: this will not handle 1-element array (first = last)
编辑：这样你会在class属性中得到一些额外的空格（顺便说一句，它非常好）。
Edit2：这不会处理 1 元素数组（第一个 = 最后一个）
回答by Paul Leclerc
If it's to manage class attribut of a tag, a ternary condition would be better.
如果是管理标签的类属性，三元条件会更好。
<span class="topmenu-button {{ (loop.first) ? 'first' : '' }}">{{ item.text }}</span>
回答by Gódi Péter
I use this in Drupal 8 views template. Thanks for 'elseif', if you have only 1 item, then the first item never get the 'last' class:
我在 Drupal 8 视图模板中使用它。感谢“elseif”，如果您只有一项，那么第一项永远不会获得“最后”类：
{% for row in rows %}
{% set parity = cycle(['odd', 'even'], loop.index0) %}
{% set row_classes = [ default_row_class ? 'views-row', ] %}
<div class="views-prerow {{parity}}{% if loop.first %} first{% elseif loop.last %} last{% endif %}">
<div{{ row.attributes.addClass(row_classes) }}>
{{ row.content }}
</div>
</div>
{% endfor %}
