如何在Jinja2中中断for循环? [英] How can I break a for loop in jinja2?

问题描述

如何在jinja2中打破for循环?

How can I break out of a for loop in jinja2?

我的代码是这样的:

<a href="#">
{% for page in pages if page.tags['foo'] == bar %}
{{page.title}}
{% break %}
{% endfor %}
</a>

我有多个具有此条件的页面，一旦满足条件，我想结束循环.

I have more than one page that has this condition and I want to end the loop, once the condition has been met.

推荐答案

您不能使用break，而是使用过滤器.从Jinja2 关于{% for %} 的文档:

You can't use break, you'd filter instead. From the Jinja2 documentation on {% for %}:

与Python不同，它不可能在循环中中断或继续.但是，您可以在迭代过程中过滤序列，从而可以跳过项目.下面的示例跳过所有隐藏的用户:

Unlike in Python it’s not possible to break or continue in a loop. You can however filter the sequence during iteration which allows you to skip items. The following example skips all the users which are hidden:

{% for user in users if not user.hidden %}
    <li>{{ user.username|e }}</li>
{% endfor %}

但是，对于您来说，您似乎只需要 first 元素；只需过滤并选择第一个:

In your case, however, you appear to only need the first element; just filter and pick the first:

{{ (pages|selectattr('tags.foo', 'eq', bar)|first).title }}

这使用 selectattr()过滤器过滤列表，结果传递给 first过滤器.

This filters the list using the selectattr() filter, the result of which is passed to the first filter.

selectattr()过滤器会生成一个迭代器，因此在此处使用first只会对输入进行迭代，直到第一个匹配元素为止，而不会进行进一步的迭代.

The selectattr() filter produces an iterator, so using first here will only iterate over the input up to the first matching element, and no further.

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