检查Jinja2中的数组是否不为空 [英] Check if an array is not empty in Jinja2

问题描述

我需要检查在index.html中是否定义了变量texts.

I need to check if the variable texts is defined or not in index.html.

如果定义了变量并且不为空，那么我应该渲染循环.否则，我想显示错误消息{{error}}.

If the variable is defined and not empty then I should render the loop. Otherwise, I want to show the error message {{error}}.

基本上在PHP中

if (isset($texts) && !empty($texts)) {
    for () { ... }
}
else {
    print $error;
}

index.html

{% for text in texts %} 
    <div>{{error}}</div>
    <div class="post">
        <div class="post-title">{{text.subject}}</div>
        <pre class="post-content">{{text.content}}</pre>
    </div>
{% endfor %}

我在Jinja2中怎么说?

How do I say this in jinja2?

推荐答案

看看Jinja2 defined()的文档:

Take a look at the documentation of Jinja2 defined(): http://jinja.pocoo.org/docs/templates/#defined

{% if variable is defined %}
    value of variable: {{ variable }}
{% else %}
    variable is not defined
{% endif %}

是否足够清楚?在您的情况下，它可能看起来像这样:

Is it clear enough? In your case it could look like this:

{% if texts is defined %}
    {% for text in texts %} 
        <div>{{ error }}</div>
        <div class="post">
            <div class="post-title">{{ text.subject }}</div>
            <pre class="post-content">{{ text.content }}</pre>
        </div>
    {% endfor %}
{% else %}
    Error!
{% endif %}

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