如何在 Twig 中检查 null?
我应该使用什么构造来检查 Twig 模板中的值是否为 NULL?
What construct should I use to check whether a value is NULL in a Twig template?
推荐答案
取决于你到底需要什么:
Depending on what exactly you need:
is null
检查是否值为null
:
{% if var is null %}
{# do something #}
{% endif %}
is defined
检查是否变量已定义:
is defined
checks whether the variable is defined:
{% if var is not defined %}
{# do something #}
{% endif %}
另外,is sameas
测试,其中对两个值进行类型严格比较,可能对检查 null
以外的值(如 false
)感兴趣:
Additionally the is sameas
test, which does a type strict comparison of two values, might be of interest for checking values other than null
(like false
):
{% if var is sameas(false) %}
{# do something %}
{% endif %}
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