带有“默认"的错误Twig/Symfony 2 中的过滤器和布尔宏参数? [英] Bug with "default" filter and boolean macro arguments in Twig / Symfony 2?

问题描述

我正在使用 default Twig 过滤器在我的 macro 中指定参数默认值:

I'm using default Twig filter to specify arguments defaults in my macro:

{% macro base(type, title, content, separator, dismissable) %}
{% spaceless %}

    {% debug dismissable %}

    {% set separator   = separator|default('!') %}
    {% set dismissable = dismissable|default(true) %}

    {% debug dismissable %}

    {# Beginning outputting... #}
{% endspaceless %}
{% endmacro %}

问题是dismissable参数类型应该是boolean.但是，当传递 false 时，过滤器会对其进行评估并分配一个 true 默认值.示例输出:

The problem is that dismissable argument type should be boolean. However when passing falsethe filter evaluates it and assign a true default value. An example output:

{{ base('success', 'Title', 'Hello', '!', false) }}

boolean false
boolean true

这是一个错误吗?这是(部分)过滤器说明:

Is this a bug? Here is (part of) filter description:

默认过滤器返回传递的默认值，如果值为未定义或为空，否则为变量值.

The default filter returns the passed default value if the value is undefined or empty, otherwise the value of the variable.

布尔值 false 的评估甚至没有被提及.我的临时解决方法是:

Evaluation of boolean false is not even mentioned. My temporary workaround is:

{% set dismissable = dismissable is not defined or dismissable is null ?
    true : dismissable %}

推荐答案

这不是错误.您引用的文档提到了它，尽管它远非显而易见:

It is not a bug. The docs you quoted mentions it, though it's far from being obvious:

如果值未定义或空

我的重点.False 是一个空值.

Emphasis by me. False is an empty value.

Twig_Node_Expression_Default 创建代码中的 Twig_Node_Expression_Conditional.最后，默认过滤器归结为以下 php 代码:

Twig_Node_Expression_Default creates a Twig_Node_Expression_Conditional in the code. In the end the default filter boiles down to the following php code:

$passed_value ? $passed_value : $default_value

在您的情况下，传递的值为 false，因此表达式返回默认值.

In your case the passed value is false, so the expression returns the default value.

您应该继续使用您的解决方法.

You should keep using your workaround.

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