php 如何访问 Twig 中的类常量？
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How to access class constants in Twig?
提问by canni
I have a few class constants in my entity class, e.g.:
我的实体类中有一些类常量，例如：
class Entity {
const TYPE_PERSON = 0;
const TYPE_COMPANY = 1;
}
In normal PHP I often do if($var == Entity::TYPE_PERSON)and I would like to do this kind of stuff in Twig. Is it possible?
在普通的 PHP 中，我经常这样做if($var == Entity::TYPE_PERSON)，我想在 Twig 中做这种事情。是否可以？
回答by message
Just to save your time. If you need to access class constants under namespace, use
只是为了节省您的时间。如果需要访问命名空间下的类常量，请使用
{{ constant('Acme\DemoBundle\Entity\Demo::MY_CONSTANT') }}
回答by NikiC
{% if var == constant('Namespace\Entity::TYPE_PERSON') %}
{# or #}
{% if var is constant('Namespace\Entity::TYPE_PERSON') %}
See documentation for the constantfunctionand the constanttest.
请参阅constant函数和constant测试的文档。
回答by Alexander Fedorov
As of 1.12.1 you can read constants from object instances as well:
从 1.12.1 开始，您也可以从对象实例中读取常量：
{% if var == constant('TYPE_PERSON', entity)
回答by Dmitriy Apollonin
If you are using namespaces
如果您使用命名空间
{{ constant('Namespace\Entity::TYPE_COMPANY') }}
Important! Use double slashes, instead of single
重要的！使用双斜线，而不是单斜线
回答by Damian Polac
Edit: I've found better solution, read about it here.
编辑：我找到了更好的解决方案，请在此处阅读。
- Read more about how to create and register extension in Twig documentation.
- Read about Twig extensions in Symfony2 documentation.
Let's say you have class:
假设你有课：
namespace MyNamespace;
class MyClass
{
const MY_CONSTANT = 'my_constant';
const MY_CONSTANT2 = 'const2';
}
Create and register Twig extension:
创建并注册 Twig 扩展：
class MyClassExtension extends \Twig_Extension
{
public function getName()
{
return 'my_class_extension';
}
public function getGlobals()
{
$class = new \ReflectionClass('MyNamespace\MyClass');
$constants = $class->getConstants();
return array(
'MyClass' => $constants
);
}
}
Now you can use constants in Twig like:
现在您可以在 Twig 中使用常量，例如：
{{ MyClass.MY_CONSTANT }}
回答by Chrysweel
In book best practices of Symfony there is a section with this issue:
在 Symfony 的最佳实践一书中，有一个部分涉及这个问题：
Constants can be used for example in your Twig templates thanks to the constant() function:
例如，由于 constant() 函数，可以在您的 Twig 模板中使用常量：
// src/AppBundle/Entity/Post.php
namespace AppBundle\Entity;
class Post
{
const NUM_ITEMS = 10;
// ...
}
And use this constant in template twig:
并在模板树枝中使用此常量：
<p>
Displaying the {{ constant('NUM_ITEMS', post) }} most recent results.
</p>
Here the link: http://symfony.com/doc/current/best_practices/configuration.html#constants-vs-configuration-options
这里的链接：http: //symfony.com/doc/current/best_practices/configuration.html#constants-vs-configuration-options
回答by Damian Polac
After some years I realized that my previous answer is not really so good. I have created extension that solves problem better. It's published as open source.
几年后，我意识到我之前的答案并不是那么好。我创建了更好地解决问题的扩展。它作为开源发布。
https://github.com/dpolac/twig-const
https://github.com/dpolac/twig-const
It defines new Twig operator #which let you access the class constant through any object of that class.
它定义了新的 Twig 运算符#，让您可以通过该类的任何对象访问该类常量。
Use it like that:
像这样使用它：
{% if entity.type == entity#TYPE_PERSON %}
{% if entity.type == entity#TYPE_PERSON %}
