在依赖注入类内部使用参数
你已经看到了如何在Symfony服务容器内部使用配置参数。比如你可能想在这里出现一个特殊的情况，在你Bundle的服务中使用%kernel.debug%参数来进入debug模式。对于这种情况，有很多的工作要做，以便使系统了解参数值。默认情况下，你的参数%kernel.debug%将被视为是一个简单的字符串。看看下面这个例子：
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// inside Configuration class
// 在Configuration类内部
$rootNode
->children()
->booleanNode('logging')->defaultValue('%kernel.debug%')->end()
// ...
->end()
;
// inside the Extension class
// 在Extension类内部
$config = $this->processConfiguration($configuration, $configs);
var_dump($config['logging']); |
现在，进一步看看来检查这个结果：
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my_bundle:
logging: true
# true, as expected
# ture，正如预期
my_bundle:
logging: '%kernel.debug%'
# true/false (depends on 2nd parameter of AppKernel),
# true/false （取决于AppKerenl的第二个参数），
# as expected, because %kernel.debug% inside configuration
# gets evaLuated before being passed to the extension
# 正如预期，因为在被传入到扩展之前，%kernel.debug%在configuration内部已经被评估
my_bundle: ~
# passes the string "%kernel.debug%".
# 传入这个字符串%kernel.debug%。
# Which is always considered as true.
# 总是被看作是true。
# The Configurator does not know anything about
# "%kernel.debug%" being a parameter.
# 这个配置器要做的就是不知道关于"%kernel.debug%"参数的任何事。 |
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<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="Http://symfony.com/schema/dic/services"
xmlns:my-bundle="http://example.org/schema/dic/my_bundle">
<my-bundle:config logging="true" />
<!-- true, as expected -->
<my-bundle:config logging="%kernel.debug%" />
<!-- true/false (depends on 2nd parameter of AppKernel),
as expected, because %kernel.debug% inside configuration
gets evaluated before being passed to the extension -->
<my-bundle:config />
<!-- passes the string "%kernel.debug%".
Which is always considered as true.
The Configurator does not know anything about
"%kernel.debug%" being a parameter. -->
</container> |
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$container->loadFromExtension('my_bundle', array(
'logging' => true,
// true, as expected
)
);
$container->loadFromExtension('my_bundle', array(
'logging' => "%kernel.debug%",
// true/false (depends on 2nd parameter of AppKernel),
// as expected, because %kernel.debug% inside configuration
// gets evaluated before being passed to the extension
)
);
$container->loadFromExtension('my_bundle');
// passes the string "%kernel.debug%".
// Which is always considered as true.
// The Configurator does not know anything about
// "%kernel.debug%" being a parameter. |
为了支持这个用例（译注：让my_bundle: ~模式下不解析成字符串），Configuration 类必须通过以下的扩展来注入这个参数：
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namespace AppBundle\DependencyInjection;
use Symfony\Component\Config\Definition\Builder\TreeBuilder;
use Symfony\Component\Config\Definition\ConfigurationInterface;
class Configuration implements ConfigurationInterface
{
private $debug;
public function __construct($debug)
{
$this->debug = (bool) $debug;
}
public function getConfigTreeBuilder()
{
$treeBuilder = new TreeBuilder();
$rootNode = $treeBuilder->root('my_bundle');
$rootNode
->children()
// ...
->booleanNode('logging')->defaultValue($this->debug)->end()
// ...
->end()
;
return $treeBuilder;
}
} |
并且通过 Extension 类来把它设置到 Configuration 的构造器中：
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namespace AppBundle\DependencyInjection;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\DependencyInjection\Extension;
class AppExtension extends Extension
{
// ...
public function getConfiguration(array $config, ContainerBuilder $container)
{
return new Configuration($container->getParameter('kernel.debug'));
}
} |