通过可迭代的类名获取服务 - 注入的标记服务 [英] Get service via class name from iterable - injected tagged services

问题描述

我正在努力通过类名从注入的标记服务组中获取特定服务.

I am struggling to get a specific service via class name from group of injected tagged services.

这是一个例子:我将所有实现 DriverInterface 的服务标记为 app.driver 并将其绑定到 $drivers 变量.

Here is an example: I tag all the services that implement DriverInterface as app.driver and bind it to the $drivers variable.

在其他一些服务中，我需要获取所有标记为 app.driver 的驱动程序，然后实例化并仅使用其中的几个.但是需要的驱动程序是动态的.

In some other service I need to get all those drivers that are tagged app.driver and instantiate and use only few of them. But what drivers will be needed is dynamic.

services.yml

services.yml

_defaults:
        autowire: true
        autoconfigure: true
        public: false
        bind:
            $drivers: [!tagged app.driver]

_instanceof:
        DriverInterface:
            tags: ['app.driver']

其他一些服务:

/**
 * @var iterable
 */
private $drivers;

/**
 * @param iterable $drivers
 */
public function __construct(iterable $drivers) 
{
    $this->drivers = $drivers;
}

public function getDriverByClassName(string $className): DriverInterface
{
    ????????
}

因此，实现 DriverInterface 的服务被注入到 $this->drivers 参数中作为可迭代结果.我只能通过它们foreach，但随后所有服务都将被实例化.

So services that implements DriverInterface are injected to $this->drivers param as iterable result. I can only foreach through them, but then all services will be instantiated.

是否有其他方法可以注入这些服务，通过类名从它们那里获取特定服务，而无需实例化其他服务?

Is there some other way to inject those services to get a specific service via class name from them without instantiating others?

我知道有可能将这些驱动程序公开并使用容器，但如果可以通过其他方式实现，我希望避免将容器注入服务.

I know there is a possibility to make those drivers public and use container instead, but I would like to avoid injecting container into services if it's possible to do it some other way.

推荐答案

A ServiceLocator 将允许按名称访问服务，而无需实例化其余服务.它确实需要编译器通过，但设置起来并不难.

A ServiceLocator will allow accessing a service by name without instantiating the rest of them. It does take a compiler pass but it's not too hard to setup.

use SymfonyComponentDependencyInjectionServiceLocator;
class DriverLocator extends ServiceLocator
{
    // Leave empty
}
# Some Service
public function __construct(DriverLocator $driverLocator) 
{
    $this->driverLocator = $driverLocator;
}

public function getDriverByClassName(string $className): DriverInterface
{
    return $this->driverLocator->get($fullyQualifiedClassName);
}

魔法来了:

# src/Kernel.php
# Make your kernel a compiler pass
use SymfonyComponentDependencyInjectionCompilerCompilerPassInterface;
class Kernel extends BaseKernel implements CompilerPassInterface {
...
# Dynamically add all drivers to the locator using a compiler pass
public function process(ContainerBuilder $container)
{
    $driverIds = [];
    foreach ($container->findTaggedServiceIds('app.driver') as $id => $tags) {
        $driverIds[$id] = new Reference($id);
    }
    $driverLocator = $container->getDefinition(DriverLocator::class);
    $driverLocator->setArguments([$driverIds]);
}

而且很快.假设您修复了我可能引入的任何语法错误或拼写错误，它应该可以工作.

And presto. It should work assuming you fix any syntax errors or typos I may have introduced.

为了获得额外的积分，您可以自动注册您的驱动程序类并删除服务文件中的那个 instanceof 条目.

And for extra credit, you can auto register your driver classes and get rid of that instanceof entry in your services file.

# Kernel.php
protected function build(ContainerBuilder $container)
{
    $container->registerForAutoconfiguration(DriverInterface::class)
        ->addTag('app.driver');
}

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