树枝扩展中的Symfony依赖注入 [英] Symfony dependency injection in twig extension

问题描述

好的，我试图创建依赖于其他服务（security.context）的树枝扩展，但遇到了一些麻烦。因此，这是我的服务声明：

Ok, I was trying to create twig extension with dependencies on other service (security.context) and got some troubles. So, here is my service declaration:

acme.twig.user_extension:
        class: Acme\BaseBundle\Twig\UserExtension
        arguments: ["@security.context"]
        tags:
            - { name: twig.extension }

这是我的课程

// acme/basebundle/twig/userextension.php

namespace Acme\BaseBundle\Twig;

use Symfony\Component\Security\Core\SecurityContext;
use Acme\UserBundle\Entity\User;

class UserExtension extends \Twig_Extension
{

    protected $context;

    public function __construct(SecurityContext $context){
        $this->context = $context;
    }

    public function getFunctions()
    {
        return array(
            'getAbcData' => new \Twig_SimpleFunction('getAbcData', $this->getAbcData()),
        );
    }

    public function getAbcData()
    {
        if ( !is_object($user = $this->context->getToken()->getUser()) || !$user instanceof User){ return null; }
        return array(
            'data_array'   => $user->getData(),
        );
    }

    public function getName()
    {
        return 'user_extension';
    }
}

最后，我有一个错误：

FatalErrorException: Error: Call to a member function getUser() on a non-object in \src\Acme\BaseBundle\Twig\UserExtension.php line 27

我想是 security.context 服务还没有初始化，然后我得到一个错误。
谁能告诉我，有什么方法可以手动加载服务，或者有更好的解决方案？
非常感谢。

I guess that security.context service is not initialized yet, then i get an error. Could anyone tell, please, is there are ways to load service manually, or any better solutions for an issue? Thanks a lot.

我使用Symfony 2.5。*

UPD：

我也在symfony文档中发现此通知

I've also found this notice in symfony docs

请记住，Twig Extensions不是延迟加载的。这意味着，如果有任何服务（或本例中的Twig扩展）依赖于请求服务，则您更有可能收到CircularReferenceException或ScopeWideningInjectionException。有关更多信息，请查看如何使用示波器。
实际上，我不知道如何纠正它。.

Keep in mind that Twig Extensions are not lazily loaded. This means that there's a higher chance that you'll get a CircularReferenceException or a ScopeWideningInjectionException if any services (or your Twig Extension in this case) are dependent on the request service. For more information take a look at How to Work with Scopes. Actually, I have no idea about how to do it correct..

推荐答案

您在构造Twig_SimpleFilter时正在调用 $ this-> getAbcData（）。但是您必须传递可调用作为参数。

You are calling $this->getAbcData() when constructing Twig_SimpleFilter. But you have to pass a callable as argument.

public function getFunctions() {
    return array (
        'getAbcData' => new \Twig_SimpleFunction( 'getAbcData', array( $this, 'getAbcData' ))
    );
}

狮子座也是对的。您应先检查 getToken（）是否返回对象，然后再尝试 getToken（）-> getUser（）。

Leo is also right. You should check first if getToken() is returning an object before trying getToken()->getUser().

您还可以将用户作为参数传递给树枝： {{getAbcData（app.user）}} 。这样，该功能将更通用，可用于任何用户，而不仅仅是当前登录的用户。

You can also pass the user to the function as a parameter in twig: {{ getAbcData(app.user) }}. This way the function is more generic and could be used for any user, not just the currently logged in one.

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