從Symfony2的樹枝擴展中使用幫助器服務

Question

我試圖設置一個樹枝過濾器這樣工作：{{entities | fieldnames}}將返回一個包含實體對象的屬性名稱的數組。 我的問題，閱讀並嘗試幾個小時後，我不能執行Twig Extension php中的$ this-> container-> get（「helpers」）。看起來我沒有正確地鏈接服務容器......請幫忙;）

錯誤：調用成員函數get（）在/ Users/a77/Dropbox/06中的非對象.Proyectos/2011的U Vox的/ DEV U形Vox的/ UVOX網絡/ SRC/Acme公司/ DemoBundle /擴展/ FieldnamesTwigExtension.php線38

或者，如果構建體而不= NULL 錯誤 ContextErrorException：捕致命錯誤：傳遞給Acme \ DemoBundle \ Extension \ FieldnamesTwigExtension :: __ construct（）的參數1必須是Acme \ DemoBundle \ Extension \ Container的一個實例，沒有給出，在

services.yml

services:

helpers: 
    class:  Acme\DemoBundle\Services\Helpers 

twig.extension.acme.demo: 
    class:  Acme\DemoBundle\Twig\Extension\DemoExtension 
    arguments: [twig.loader] 

acme.demo.listener: 
    class:  Acme\DemoBundle\EventListener\ControllerListener 
    arguments: [twig.extension.acme.demo] 

fieldnames: 
    class: Acme\DemoBundle\Extension\FieldnamesTwigExtension 
    arguments: [@service_container] 

擴展\ FieldnamesTwigExtension.php

use Symfony\Component\DependencyInjection\ContainerInterface as Container; 
namespace Acme\DemoBundle\Extension; 

class FieldnamesTwigExtension extends \Twig_Extension { 
private $container; 
public function __construct(Container $container=null) 
{ 
    $this->container = $container; 
    //var_dump ($container); exit; // prints null !!! 

} 
protected function get($service) 
{ 
    return $this->container->get($service); 
} 

public function getFilters() { 
    return array(
     'fieldnames' => new \Twig_Filter_Method($this, 'fieldnamesFilter'), 
    ); 
} 

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

public function fieldnamesFilter($obj) { 
    if (is_array($obj)) { 
     $first = $obj[0]; 

// GET (HELPERS) NOT WORKING : 

     $fieldnames = $this->container->get("helpers")->getFieldnames($first); 
     return $fieldnames; 
    } 
    return null; 
} 

public function twig_array_get_function($array, $name) { 
    return $array[$name]; 
} 

} 

Helpers.php

namespace Acme\DemoBundle\Services; 

class Helpers { 

public function sum($n1, $n2) { 
    return $n1 + $n2; 
} 

public function getFieldnames($entities) { 
    $reflect = new \ReflectionClass($entities[0]); 
    $props = $reflect->getProperties(); 
    $fieldnames = Array(); 
    foreach ($props as $prop) { 
     $fieldnames[] = $prop->getName(); 
    } 
    return $fieldnames; 
} 

} 

AcmeDemoExtension .PHP

namespace Acme\DemoBundle\DependencyInjection;

use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\HttpKernel\DependencyInjection\Extension; use Symfony\Component\Config\FileLocator; use Symfony\Component\DependencyInjection\Definition; // Added

class AcmeDemoExtension extends Extension {

public function load(array $configs, ContainerBuilder $container) { 

    $definition = new Definition('Acme\DemoBundle\Extension\AccessTwigExtension'); 
    $definition->addTag('twig.extension'); 
    $container->setDefinition('access_twig_extension', $definition); 

    $definition2 = new Definition('Acme\DemoBundle\Extension\FieldnamesTwigExtension'); 
    $definition2->addTag('twig.extension'); 
    $container->setDefinition('fieldnames_twig_extension', $definition2); 


    $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/../Resources/config')); 
    $loader->load('services.yml'); 
} 

public function getAlias() { 
    return 'acme_demo'; 
} 

} 

Answer 1

我在你的應用程序上試過你的代碼，並且有同樣的錯誤。要解決這個問題：

的Acme \ DemoBundle \ DependencyInjection \ AcmeDemoExtension.php

刪除此行：

$definition2 = new Definition('Acme\DemoBundle\Extension\FieldnamesTwigExtension'); 
$definition2->addTag('twig.extension'); 
$container->setDefinition('fieldnames_twig_extension', $definition2); 

的Acme \ DemoBundle \資源\ CONFIG \ services.yml

更換此行：

fieldnames: 
    class: Acme\DemoBundle\Extension\FieldnamesTwigExtension 
    arguments: [@service_container] 

通過：

fieldnames: 
    class: Acme\DemoBundle\Extension\FieldnamesTwigExtension 
    arguments: [@service_container] 
    tags: [{ name: twig.extension }] 

Answer 2

在你擴展\ FieldnamesTwigExtension.php，這是正常的，你的namespace是use指令後，叫什麼名字？

Symfony返回哪個錯誤？

Answer 3

你正在這樣太難。你應該直接將助手注射到你的樹枝裏。你也應該在services.yml中做你的標記。不在依賴注入擴展中。

http://symfony.com/doc/current/cookbook/templating/twig_extension.html

服務。yml

fieldnames: 
    class: Acme\DemoBundle\Extension\FieldnamesTwigExtension 
    arguments: [@helpers] 
    tags: 
     - { name: twig.extension } 

並相應地調整其餘代碼。