Symfony - Unable to register extension “AppBundle\Twig\Extension\FileExtension” as it is already registered

问题

When I try to implement custom Twig Extension in Symfony2-project, I get following error:

Unable to register extension "AppBundle\Twig\Extension\FileExtension" as it is already registered.

In my app/config/services.yml, I have following:

parameters:
    app.file.twig.extension.class: AppBundle\Twig\Extension\FileExtension

services:
    app.twig.file_extension:
        class: '%app.file.twig.extension.class%'
        tags:
            - { name: 'twig.extension' }

In AppBundle/Twig/Extensions/FileExtension, i have:

<?php

namespace AppBundle\Twig\Extension;

class FileExtension extends \Twig_Extension
{
    /**
     * Return the functions registered as twig extensions
     * 
     * @return array
     */
    public function getFunctions()
    {
        return array(
            new \Twig_SimpleFunction('file_exists', array($this, 'file_exists')),
        );
    }

    public function getName()
    {
        return 'app_file';
    }
}
?>

I tried to clear cache, but not working. Anybody ideas why Twig renders twice?

回答1:

As @Cerad said, starting with Symfony 3.3, the twig extensions are automatically loaded and there is no need to define anything in the default services.yml.

Per the official documentation:

If you're using the default services.yml configuration, you're done! Symfony will automatically know about your new service and add the tag.

回答2:

In symfony 4, if you have autowire you can forget of configuring the services.yaml, your code would look the same in your services, only change the folder´s path.

namespace App\Util;

use Symfony\Component\HttpKernel\KernelInterface;
use Twig\Extension\AbstractExtension;
use Twig\TwigFunction;

class RemoteFileExtension extends AbstractExtension
{
    private $kernel;

    public function __construct(KernelInterface $kernel)
    {
        $this->kernel = $kernel;
    }

    public function getFunctions()
    {
        return array(
            new TwigFunction('remote_file', array($this, 'remoteFile')),
        );
    }

    public function remoteFile($url)
    {
        $contents = file_get_contents($url);
        $file = $this->kernel->getRootDir() . "/../templates/temp/" . sha1($contents) . '.html.twig';
        if (!is_file($file))
        {
            file_put_contents($file, $contents);
        }
        return '/temp/' . basename($file);
    }

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

回答3:

I had the same error in a Symfony 3.4 project.

It was a dependency injection of a custom TechnicianService into the twig extension that was causing this error in my case. After a lot of trial and error the solution was to move the specific function from the TechnicianService to a function into a TechnicianRepository and then inject the EntityManagerInterface into the twig extension, from which I could access my moved function again.

So in the beginning I had

class FindTechnicianByUrlExtension extends \Twig_Extension
{
    private $technicianService;

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

    public function getFunctions()
    {
        return [
            new \Twig_SimpleFunction('findTechnicianByUrl', function ($url) {
                return $this->technicianService->findTechnicianByUrl($url);
            })
        ];
    }
}

That had to change to this:

class FindTechnicianByUrlExtension extends \Twig_Extension
{
    private $em;

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

    public function getFunctions()
    {
        return [
            new \Twig_SimpleFunction('findTechnicianByUrl', function ($url) {
                return $this->em->getRepository(Technician::class)->findTechnicianByUrl($url);
            })
        ];
    }
}

It is a legacy project. Some older services are not autowired, maybe configured differently,... My new Twig extension uses autowire. Don't know what caused the problem but I did fix it. If somebody knows the exact cause by reading my solution, please let me know.

来源：https://stackoverflow.com/questions/46026221/symfony-unable-to-register-extension-appbundle-twig-extension-fileextension

标签

symfony

twig

twig-extension