Symfony 3.4按文档配置运行时Twig扩展却无法加载，求排查

Alright, let's dig into why your lazy-loaded Twig extension isn't working in Symfony 3.4. I've gone through your code snippets, and there are a few key issues preventing the extension from loading correctly. Let's fix them step by step:

1. You Forgot to Register Your Twig Extension as a Service #

You created the AppExtension class, but Symfony doesn't know about it yet—you need to register it as a service with the twig.extension tag so Twig recognizes it.

Add this to your src/PlotlyBundle/Resources/config/services.yml:

services:
    # Keep your existing runtime service
    plotly.twig_runtime:
        class: PlotlyBundle\Twig\AppRuntime
        public: true
        tags:
            - { name: twig.runtime }
    
    # Add this new service for your extension
    plotly.twig_extension:
        class: PlotlyBundle\Twig\AppExtension
        public: true
        tags:
            - { name: twig.extension }

2. Incorrect Twig Function Definition for Lazy Runtime #

Your current getFunctions() method tries to call biDraw() as a static method, but lazy-loaded runtimes need explicit configuration to tell Twig to resolve the service instead.

Update your src/PlotlyBundle/Twig/AppExtension.php:

<?php
namespace PlotlyBundle\Twig;

use PlotlyBundle\Twig\AppRuntime;

class AppExtension extends \Twig_Extension
{
    public function getFunctions()
    {
        return [
            new \Twig_SimpleFunction(
                'bi_draw',
                [AppRuntime::class, 'biDraw'],
                ['runtime' => true] // This flag tells Twig to use the lazy runtime
            ),
        ];
    }

    // Optional but helpful for debugging: Give your extension a name
    public function getName()
    {
        return 'plotly_app_extension';
    }
}

The 'runtime' => true flag is critical here—it tells Twig to lazily load your AppRuntime service when the function is called.

3. Remove Unnecessary Runtime Fetch in Your Controller #

You don't need to manually fetch the runtime service in your controller—Twig handles that automatically when you call the function in your template. Delete this line from src/AppBundle/Controller/DashboardController.php:

// Remove this line, it's not needed
// $twig = $this->get('plotly.twig_runtime');

4. Clear Your Symfony Cache #

Old cached configurations can often cause issues like this. Clear the cache to make sure your new service definitions are picked up:

php bin/console cache:clear

After making these changes, your bi_draw() Twig function should render the 'awesome text here' output as expected.

内容的提问来源于stack exchange，提问作者numediaweb