What's on this page

• Create the extension class
• Register the extension
• Use it in templates

Add a custom Twig function or filter

Cecil provides many template functions and filters, but you can add your own with a Twig extension written in PHP.

Create the extension class

Add a PHP file in the extensions directory of your site, with your own namespace (e.g.: MySite\Twig, the Cecil\ namespace being reserved), the file path matching the namespace:

extensions/MySite/Twig/MyTwigExtension.php

<?php
namespace MySite\Twig;

class MyTwigExtension extends \Twig\Extension\AbstractExtension
{
    public function getFilters(): array
    {
        return [
            // {{ 'text'|md5 }}
            new \Twig\TwigFilter('md5', 'md5'),
            // {{ page.content|word_count }}
            new \Twig\TwigFilter('word_count', [$this, 'wordCount']),
        ];
    }

    public function getFunctions(): array
    {
        return [
            // {{ year() }}
            new \Twig\TwigFunction('year', fn () => date('Y')),
        ];
    }

    public function wordCount(string $html): int
    {
        return str_word_count(strip_tags($html));
    }
}

Register the extension

Add the class name to the layouts.extensions map in cecil.yml, indexed by a name of your choice:

layouts:
  extensions:
    MyExtension: MySite\Twig\MyTwigExtension

Use it in templates

<p>{{ page.content|word_count }} words</p>
<footer>© {{ year() }} {{ site.title }}</footer>