How to write a custom Twig Extension
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How to write a custom Twig Extension
The main motivation for writing an extension is to move often used code into a reusable class like adding support for internationalization. An extension can define tags, filters, tests, operators, global variables, functions, and node visitors.
Creating an extension also makes for a better separation of code that is executed at compilation time and code needed at runtime. As such, it makes your code faster.
Tip
Before writing your own extensions, have a look at the Twig official extension repository.
Create the Extension Class
To get your custom functionality you must first create a Twig Extension class. As an example you'll create a price filter to format a given number into price:
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// src/Acme/DemoBundle/Twig/AcmeExtension.php
namespace Acme\DemoBundle\Twig;
class AcmeExtension extends \Twig_Extension
{
public function getFilters()
{
return array(
'price' => new \Twig_Filter_Method($this, 'priceFilter'),
);
}
public function priceFilter($number, $decimals = 0, $decPoint = '.', $thousandsSep = ',')
{
$price = number_format($number, $decimals, $decPoint, $thousandsSep);
$price = '$' . $price;
return $price;
}
public function getName()
{
return 'acme_extension';
}
}Tip
Along with custom filters, you can also add custom `functions` and register `global variables`.
Register an Extension as a Service
Now you must let the Service Container know about your newly created Twig Extension:
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# src/Acme/DemoBundle/Resources/config/services.yml
services:
acme.twig.acme_extension:
class: Acme\DemoBundle\Twig\AcmeExtension
tags:
- { name: twig.extension }Note
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.
Using the custom Extension
Using your newly created Twig Extension is no different than any other:
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{# outputs $5,500.00 #}
{{ '5500'|price }}Passing other arguments to your filter:
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{# outputs $5500,2516 #}
{{ '5500.25155'|price(4, ',', '') }}Learning further
For a more in-depth look into Twig Extensions, please take a look at the Twig extensions documentation.
