Using twig extensions in Drupal 7

Question

I would like to be able to use some custom PHP code that generates an SVG image in my .tpl.twig file. Since I can't write PHP in a twig template I figured I should try and make a twig extension (http://symfony.com/doc/current/cookbook/templating/twig_extension.html)

How could this be done in Drupal? Or is there another way?

Answer 1

When you are using tfd7 you can use extensions, functions, etc. The easiest way to go is to create an own module for handling all the php-functions.

In your OWN_MODULE.module:

function OWN_MODULE_twig_function() {
  $functions = [];
  $functions['XYZ_unset_key'] = new TwigSimpleFunction('XYZ_unset_key', 'XYZ_unset_key_callable');

  ...

  return $functions;
}

function XYZ_unset_key_callable($key, $array) {
  unset($array[$key];
  return $array;
}

After that you can use the function XYZ_unset_key in your twig-files:

<div>
  {{ XYZ_unset_key('field_xyz', 'content') }}
</div>