Use HTTP_REFERER within a twig template

Question

I have a FAQ page with five nested bootstrap 5 accordions and I need to have one accordion item or another open depending on the page the user is coming from.

I tried using this:

{% set previousURL = app.request.headers.get('referer') %}

but I get nothing.

Using Drupal 9.

Answer 1

To do this you must either:

• Create a Twig extension for Drupal in a custom module. The extension type you should create is the function type.
• Implement hook_preprocess. See also, this short tutorial.