Exercise: Preprocess Functions for Drupal 8, 9, and 10

Preprocess functions allow you change existing variables, or add new variables, for a template file using PHP code. In this final exercise for the course, you'll define a PHP function that implements a preprocess hook and define a new variable using PHP and make it available for use within a specific template file. Specifically we want to create a new variable named {{ today }} that contains the current date and gets passed to the page.html.twig template file. You should work on the exercise steps below first, and you can refer to the video if you need some help.

If you want to try and accomplish this on your own first you'll need to:

Learning objectives:

  • Create a THEMENAME.theme file.
  • Write a proprocess PHP function that adds variables to a page template file.

Note: At the end of this exercise, you'll find a video walk-through of the solution.