How to limit preprocess functions base on a theme?

Question

I'm working on a theme that using hook_preprocess_node and hook_preprocess_page and everything is working fine. However, whenever I go to any admin pages, it's throwing me some errors because the array changes. So what I'm trying to achieve is to add a condition only to run this preprocess function if using my theme.

How can I limit the preprocess function base on my theme?

Answer 1

You can check theme active with function:

<?php

$active = \Drupal::theme()->getActiveTheme()->getName();

Get list all themes with:

<?php

$themes = \Drupal::service('theme_handler')->listInfo()

Answer 2

If you implement the preprocess functions in your theme's template.php file, those will only be executed on the pages where the theme is applied.
So, if your admin theme is different (which is the case almost every time), the preprocess functions from your site theme would not be executed.