Use condition in my views
Assuming you have a boolean field which stores if event is rejected or validated, you can read this information from PHP and print the fontawesome icon based on a condition.

The standard way in Drupal 7 would be to use Views PHP module and do something like:

if ($data-&gt;field_field_event_validated['0']['raw']['value'])
  echo '&lt;i class="fa fa-check"&gt;&lt;/i&gt;';
else
  echo '&lt;i class="fa fa-ban"&gt;&lt;/i&gt;';


This module still isn't ported to Drupal 8, and actually it's really bad in terms of security and stability to use this module as this article states. The same article describes how to include PHP in your views. In resume you have to create a module, generate a custom views field with the PHP code printing your icon and use this module in Views.