Module Development

Concept: Altering Existing Forms for Drupal 8, 9, and 10

One of the most powerful features of Drupal's Form API is the ability to alter nearly any aspect of the build, validate, or submit workflow in your custom code. Implementing hook_form_alter is a common task for Drupal module developers, allowing them to modify forms to customize administrative or user-facing interfaces.

In this tutorial, we'll:

  • Explore the purpose and use case for hook_form_alter and related hooks.
  • Learn how to target specific forms.
  • Discover how to identify the form you wish to alter.

By the end of this tutorial, you should be able to select and implement the appropriate form alter hook to modify any form in Drupal.

Drupal Module Developer Guide